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Report of Chairman of Board of Accident Inquiry on accident which occurred on 30th November, 1961, near Sydney, New South Wales - Viscount VH-TVC operated by Australian National Airways Pty Ltd


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T H E PARLIAM ENT OF THE COMMONWEALTH OF AUSTRALIA.

AIR NAVIGATION REGULATIONS.

REPORT OF CHAIRMAN OF BOARD OF ACCIDENT INQUIRY

ACCIDENT WHICH OCCURRED ON 30th NOVEMBER, 1961, NEAR SYDNEY, NEW SOUTH WALES, TO VISCOUNT AIRCRAFT VH-TVC OPERATED BY AUSTRALIAN NATIONAL AIRWAYS PTY. LTD.

2 9 t h AUGUST, 1962.

Presented by Command, 3rd October, 1962; ordered to be printed, 1 lth October, 1962.

[C o n o f P a p e r :—Preparation, not given; 850 copies; approximate cost of printing and publishing, £140.]

Printed and Published for the G o v e r n m e n t o f t h e C o m m o n w e a l t h o f A u s t r a l i a by A . J. A r t h u r , Commonwealth Government Printer, Canberra.

( P r i n t e d i n A u s t r a l i a . )

N o . 1 3 7 [ G r o u p H ] , — F . 1 0 0 0 7 / 6 2 . — P r i c e I s . 6 d .

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R EPO R T OF C H A IR M A N O F BOARD OF A C C ID EN T IN Q U IR Y ON

A C C ID EN T W H IC H O C C U R R E D ON 30th NO VEM BER, 1961, N EA R SYDNEY, NEW SO UTH WALES, TO VISCOUN T A IR C R A FT VH-TVC, O PERA TED BY A U STR A LIA N N A TIO N A L AIRW AYS PTY. LTD.

CHAIRMAN: The Honourable Mr. Justice S p i c e r .

ASSESSORS: Captain C. A. H o w a r d , Mr. D. B. H u d s o n , Mr. H. A. W i l l s .

SECRETARY: Mr. J. O ’ C o n n o r .

M e l b o u r n e ,

29th A u g u s t , 1962.

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AIR NAVIGATION REGULATIONS.

BOARD OF ACCIDENT INQUIRY.

To: T he H onourable the M inister of State for C ivil A viation:

On the 7th day of March, 1962, pursuant to the Air Navigation Regulations, this Board of Accident Inquiry was appointed to inquire into an accident which occurred near Sydney in the State of New South Wales on 30th November, 1961, to Viscount Aircraft VH-TVC operated by Australian National Airways Pty. Ltd. The latter company operates regular public transport services as Ansett-A.N.A.

I was appointed Chairman of the Board, and Captain Colin Arthur Howard, Airline Transport Pilot, Douglas Beresford Hudson, Engineering Manager of Qantas Empire Airways Ltd., and Howard Arthur Wills, Deputy Controller, Trials and Instrumentation, Department of Supply, were appointed to the Board as Assessors.

At the date of the appointment of the Board investigations of the accident undertaken by the Department of Civil Aviation had not been completed and the inquiry did not commence until 12th June, 1962. Shortly before this date a long and detailed report of the investigations undertaken by the Department was made available and was distributed to parties known to be interested in the conduct of the inquiry and intending to be represented thereat.

The inquiry opened in Sydney on 12th June, 1962. At the commencement of the proceedings I granted leave to appear before the Board to the following persons:—

Mr. R. G. Reynolds, Q.C., with him Mr. J. E. H. Pilcher (instructed by the Commonwealth Crown Solicitor, Mr. Η. E. Renfree) to assist the Board of Accident Inquiry.

Mr. J. E. Starke, Q.C., with him Mr. P. A. Coldham (instructed by Mr. M. W. Buxton of the Commonwealth Crown Solicitor’s Civil Aviation Sub-Office (Melbourne)) for the Department of Civil Aviation.

Mr. G. H. Lush, Q.C., with him Mr. M. Ravech (instructed by Mr. T. H. Moss of Alexander Grant, Dixon and King) for Australian National Airways Pty. Ltd. Mr. A. D. Pearce for Mrs. Patricia Dorothy Lindsay (widow of Captain Lindsay) and Mrs. Mildred Costello (mother of First-Officer Costello) and the Australian Federation of Air

Pilots.

Mr. R. J. McConnell (instructed by Taylor and Scott) for the Civil Air Operations Officers Association of Australia. Mr. B. L. Murray, Q.C., with him Mr. S. E. K. Hulme (instructed by Blake and Riggall) for the Australian National Airlines Commission.

Mr. D. G. Milne (instructed by Clayton, Utz & Co.) for Amalgamated Wireless (Australasia) Limited. Mr. G. Samuels (instructed by John Wight & Co.) for Vickers-Armstrongs (Aircraft) Limited. Mr. G. C. Remington (Chairman, Rolls Royce of Australia Pty. Ltd.), Group Captain

F. C. Carey and Mr. J. F. Lumsden for Rolls Royce of Australia Pty. Limited.

Both Mr. Milne and Mr. Remington in seeking leave to appear indicated that it did not, at that stage, seem that their continuing attendances at the inquiry would be necessary and they applied for and were granted leave to withdraw, it being indicated in each case that any assistance which the Board might seek from their clients would be readily made available. In fact they took no further active part in the proceedings. On 13th June Mr. A. D. Pearce asked for and was granted leave to appear on behalf of

Mr. and Mrs. David Keldie, the next-of-kin of Aileen Margaret Keldie, a hostess engaged on the aircraft and also on behalf of the Airline Hostesses Association. On the same day Mr. L. T. McGowan applied for and was granted leave to appear for the Professional Radio Employees Institute of Australia. In the event it did not become necessary for him to take any active part in the proceedings.

Evidence was given in Sydney on 12th, 13th, 14th, 15th, 18th, 19th, 20th, 21st, 22nd, 25th, 26th, 27th, 28th and 29th days of June, 1962, and on 2nd, 3rd, 4th, 5th, 6th, 9th and 10th days of July. Upon completion of the evidence the Board adjourned until 23rd July and it heard addresses on that day and on 24th, 25th, 26th and 27th days of that month.

The Board on 11th June, 1962, inspected wreckage of the aircraft which was assembled in a hangar at Sydney airport, and also flew in a Viscount 700 series aircraft over the route presumed to have been followed by VH-TVC on the night of the accident.

The Board took evidence from 94 witnesses and some 109 exhibits were tendered in the course of the hearing.

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The Board was greatly assisted in conducting the inquiry by the report of investigations into the accident conducted by specialists and experts from the Department of Civil Aviation and Ansett-A.N.A. under the direction o f the Director of Air Safety Investigation, Mr. C. A. J. Lum. The investigation team was divided into four groups each headed by a chairman. The groups and chairmen were—

Witness .. .. Mr. F. E. Yeend, Senior Inspector of Air Safety.

Engineer .. .. Mr. J. V. Doubleday, Inspector of Air Safety.

Operations .. Mr. F. E. Yeend, Senior Inspector o f Air Safety.

Aviation Medical .. Dr. J. C. Lane, Director of Aviation Medicine.

The witness group was appointed as the operations group upon completion of its earlier work in collecting evidence from a great number of witnesses in relation to many aspects of the accident.

THE FLIGHT.

The story of the flight which ended in the loss of VH-TVC can be shortly told by recording the communications which passed between the aircraft and traffic control officers at the aerodrome from the time when the aircraft received its clearance.

Throughout this report, unless otherwise indicated, times given are in the terms of eastern standard time and based upon a 24-hour clock. Tracks referred to are in degrees magnetic.

The aircraft was engaged in a scheduled transport service from Sydney to Canberra.

At 1914.08 hours the Surface Movement Controller in the Tower conveyed the clearance to the aircraft and this was acknowledged by it with the words— “ Go ahead.”

The approved flight plan indicated that the pilot proposed to proceed from Sydney to Canberra via the 222 track to Marulan, the first reporting point.

At 1915.08 hours the Surface Movement Controller conveyed the following message to the aircraft:—· “ Tango Victor Charlie. Proceed to Canberra. Change of plan, via the 244 diversion ’til 37 DME thence direct Marulan. Cruise flight level 160. Read back.”

to which the aircraft replied— “ Tango Victor Charlie change of route. 244 to 37 DME thence direct Marulan cruise 160.”

This message was acknowledged by the Surface Movement Controller.

At 1915.39 the aircraft communicated to the Approach Controller— “ Tango Victor Charlie. Ready."

to which at 1915.43 the Approach Controller replied— “ Tango Victor Charlie, continue runway heading to 3,000 before turning left and to pass over the field at 5,000 or above. Read back. Clear for take-off.”

At 1915.55 the aircraft replied— “ Tango Victor Charlie, continue runway heading to 3,000. Turn left and pass over the field at 5,000.”

This was acknowledged by the Approach Controller at 1916.

At 1921.50 the Approach Controller sent the following message:— “ Tango Victor Charlie, report altitude.”

A reply was received at 1921.53— “ Tango Victor Charlie, we are at — er 6,000.”

Which the Approach Controller acknowledged at 1921.58.

At 1922.05 the Approach Controller communicated as follows:— “ Tango Victor Charlie, now if you haven’t passed over the field you can proceed via the 217 from Padstow. The 222 is available but I suggest the 217 due to the storm to the south of the field. Report setting course from Padstow 217.”

The reply from the aircraft was received at 1922.20— “ Tango Victor Charlie, thank you the 217.”

At 1925.10 the Approach Controller communicated as follows:— “ Tango Victor Charlie, have you set course yet?”

and at 1925.25— “ Tango Victor Charlie, this is Sydney tower.”

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No reply was received to either of these messages and the latter message was repeated at 1925.44 and 1926.05. Thereafter the following messages were transmitted without any reply being received:— 1926.35—

“ Tango Victor Charlie, Tango Victor Charlie, this is Sydney tower do you read.” 1926.46—

Tango Victor Charlie, Tango Victor Charlie, I’m not receiving. If you’re receiving me go ahead with two key clicks.”

1927.02—

“ Tango Victor Charlie, Tango Victor Charlie, I’m not receiving anything from you, continue on track via the 217 from Padstow to Canberra and attempt to contact Canberra tower or area control now on 118—correction 128 decimal 5.”

1929.26—

“ Tango Victor Charlie, Tango Victor Charlie, this is Sydney tower.”

There was no reply to any of these messages.

A plan showing the expected flight path of VH-TVC is attached (Appendix 1).

It seems to be reasonably clear on the evidence that between 1925 and 1926 hours the aircraft plunged into Botany Bay and became a total wreck. There were no survivors among any of the passengers or crew.

In the absence of any reply from repeated messages transmitted to the aircraft the Uncertainty Phase of the Search and Rescue (S.A.R.) Procedures was declared at 1926.29 hours and upgraded to an Alert Phase of S.A.R. at 1931.50 hours.

In the early stages it was not unnaturally thought possible that a radio failure had taken place on the aircraft.

After the aircraft failed to arrive at its destination of Canberra at its estimated time of arrival, the Distress Phase of S.A.R. was declared at 2010 hours and this resulted in the full scale search activities being brought into effect as it became apparent some mishap had occurred.

The absence of any reports from people in the densely populated area over which the aircraft had been operating when communication was lost led to the belief that it had crashed into the sea. In the early morning of 1st December a portion of the upholstery from a pilot’s seat was discovered floating in Botany Bay and it was identified as coming from a Viscount type aircraft. Within two hours thereafter the partly submerged starboard outer wing was found and a little later the main wreckage was located.

The location and condition of the wreckage when recovered was of considerable significance in aiding the investigators in their search for the cause of the disaster. The partly submerged starboard outer wing was found in Botany Bay about 1,500 feet north of Bonna Point. The main wreckage was located in 25 feet of water some 8,350 feet north of the point at which the starboard outer wing was found.

The starboard outer wing was more or less intact but the main wreckage, which included the starboard inner wing, was greatly disintegrated. The condition of the wreckage, together with the fact that the starboard outer wing was found at such a distance from the main wreckage, led to the conclusion that the starboard outer wing had not become detached from the aircraft when it struck the water, but had

separated in flight. The investigations were ultimately conducted upon the basis that the detachment of the starboard outer wing in flight was the immediate cause of the disaster.

CREW AND PASSENGERS.

The operating crew on the aircraft on its fatal flight were— Captain: Stanley Arthur L indsay, 185 Homebush-road, Strathfield. First Officer: Benjamin Alexander Gray Costello, 17 “ Manar ” , 42 Macleay-street, Potts Point.

Hostess: Elizabeth Caroline H ardy, Flat 10, 40a Birriga-road, Bellevue Hill. Hostess: Aileen Margaret K eldie, Flat 9, 89a Cowles-road, Mosman.

The passengers, all adults, were— Mr. Eric George Cole, 65 North-street, Casino, New South Wales. Mrs. Bernice Kathleen F ord, Boronia-drive, O’Connor, Australian Capital Territory. Mr. James Kevin G aylard, 86 Finniss-crescent, Narrabundah, Australian Capital Territory. Dr. Jeffrey Gould H arrington, 37 Rawson-street. Deakin, Australian Capital Territory.

Mr. Richard York K night, “ Hillingdon ” , via Goulburn, New South Wales. Mr. Henry Lingard, 27 Savige-street, Campbell, Australian Capital Territory. Mr. Alexander Douglas O’N eill, 10 Wylie-street, Narrabundah, Australian Capital Territory.

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Mr. Bruce Francis R egan, 123 Lowanna-street, Braddon, Australian Capital Territory.

Mr. David Denholm Shaw, Melrose Valley, Tuggeranong, Australian Capital Territory.

Mr. Albert Soukieh, 46 Waller-crescent, Campbell, Australian Capital Territory. Mr. John Andrew Sutherland, 110 Macarthur-avenue, O’Connor, Australian Capital Territory.

The remains of all fifteen persons on board the aircraft were recovered from the sea and post­ mortem examinations reveal that all died instantly as the result of impact forces.

THE AIRCRAFT AND ITS RECORD.

The aircraft VH-TVC was manufactured by Vickers-Armstrongs (Aircraft) Limited, England, in 1954. It was a low wing monoplane powered by four Rolls Royce Dart turbine engines each driving a Rotol four-blade constant speed propeller. The aircraft was originally produced by the manufacturer as a model 720 Viscount. It had since been modified to meet the requirements of Trans-Australia Airlines and by reason of these modifications was redesignated as model 720C. Its seating capacity was 48 first-class passengers.

The aircraft was owned by the Australian National Airlines Commission for the whole of its existence, that Commission operating transport services as Trans-Australia Airlines. It was introduced into regular public transport service in Australia on 22nd December, 1954. It was operated and maintained entirely by Trans-Australia Airlines until March, 1960, when it was made available to Ansett- A.N.A. under a cross charter agreement. Under the terms of this agreement Ansett-A.N.A. accepted responsibility for all scheduled maintenance inspections and rectification of defects. Trans-Australia Airlines retained responsibility for overhaul of the aircraft, its engines and other components. The radio equipment installed in the aircraft was maintained throughout its existence by Amalgamated Wireless (A/asia) Pty. Ltd.

At the time of the accident the aircraft had flown a total of 16,946 hours of which 9,797 hours had been flown since its last complete overhaul. There is no record of it having been involved in any previous accident. It was operating under Certificate of Registration No. 2094 which prescribed the registration marking VH-TVC and which was issued by the Department of Civil Aviation on 26th May, 1958. This

certificate was valid until change of ownership. The aircraft was operating under a Certificate of Airworthiness No. 2065 which was last renewed at Melbourne on 2nd December, 1960. This certificate remained valid until 1st December, 1961, subject to the aircraft continuing to be operated and maintained in accordance with the Air Navigation Regulations and Orders and the approved maintenance system.

Some minor deficiencies disclosed by the maintenance records were noted, but none of these have any bearing on the accident.

On 28th November, 1961, the aircraft had been specially inspected in view of the pending expiry of its Certificate of Airworthiness, and the necessity for a renewal of that certificate. As a result of that inspection the Department required rectification of four minor items, which were in fact rectified, and a renewal of the Certificate of Airworthiness would have been available for it on 2nd December, 1961.

CAPTAIN AND FIRST OFFICER.

The Captain, Stanley Arthur Lindsay, was 43 years of age. He commenced his flying career as a trainee pilot with Airflite Pty. Ltd. in 1939. He obtained an A licence in that year and then a B licence in 1940. He enlisted with the Royal Australian Air Force in 1941 and ceased flying with the R.A.A.F. in 1944, He obtained a civil commercial pilot licence in October, 1944, at which time he was employed by Australian National Airways Pty. Ltd. In August, 1947, he obtained his first-class airline transport pilot licence and was subsequently employed as a pilot by Qantas Empire Airways Ltd. and later by Butler Air Transport Ltd. He flew for a number of years for Butler Air Transport Ltd. as pilot in command of Douglas DC3 type aircraft on regular public transport service and in 1958 he commenced to fly in command of Viscount 747 type aircraft with the same company. On 13th June, 1960, he was transferred to the staff of Ansett-A.N.A. and after completion of the necessary training he commenced to fly in command of Viscount 720 type aircraft. Ten days prior to the accident he satisfactorily completed the flight training requirements to fly in command of Viscount 832 type aircraft, but action to obtain an endorsement of his licence to that effect had not been taken at the time of the accident. At the commencement of the flight Captain Lindsay’s total flying experience amounted to 16,016 hours of which 12,362 hours had been in command including 802 hours on Viscount 720 type aircraft and 1,946 hours on Viscount 747 type aircraft. He held first-class airline transport pilot licence No. 219 which was due for renewal on 28th February, 1962. His flight radio telephone operator licence No. 28 was valid until 31st August, 1962, and he held a first-class instrument rating for ADF, ILS and DME procedures.

An examination of his records and the evidence of other pilots indicates that he was a competent and careful commander, and there is no evidence to suggest that he failed in any respect to perform the duties required of him on the night in question. He was in good health, had spent a quiet day at home prior to the commencement of the flight, and his conduct and demeanour on the night in question all indicate that he was in normal health and spirits.

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The First Officer, Benjamin Alexander Gray Costello, was 27 years of age. Fie first obtained a student pilot licence in October, 1952. He underwent his initial flying training with the Royal Aero Club of New South Wales. Fie obtained a private pilot licence in August, 1953, and his commercial pilot licence in May, 1956. He then undertook agricultural and air-taxi flying until May, 1957, when he commenced employment with Australian National Airways Pty. Ltd. The following month he obtained his third-class airline transport pilot licence which became a second-class licence on 1st June, 1958. He flew in Douglas DC3 and Bristol 170 type aircraft until May, 1959. On completion of the necessary

ground and flying training his licence was endorsed to permit him to act as first officer on Viscount 832 type aircraft in that month. In June, I960, his licence was endorsed to permit him to act as first officer on Viscount 720 and 747 type aircraft. At the commencement of the final flight of VH-TVC his total

flying experience amounted to 4,145 hours including 609 hours on Viscount 720 type aircraft and 1,122 hours on Viscount aircraft of other types. Fie held second-class airline transport pilot licence No. 206 which was due for renewal on 31st May, 1962. Flis flight radio telephone operator licence was valid until 30th November, 1962. He held also a second-class instrument rating for ADF, ILS and DME

procedure. He was a fully qualified first officer, competent to discharge tire duties of first officer on Viscount 720 type aircraft. There is nothing to suggest that he was not in good health or that he did not properly perform all duties required of him on 30th November. He had spent the day quietly prior to his

departure from his home for the airport that afternoon.

PRECEDING FLIGHTS OF VH-TVC ON 30th NOVEMBER, 1961.

The aircraft had been engaged in two previous flights on the fatal day. Captain Robert Parker Smith was the pilot for a flight to Canberra from Sydney which commenced at 0815 hours. The weather was overcast and raining throughout that flight and the Captain carried out an instrument descent at Canberra. The Captain described the flight conditions as being slightly bumpy but not severe. The

aircraft arrived at Canberra at about 0900 hours and remained on the ground throughout the day until about 1700 hours when it returned to Sydney. Prior to the return the usual pre-flight inspection was carried out by the crew and everything was in order. The check flight plan for the return to Sydney designated an altitude of 15,000 feet but with a view to avoiding the cloud the Captain, in the course of the

flight, obtained a clearance for a higher altitude, namely 17,000 feet. The flight from Canberra was uneventful apart from the fact that in the descent from Marulan there was what the Captain described as “ moderate turbulence ” . It was a perfectly normal flight and no defects in the aircraft manifested themselves at any time. The Captain met First Officer Costello on his return and informed him that it

was overcast with a low ceiling at Canberra, but otherwise did not discuss the weather.

BRIEFING OF CAPTAIN LINDSAY.

Captain Lindsay came into the briefing office between 1815 and 1830 hours.

The domestic forecaster on duty that night was Leonard James Bowdler. Captain Lindsay obtained from him the flight and aerodrome forecasts which, inter alia, indicated turbulence of moderate to heavy intensity. The weather was described as rain with scattered thunderstorms clearing south of Holbrook. An alternate, Wagga, was required for both Canberra and Sydney, the Sydney weather

being described as rain and thunderstorms.

Mr. Bowdler had some conversation with Captain Lindsay as to the weather. He indicated to him that a line of storms had been reported by Brookvale Radar at 1700 hours approximately 40 miles to the west. They appeared to be moving to the east. He proceeded—

“ You will see by the forecast that I have got thunderstorms on the forecast. Now, at the same time the 0500Z map (i.e. 1500 hours) which I have just analysed shows a front over Richmond and the storms associated with that. It looks as if the weather is clearing out to the west. I am not too sure whether there is another front

along the ranges but the weather west of the ranges is definitely clearing. The weather at Sydney, as you can see yourself, with this storm approaching is not very good, and we require an alternate, and it will probably be required right through the evening. Canberra requires an alternate. Canberra has special weathers out, and also Sydney, and because of the thunderstorm activity we have had a SIGMET out all day. There have been varying reports of turbulence but the storms now seem to—we have only had one or two pilots come in since the storms have developed in this area and the reports have indicated it is quite turbulent.”

Having obtained the flight and aerodrome forecasts Captain Lindsay prepared a flight plan which, inter alia, indicated that he proposed to proceed from Sydney to Marulan via the 222 track. The flight plan was approved by Donald Ritchie, the Air Traffic Control Briefing Officer. At the time of the presentation of the flight plan some discussion took place between Captain Lindsay and Ritchie as to the

weather. Ritchie said among other things that it was a murky night and that bad weather was approaching from the west. He said that he suggested to Captain Lindsay that when he taxied he should request from the Tower the latest information as to the approaching weather.

It does appear that Captain Lindsay prior to his departure copied instructions and advice from the Tower as to the runway to be used, the wind and barometric reading conveyed to another aircraft, FNG, departing for Dubbo shortly ahead of him and indicated to the Tower that he had done so.

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LOAD STATEMENT.

The passenger load statement was prepared by Russell James Sharpe, a senior traffic officer employed by Ansett-A.N.A. who was the load controller at the relevant time. The statement indicates that the take-off weight was 51,976 lb. and the estimated landing weight was 50,096 lb. The permissible maximum take-off weight for the flight to Canberra was 59,380 lb. Therefore it is clear that the all-up weight of the aircraft was much less than its permissible maximum. The centre of gravity was within permissible limits, and the Captain certified by signing the load statement that it was in order.

PRE-FLIGHT INSPECTIONS AND CHECKS.

The evidence indicates that all the usual inspections of the aircraft, the checking of the fuel and other steps required before flight were performed and indicated that everything was satisfactory. In particular it appears that the First Officer properly performed the pre-flight external check of the aircraft, and it is presumed that the usual cockpit checks were carried out by the Captain and First Officer.

LOCATION AND CONDITION OF WRECKAGE.

It will be necessary at a later stage of this report to examine in greater detail incidents at the airport relevant to the despatch of VH-TVC. Their significance however can, I think, be better appreciated when the cause of the disaster is indicated, and to reach conclusions in relation thereto one must turn to other sources.

In search for enlightenment in this regard I proceed to examine in the first place what conclusions can properly be drawn from the location and condition of the wreckage.

A plan of the wreckage trail is attached to this report (Appendix 2) and also a diagram of the aircraft from which can be identified the significant parts of the aircraft which separated in flight (Appendix 3).

All the pieces indicated on the plan and diagram can be identified from the following key to wreckage distribution:— W1 .. .. Main wreckage.

W2 .. .. Starboard outer wing.

W3 . . . . Starboard outer flap.

W4 . . . . A.ccess cover-plate for high level drip tube, No. 4 fuel tank.

W5 . . . . Inboard portion of starboard elevator.

W6 . . .. Outboard portion of starboard tailplane.

W7 . . .. Outboard portion of starboard elevator.

W8 .. .. Inboard portion of starboard tailplane.

LI, L2 and L3 .. Pieces of fairing No. 4 engine nacelle to wing. L4 . . .. Bracket from No. 4 engine cowl.

L5 . . . . Piece of skin from No. 4 engine cowl.

L6 . . . . Piece of fairing No. 4 engine nacelle to wing.

L7 . . .. Chordal member to spar attachment bracket (aft of spar).

L8 . . . . Inner tube of fuel quantity probe No. 4 tank, cel! No. 1.

L9 . . .. Piece of fuel tank bay lining from No. 4 tank bay.

L10 and LI 1 . . Pieces of chordal diaphragm, starboard outer wing. L12 . . . . Piece of starboard outer wing skin.

LI 3 . . .. Piece of skin from starboard outer flap.

L14 . . . . Piece of starboard tailplane skin.

L15 . . .. Piece of de-icingfduct from root end of starboard tailplane.

L16 . . .. Piece of starboard elevator skin.

L17 . . .. Piece of channel from starboard inner to outer wing joint.

L18 . . .. Outboard portion of starboard elevator trim tab.

From the plan it will be seen that the main wreckage was found in Botany Bay some 8,350 feet north of the location in which the starboard outer wing (W2) was recovered. The other wreckage recovered in the sea near the shore included the starboard outer flap (W3) and portions of the starboard tailplane (W6) and elevator (W7).

Further pieces of wreckage discovered on or near the southern shore of Botany Bay include other pieces of the starboard outer wing (LI2), outer flap (L13) and tailplane (L14) as well as pieces related to No. 4 (the starboard outer) engine.

The extent of the disintegration of the main wreckage leads inevitably to the conclusion that it was caused by the terrific impact encountered when the aircraft struck the water.

The location of other wreckage and the fact that it sustained lighter damage indicates that it separated from the aircraft before impact with the water while the aircraft was still in flight.

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In the light of these discoveries the departmental investigators carried out experiments with a view to determining, if possible, the height at which the separation of the starboard outer wing and tailplane took place. It is unnecessary to examine in detail the nature of these experiments, ft will suffice to say that they were designed to determine in the first instance the terminal velocity of various

pieces of wreckage used for the purposes of the investigation.

The path taken by an object which separates from an aircraft is determined by wind drift and ballistic trajectory. In considering both these factors the significant property o f the object is its terminal velocity.

In the course of the most careful, imaginative and detailed experiments it became possible to estimate within reasonable limits the position from which each relevant piece o f wreckage probably fell. When the trails assigned to the objects were plotted they tended to converge towards a point of origin which could be estimated as lying within a range of altitude between 3,500 and 5,500 feet.

It is not unnatural that an experiment of this kind should be approached by the uninitiated with some scepticism, and members of the Board and counsel appearing before it were not at first immune from this reaction. In the end, however, the members of the Board were greatly impressed with the care which had been taken by checks and counterchecks to avoid a misleading result.

The conclusion reached was that the aircraft broke up in flight at an altitude which it is thought can be limited to the range of 3,500 to 5,500 feet and at a distance between 5,000 and 7,000 feet due south of the main wreckage. The limitation of the range of altitude is subject to certain assumptions arising from the averaging of the estimated winds from the ground to those altitudes.

It is unnecessary, as indeed it is impossible, to determine precisely at what height the break-up occurred. The importance of the experiments lies in the indication they provide that the break-up did not occur at the maximum height which the aircraft must be assumed to have reached in the course of its flight. At 1921.53 hours the height given from the aircraft was 6,000 feet. At 1922.20 hours, or

some 27 seconds later, it was still in flight and apparently not in difficulties. By that time in the process of normal flight its altitude would have been over 6,500 feet. It is not unreasonable to assume that it continued to climb for at least another minute or so and that it probably approached a height of 8,000 feet. None of the experiments undertaken in relation to the terminal velocity of pieces of wreckage suggest a break-up at such a height. Other factors to which reference will hereafter be made also support the view that the altitude at break-up was appreciably less than 7,000 to 8,000 feet.

I therefore am of the opinion that the break-up did occur at an appreciably lower altitude than the maximum which the aircraft attained in the course of its flight.

The experiments support two other conclusions which I accept, namely— (1) A flight path having a substantial northerly component at break-up is indicated. (2) The failure of the starboard wing and subsequent failure o f the starboard tailplane occurred within a very short interval of time and it appears that the aircraft travelled

less than 1,500 feet between wing and tailplane failure.

STRUCTURAL SOUNDNESS OF STARBOARD O U TER WING.

In view of the conclusion that the immediate cause of the accident was the detachment of the starboard outer wing in flight the first consideration which suggests itself is whether that wing was structurally sound.

The wing had been subjected to routine X-ray tests on 31st October and 1st November, 1961. when no abnormalities were found.

Examination of the wreckage in particular reference to the starboard outer wing, which was recovered from the water, disclosed that the main spar lower boom of the wing failed in tension at a point about six feet outboard of the spar joint (wing station 323).

A portion of the lower spar boom containing the tensile fracture and a secondary crack running outboard from it was removed from the wing and was examined by the Defence Standards Laboratories, Sydney. The examination disclosed that the material of the boom complied with the appropriate specification, that the fracture resulted from tensile overloading, and that there was no evidence of pre-existing defects which could have caused premature failure. The view of the experts was that fatigue of metal and stress corrosion could be eliminated as causes o f the failure and that the spar boom had been subjected to some load greater than that which it was designed to withstand. I accept these conclusions. A piece of the lower spar boom immediately inboard of the primary failure was not recovered but I am satisfied that its recovery and examination w ould not have affected these

conclusions.

CAPACITY TO WITHSTAND STRESS IN FL IG H T .

The elimination of structural defect of the wing as the cause of its separation from the aircraft leads naturally to the conclusion that the aircraft encountered some force in flight which was greater than it was designed to withstand.

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The manufacturers of the aircraft were required to comply with the minimum standards as to the strength of the structure described by the British Civil Airworthiness Regulations. Those regulations require aircraft to be designed to withstand gusts in accordance with a prescribed diagram v/hich is called a gust envelope. It is a diagrammatic representation of the speeds at which an aircraft as a whole shall be designed to withstand specified gusts. Fundamentally it deals (inter alia) with three particular speeds, namely—

(1) The speed at which an aircraft will stall on encountering an upward gust of 66 feet per second.

(2) The speed at which the aircraft is designed to meet an upward gust of 50 feet per second. (3) The design diving speed to meet an upward gust of 25 feet per second.

The gust speeds referred to are a measure of the vertical velocity of a disturbed air mass encountered by an aircraft in flight.

The regulations require as a safety factor that the strength of the structure shall be such that it is able to withstand loads of one and one-half greater than those indicated by the gust envelope.

The aircraft VH-TVC was constructed in accordance with these regulations as to airworthiness.

After the accident Vickers-Armstrongs (Aircraft) Limited were asked to prepare a gust envelope applicable to a Viscount 720 type aircraft with a weight of 51,990 lb., a centre of gravity at 0.1975 of the mean cord and flying at an altitude of 6,000 feet. These specifications correspond with the weight and centre of gravity of VH-TVC on the night of the disaster, and the altitude is that given by message from the aircraft at 1921.53 hours.

If it be assumed as seems reasonable that the aircraft was travelling at a speed of 165 knots, the gust envelope prepared by the aircraft company indicates that the maximum gust the wing would have withstood, with the aircraft loaded as indicated, would be of the order of 184 feet per second. At 180 knots according to the same calculation the wing would have withstood a maximum gust in the order

of 166 feet per second. These are gusts far in excess of anything that has ever been recorded and on the evidence they must be excluded as possibilities. By reference to the gust envelope it was demonstrated that at speeds below 260 knots it was not possible for the wing to fail due to gust loading alone. In these circumstances the aircraft would stall.

This examination of the capacity of the aircraft to withstand gusts at the speed at which it may reasonably be assumed to have been travelling confirms the view of the departmental experts that the wing did not become detached at the maximum height which the aircraft must be presumed to have attained.

Consideration of the capacity of the aircraft to withstand stress loaded as on this night indicates that at speeds below 260 knots the wing would not break on rapid application of the elevator. Further at 300 knots it requires a gust of at least 88 feet per second to break the wing and at 400 knots one of 54 feet per second. These combinations are such remote possibilities as to lead to the view that the wing failure was induced by something more than gust and speed alone. To assume its failure on that account when flying between 6,500 and 8,000 feet at a speed between 165 and 180 knots is incomprehensible.

These calculations point to the conclusion that when the aircraft was at its maximum altitude something happened to cause an upset as a result of which the control of the aircraft was momentarily lost. The view of experts who have given careful consideration to all the circumstances is that the loss of control led to a rapid involuntary descent and that the speed of the aircraft, the endeavours of the pilot to recover control, together with turbulence, imposed on the wing a load which it was not designed to bear. The natural endeavours which the pilot would make to recover control could impose manoeuvre loads on the aircraft which combined with gusts of moderate intensity would, at a speed in excess of

260 knots, result in failure of the wing. I accept this conclusion as the most probable cause of the catastrophe.

CAUSE OF UPSET.

It is not difficult to conceive of a number of happenings inside the aircraft itself which might lead to loss of control. There is, however, no circumstance disclosed which suggests such an occurrence. The possibilities include of course the error, distraction or sudden incapacity of the pilot. The record of the messages which passed between the traffic control officers and the aircraft support the view that nothing of this kind had occurred up to a time within three minutes of the accident. There is no evidence of any such mishap having occurred thereafter.

While in the absence of evidence such happenings must remain as possibilities they are in my view extremely unlikely explanations of the accident.

A further possibility is some malfunctioning of the aircraft or its instruments or its systems. The examination of the wreckage disclosed no features which would even arouse suspicion in this regard. There is no evidence of fire or explosion in flight. The destruction in the pilot’s cabin was so great as to render any effective check of the instruments impossible. It was, for example, impossible

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to determine whether any malfunctioning of the artificial horizon, air speed indicator or other instruments had contributed to the disaster. The most that can be said is that such happenings remain in the realm of possibilities which in the circumstances are unlikely in the extreme. The maintenance and operating record of the aircraft particularly immediately prior to the flight supports this view.

In the weather conditions which prevailed at and in the vicinity of the Sydney aerodrome on the evening of 30th November to which more detailed reference will be made hereafter, it is clear that turbulence, at times of an extreme character, was being experienced by aircraft entering and leaving the field. Thunderstorms and lightning were prevalent and at the time of the departure of VH-TVC the ceiling was approximately 800 feet. Shortly after take-off the aircraft was seen to enter cloud and does

not appear to have been seen again in the course of its flight. What were the actual conditions prevailing at 6,000 to 8,000 feet is not known. The presence of turbulence in some degree seems highly probable and its presence to a degree which would render control of the aircraft difficult, not impossible.* To this may be added the possibility of vivid lightning interfering with the vision of the pilot.

Upon the whole of the evidence which has been placed before us, I am of the opinion that weather conditions such as I have suggested constitute the most likely explanation of the initial departure of the aircraft from the flight path it was following a minute or two before the accident.

THE FINAL DESCENT.

To account for the descent of the aircraft into the sea the most reasonable explanation is that control of the aircraft was lost to a substantial degree when it was flying at an altitude of over 6,500 feet and that thereupon the aircraft descended rapidly at increasing speed. It is not difficult to imagine that in this desperate situation the pilot would endeavour by any means in his power to recover control. The wing would thus be subjected to severe strain induced not only by the speed but also by loads imposed

by the manoeuvre to regain control and by any turbulence it encountered. A degree of turbulence which might prove crucial in these circumstances is not improbable.

This sequence of events is not inconsistent with the estimated speed of the aircraft at the time of the impact with the water, the time sequence of the entire flight, the lateral displacement of the aircraft in the latter part of its flight and with the conclusion that the flight path of the aircraft at that time had a substantial northerly component.

An examination of Nos. 2, 3 and 4 engines indicated they were operating at the time of impact with propeller blade angles of 53 degrees. From this known circumstance it is possible to determine the minimum speed at which the aircraft was travelling. The expert opinion, which I accept, is that if the engines were operating at the lowest revolutions for flight, namely, 10,400 revolutions per minute, the speed of the aircraft at the time of impact would be not less than 300 knots. If they were rotating at

a higher speed, the maximum being 14,500 revolutions, the speed of the aircraft would correspondingly increase and could have been as high as 400 knots.

These considerations lead me to accept the conclusion reached by the Director of Air Safety Investigation that the failure of the starboard outer wing was probably induced by a combination of manoeuvre and gust loading when the speed of the aircraft was in excess of 260 knots.

WEATHER.

In view of the conclusion I have reached that weather conditions probably contributed to the disaster, questions arise as to whether the aircraft should have embarked upon its flight when it did, or whether it should have been permitted to do so.

In examining these questions regard must be had primarily to the actual weather conditions at the airport, and in its immediate vicinity, as they were known to the pilot and to the officers responsible for briefing the pilot and clearing the aircraft for departure. It is necessary also to consider what were the actual conditions, as far as they are now known, with a view to determining whether the information

available to the officers was such as to justify the clearance which the aircraft was given.

Reference has already been made to the briefing of Captain Lindsay by Leonard James Rowdier, weather officer at the airport employed by the Bureau of Meteorology. Bowdler had available to him a weather chart on which are plotted surface weather reports from various stations. 'The plotting is done every three hours. The chart available at 1830 hours when Captain Lindsay was briefed was based upon reports of weather as at 1500 hours. He also had upper air charts which are compiled twice a day

and kept up to date by reports of the result of balloon flights every six hours and also by reports from aircraft.

In addition there are aerological diagrams indicating the state of the atmosphere which are compiled at set stations at 0900 hours each day. Bowdler was also aware of the conditions prevailing at the airport as the result of his own observations and had seen plots of thunderstorms disclosed by R.A.A.F. Radar at Brookvale.

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On 30th November, 1961, a SIGMET, which originated at the Mascot Weather Office, was issued at 0633 hours and reads as follows:— “ Widespread thunderstorm activity extending over SY FIR next 15 hrs. Clearing westwards from a line Griffith/Walgett

FIR refers to the Flight Information Region.

This SIGMET was still current at the time of the accident.

In a statement of duties carried out by him on 30th November, 1961, which was subsequently prepared by Rowdier the following appears:— “ (1800-1945) Briefed 5 pilots SY-ML-SY-CB. Briefed on 1500 chart. At 1800 it was evident that thunderstorm was to west of SY and by 1830 thunder could be heard and was over the airfield.

(1815-1845) Brief pilot SY-DU. This pilot had just returned from west and reported a front 30 miles west from SY when he came in with thunderstorms and severe turbulence. Weather was clear to west behind frontal line.”

The pilot referred to was the pilot of VH-FNG to whom further reference is made hereafter.

A lot of evidence was given as to actual weather experienced in the vicinity of the airport between 1830 hours and 1930 hours. It is clear that in that period storms moved across the area from west to east which were accompanied in places by heavy rain and thunder and lightning. The actual rainfall at the airport was not as heavy as at other places in the vicinity. In fact only 12 points were recorded in the rain gauge at the Tower between 1800 and 2100 hours, but it would seem that this fell in a relatively short period of time probably shortly after 1900 hours. The registration at Mascot within 2 miles north­ east of the airport was 16 points between 1910 and 1920 hours, a fall at the rate of 96 points an hour. At Randwick further to the north-east and within 4 miles of the airport 14 points fell between 1923 and

1926 hours. This was at the rate of 280 points per hour. These registrations are of significance as indicating heavy rain, in or about the area in which VH-TVC was cleared to fly, at its departure time.

In the transcript of communications which passed from officers at the airport to one another and to aircraft in flight there are frequent references to turbulence, at time severe, particularly to the west and south of the airport. For example at 1833.14 hours aircraft FNF was advised to expect extreme turbulence from the outer marker into the threshold of the 07 runway. At 1839.18 hours aircraft FNC called Sydney Radar for assistance “ through this w eather” . At 1854.56 Radar advised the Tower that a proposed left turn after take-off for aircraft TVP would take him into a “ fairly heavy old concentration there

The pilot of FNG en route for Dubbo at 1913.31 hours referred to “ low stuff” concentrated in and around Botany Bay and to the north-east. This pilot who had come in from Dubbo earlier had described the severity of the weather in blunt terms and chose to depart below 1,000 feet in the immediate vicinity of the airport.

Just before 1900 hours the following friendly banter was exchanged between the Senior Approach Controller in the Tower and the Captain of FN G :— Senior Approach Controller: “ It’s not the night for you to be flying Hank.” FNG: “ Oh you can say that again.”

Senior Approach Controller: “ It looks a bit rough out there.” FN G : “ We just came in.” Senior Approach Controller: “ Did y o u ? ” FNG: “ We came in about twenty past six.” Senior Approach Controller: “ It’s rough all right.” FNG: “ You can say that again.”

The record indicates that this conversation was probably heard by the pilot of TVC. I do not suggest that any of these comments indicated concern about the flight. The fact that they were made however, is indicative of the existence of somewhat abnormal conditions.

At the time of departure of VH-TVC there was a flash of lightning and loud thunder which prompted a remark by someone in the Tower to the effect that it sounded as if an aircraft had blown up.

At 1918.48 Tower reported to aircraft TVL then approaching the airport that there was a heavy storm to the south but clearing in the Padstow area. The cloud over the field was “ around about 750 and clear in the Padstow area ” .

The weather officer on duty at the airport at 1920 hours, approximately three minutes after TVC had departed, recorded in a Special Aerodrome Weather Report “ Thunderstorms ” . He said in his evidence that his report meant that at that time “ there were thunderstorms substantially over the ’drome” . At 1950 he again recorded “ Thunderstorms” .

At 1925 aircraft TVL landed from Melbourne. The pilot said the weather around the airport “ was the worst that I have ever seen in my experience” .

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The picture conveyed by the foregoing is confirmed by evidence from civilians who testified as to their recollection of weather conditions in the Rockdale, Bexley, Brighton and Botany Bay areas and also in the Georges River area, to the south-west and south of the airport.

Such evidence must of course be approached with caution. Witnesses’ recollection of time can be faulty, and there is perhaps a tendency by some to associate the accident with the weather and exaggerate the severity of the conditions which they believe they observed. They confirm, however, the picture conveyed by evidence from other sources, namely, that a storm of some intensity accompanied by

thunder, lightning, somewhat unusual cloud formation, and in a number of places very heavy rain, passed over the area between 1900 and 1930 hours.

This general picture is substantiated by the evidence of John Neil McCrae, Superintendent of the Development Section of the Bureau of Meteorology who, after the accident, supervised an analysis of the weather prevailing in the Sydney area on 30th November, 1961. A study of all available pluviograph charts and rainfall registrations revealed that the area from Richmond east to the coast and south to

Port Hacking was affected by two major thunderstorms on the evening of 30th November, 1961. The storms moved in a direction from slightly north of west to slightly south of east at speeds of the order of 10 knots. The northern most of the two storms made its appearance at Richmond aerodrome and gave 33 points of rain between 1720 and 1750. The storm appears to have intensified and slowed down over

the Sydney area as the occluded front came under the influence of the warm moist air mass in the coastal region. It produced 81 points between 1800 and 1820 at Wahroonga of which 75 points fell between 1810 and 1820. This is at the rate of 438 points per hour. One hundred and twelve points fell between 1900 and 1940 at Manly Heights and 67 points between 1925 and 1945 at Vaucluse. The southern most of the

two storms made its appearance at Warragamba giving 99 points between 1553 and 1710. It also apparently intensified as it moved east to give 60 points between 1820 and 1831 and a further 36 between 1850 and 1910 at Penshurst, whilst Cronuila experienced 333 points in the period 1832 to 1935 and over the shorter period 1855 to 1905, 97 points v/ere recorded. This is at the rate of 582 points per hour. These thunderstorms were described by Mr. McCrae as two major thunderstorms and he said that it would

seem from the record at Penshurst that there were at least two major cells in the thunderstorm that moved across Botany Bay. He said that the rainfall at Cronuila was unusual for the Sydney area. He classed it as very heavy.

Mr. Starke on behalf of the Department of Civil Aviation contended that on the evidence I should find that at the time of the departure of VPI-TVC the storm had passed over the airport and over the area in which it would fly via the 244 diversion. He suggested that the centre of the storm had then moved over to the Kurnell area. I am of the opinion that at the time of the flight thunderstorm conditions

still prevailed over the area in which the aircraft was directed to fly. I think they were of such a character as to call for some consideration, at or about the time of departure, as to whether the aircraft should be permitted to fly along the route it was cleared to take prior to reaching Padstow.

THUNDERSTORMS AND THE HAZARDS THEY PRESENT.

The menace which thunderstorms may at times present to the operation of aircraft has received much consideration in the course of the inquiry. In approaching this subject it is of some importance to appreciate that thunderstorms are a phenomenon encountered by aircraft, that they seriously interfere at times with the comfort of passengers and crew but there have in fact been few accidents directly caused

by thunderstorm activity. One fatality which bears a somewhat striking resemblance to the accident with which the Board is concerned occurred in relation to a Vickers Viscount at Maryland, United States of America on 12th May, 1959. The Civil Aeronautics Board in that case found upon all the available evidence that an inflight disintegration of the aircraft was caused by aerodynamic loads imposed on the

aircraft, which exceeded its design strength, and which were generated by an excessive air speed combined with turbulence and manoeuvre loads. That Board concluded that there was a loss of control of the aircraft in extreme turbulence in an area of thunderstorms and after a steep involuntary descent during the subsequent recovery, loads beyond the designed strength of the aircraft occurred. The evidence

clearly showed the existence of large rapidly developing thunderstorms in the area of the accident and the Board concluded that extreme turbulence most probably existed in and around those thunderstorms.

Despite the frequent occurrences of thunderstorms in Australia, and the widespread extension of aircraft operations since the war, no accident to a commercial aircraft has been attributed to thunderstorms. Reports of turbulence encountered in thunderstorms sometimes of an extreme character are not infrequent, but the absence of accidents resulting therefrom indicates that pilots have been

successful in avoiding or in countering their worst effects.

Knowledge on the subject of thunderstorms has been greatly enhanced in recent years by the publication in 1949 in the United States of America of a report of the Department of Commerce under the title of “ The Thunderstorm ” . The report is based upon a project which was scientifically designed to examine the nature of thunderstorm activity and its effects, and it involved the deliberate penetration

of thunderstorms and the collating of information ascertained as a result of these activities. The Director of the project in his introduction refers to the fact that “ a great debt of gratitude is due to the pilots and crew members who almost daily subjected themselves to unusual flying risks in order to obtain the airplane data which formed the backbone of the studies ” .

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The project was undertaken, as appears in the introduction, because among other things “ the severe turbulence occurring inside most thunderstorms was counted as one of the worst hazards of flying” . It was said “ in the interests of safety . . . information was needed concerning the internal structure and behaviour of the thunderstorm The publication is one of considerable authority and its

conclusions must necessarily carry great weight.

The Director of Air Safety Investigation in the course of his report on this accident states in reference to “ The Thunderstorm ”, “ This publication contains the results of a most detailed study of phenomena associated with thunderstorms based upon facts established under scientifically controlled experiment and test ” . He also says “ the findings contained in ' The Thunderstorm ’ point to expectations not inconsistent with many of the related phenomena associated with the weather situation which existed in the Sydney area at times relevant to this investigation ” .

It is not necessary for the purpose of this inquiry to investigate in detail the physical characteristics of the life cycle of the thunderstorm. A brief summary of this cycle will suffice. At page 19 “ The Thunderstorm ” defines and describes three stages of a thunderstorm’s life cycle. The three stages are— (a) the cumulus stage characterized by up draughts throughout the cell;

(.b) the mature stage characterized by the presence of both up draughts and down draughts at least in the lower half of the cell; and (c) the dissipating or decaying stage characterized by weak down draughts prevailing throughout the cell. The development of the cycle to the mature stage is marked by the first precipitation from the storm

and the down draught thereby introduced gradually spreads throughout the cell. The point at which the strongest down draught occurs is closely associated with the heaviest rainfall.

At page 139 there appears a finding that “ the greatest turbulence in the thunderstorm is found to be associated with the highest water concentrations. This relationship was found to hold at all levels within the storm ” .

The very heavy rain experienced in some quarters, at least in the area within the vicinity of the Sydney airport on the night of the accident, indicates the presence of conditions in which considerable turbulence would be present.

At page 133 it is stated that “ from studies reported . . . it is now known that the thunderstorm consists of a group of cells in which are concentrated the gustiness, drafts, hail and other elements that make flight through the storm hazardous ” .

The report further points out that a thunderstorm pattern in many cases is more complex than the ideal case described in the report because thunderstorms are frequently multi-cellular; and at any one time these cells can be at different stages of development. This situation will prolong the life of a thunderstorm and the period during which both up draughts and down draughts are likely to be encountered. I do not propose to follow further these physical properties or to discuss the inter-relation of storms. Such a discussion would only confirm in detail the general observations which can be made.

The conditions in Sydney on the night in question indicate that the phenomena were somewhat complex in character, and that turbulence of a significant degree might be encountered in comparatively widely separated regions.

It is of some importance to understand in simple terms two characteristics of a thunderstorm as described in the publication, namely, “ drafts ” and “ gusts ” as these are the factors which affect the aircraft and subject it to varying degrees of turbulence. “ The drafts cause systematic changes in the altitude of the plane ” (page 133) or carry it upwards or downwards whereas gusts “ cause pitching, rolling and yawing, and accelerations of the plane without a systematic change in altitude ’’ (page 135).

It is not easy to define degrees of turbulence with precision. In the evidence before us the standard most commonly adopted had relation to the circumstances in which the pilot would require the use of seat belts. Light turbulence could be encountered without this necessity. In moderate turbulence passengers would be required to fasten their seat belts but hostesses could be permitted to attend to

duties in the aircraft. In severe turbulence hostesses would be required to be seated and fasten their seat belts as well. The difficulties of definition in this regard are referred to at page 135 of “ The Thunderstorm ” in these terms. “ Many meteorologists use the classification of light, moderate and heavy for turbulence without having a clear realization of what constitutes turbulence of various intensities. Most flight crews, too, use these subdivisions, but to them turbulence intensity has some subjective meaning in terms of the airplane response or the degree to which it hinders them in carrying out their duties within the airplane A more precise measure of heavy turbulence is suggested at page 135 of the report in these terms. “ Through comparison of pilot reports of turbulence intensity during the flights with the measurements of effective gust velocities and gust frequencies the planes encountered, it was found that if the largest gust in a group of several contiguous gusts exceeded about 14 ft./sec., and at the same time the gust frequency was greater than 6 per 3,000 ft. of traverse, the Project flight crews most frequently reported turbulence as ‘ heavy This would seem to indicate that in the case of a Viscount flying at 165 knots heavy turbulence on this basis would involve it in encountering a gust once every two seconds. In the circumstances existing within the vicinity of the airport on the night in question it is by no means difficult to imagine the aircraft encountering conditions of this character.

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I have already referred to the fact that despite the hazards which thunderstorms present few accidents have been attributed to turbulence experienced as a result of their presence. This suggests that dangers from thunderstorms should be seen in proper perspective. Aircraft operation like sea voyages and many other human activities necessarily involve the taking of risks, and it may be that all possibility of fatalities occurring will never be eliminated if we seek to take advantage of the facilities which modern aircraft provide. It seems to me, however, that the problem presented by the presence of

thunderstorms in the Sydney area on the night of 30th November, 1961, is of a special character. When an aircraft is at cruising altitude the pilot has much more room for manoeuvre than when flying in restricted air space allotted to him at an airport for take-off or landing. As far as VH-TVC was concerned it was given quite precise instructions as to the course it was to take on its departure from the airport. In such a set of circumstances it seems to me of the utmost importance that an aircraft should not be required to follow a precise path which may, when it is in relatively low altitudes, lead it into conditions in which extreme turbulence may be encountered. If it is impossible to say with reasonable certainty that such conditions will not be encountered along that path it seems to me that a clearance for that path is one which should not be given.

Reference is elsewhere made to the fact that steps have now been taken to require the fitment of weather radar to a very substantial proportion of the aircraft operating on major air routes in Australia. This development will undoubtedly provide added protection to aircraft from the dangers associated with thunderstorms. At page 139 of “ The Thunderstorm ” the following appears. “ Radar is, without question, one of the best instrument aids to thunderstorm flying currently available. Analysis of Project data indicated that the maximum turbulence and drafts are coincidental in space with regions of high water content, and consequently are within the area delineated by the radar echo. It was found that most

of the turbulence in the storms flown was confined to the area delineated by the radar echo presented on the 1 scope of the control radar on the ground This extract also indicates the significance to be attached to any proposal for the erection of radar facilities at the new Commonwealth Building in Sydney. If

information from that installation were readily made available at the airport in circumstances of thunderstorm activity it would enable the identification of regions of high water content and thus indicate the presence of turbulence within the vicinity of the airport.

THE CLEARANCE AND ITS RELATION TO WEATHER CONDITIONS.

It is perhaps necessary to emphasize that, for present purposes, we are not concerned with the general weather conditions which were likely to be encountered in the whole flight to Canberra, but with the weather conditions likely to be encountered after entering cloud at the airport and in the flight to Padstow.

When he prepared his flight plan the route designated by Captain Lindsay was the 222 track, the normal route to Canberra. This would have taken him across Botany Bay. At the time of departure this was changed to the 244 diversion. This avoids Botany Bay.

As hereafter appears the change was prescribed by the Air Traffic Controller, Barry William Neyle. At 1911.19 hours the co-ordinator in the Tower spoke to Neyle as follows:— “ Tango Victor Charlie to Canberra.”

Neyle replied:— “ Holy hell, Tango Victor Charlie—got nothing on him son. Call you back.”

At that stage Neyle did not have any flight information as to VH-TVC. He immediately obtained the departure strip for the aircraft from Flight Data Officer Albert Malcolm Bush and then at 1912.33 hours spoke to the co-ordinator as follows:— “ Yes Brian, I didn’t have this Tango Victor Charlie when I quizzed with Al. about that bloke coming in down

the 222.”

and to the aircraft as follows:— “ Tango Victor Charlie proceed to Canberra. Change of plan via the 244 diversion to 37 D M E thence direct to Marulan. Cruise Flight Level 160.”

It is quite clear that this route was chosen by Neyle for VH-TVC without regard by him to weather conditions. Neyle himself confirmed this, Its choice was prompted by the fact that the 222 diversion was not available because of inbound aircraft. Neyle had earlier received information that aircraft VH-TFF due for departure at about 1950 hours would probably request a departure on the 244 diversion

to 37 miles DME from Sydney. When faced with the dilemma presented by the proposed route for VH-TVC it was not unnatural that Neyle, having regard solely to the requirements of traffic separation, should choose the 244 diversion.

The choice of the 244 diversion for VH-TFF appears to have arisen in the course of a conversation between the Captain of that aircraft and Rodoni, the Senior Operations Officer, at approximately 1850 hours. It appears to have had relation to a storm south-west of the field in the approximate area of the 222 diversion and v/as designed to avoid that storm. It related to a departure some half an hour later

F. 10007/63.— 2

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than the time of departure of VH-TVC. In the conditions prevailing on that night it could have little relationship to the conditions which VH-TVC might encounter between 1915 and 1930 hours in the immediate vicinity of the airport.

It seems quite apparent on the evidence that as far as VH-TVC was concerned the change of route had nothing to do with weather conditions in that vicinity. It seems likely that but for the problem presented by the requirements of traffic separation the aircraft would have been cleared to follow the normal route which had been designated in the flight plan. At 1911.19 hours VH-TVC was ready to take-off on that route. In little more than one minute the route was changed by Neyle. As the message from Neyle to the co-ordinator indicates, it was associated with “ that bloke coming in down the 222 ” .

At 1915.43 hours the Senior Approach Controller, Frederick Alfred Charters, gave to the aircraft the immediate directions it was to follow in departing from the airport. It was to continue the runway heading to 3,000 feet before turning left and to pass over the field at 5,000 feet or above.

I think that the choice of the left turn rather than a right turn had little to do with weather considerations. There are indications in the recorded conversations between Radar and the Tower that choice of one turn rather than the other had at times during the evening been dictated by weather considerations which might affect the comfort of the take-off. For example at 1907.19 hours FNG was

advised “ the best way out of here at the present time is a right turn after take-off” . In relation to VH-TVC however Radar advised at 1914.15 hours:— “ I don’t think it matters much which way they turn now. The worst of this stuff is slowly moving east and it’s either side of the runway heading ” ,

This seems to indicate that in the view of the radar officer it was immaterial which turn was taken. The aircraft would on either turn encounter some of “ this stuff” .

The directions as to altitude in the final take-off direction were, I think, dictated solely by traffic separation considerations, and without regard to the weather conditions likely to be encountered at the altitudes indicated. Charters in replying to a question as to the purpose of the altitude requirements said—

“ It is a normal air traffic control instruction to separate aircraft. In this particular case there were two aircraft inbound from the south who were both high-flying aircraft, and it was necessary to get TVC above their levels before setting course.”

A comment at 1916 hours from the Approach Controller to the Radar Officer— “ That’ll clear him of everything ”,

to which the Radar Officer replied— “ Yes I’d say so,”

related, I think, to other aircraft. For reasons referred to elsewhere in this report the radar did not reflect weather conditions above the airport.

RESPONSIBILITIES AS TO WEATHER.

The responsibilities of the Senior Operations Officer in relation to weather developments are set out in Airways Operations Instructions Ops. 17-1 which provide (inter alia)— “ 1.1 — From the time a flight plan is submitted until the aircraft has landed, the SOO shall maintain a close surveillance over all meteorological information relevant to the flight. This includes aerodrome periodic

and special weather reports, TAFORS and amendments thereto, amendments to route forecasts, SIGMET reports and inflight reports from pilots. Study of this information shall be supplemented as frequently as is desirable by discussion with meteorological officers. 1.2 -— The SOO shall be responsible for advising the pilot of any weather developments in his OCA which indicate actual or expected conditions significantly different from those which he believes are already known to the pilot. Details of significant differences appear in AOI/MET.

1.3 — If weather developments are such as to require any change in the previously submitted flight plan, the SOO shall advise the pilot of the new operational requirements. These may require that the pilot: (ia) Proceed to a planned alternate aerodrome; or (b) Proceed to an aerodrome not previously planned as a destination or alternate (to terminate the

flight, or to refuel); or (c) Vary the route; or (d) Vary the operating level (due to icing, turbulence, adverse winds, or reduced barometric pressure raising the lowest safe altitude); or (e) Hold over a destination or alternate aerodrome, or en-route, pending weather improvement; or (f) Delay departure, pending weather improvement.” In Section 3 of the same publication the following appears:—

“ 3.1 — The SOO shall keep under review all information concerning the activation of danger and restricted airspaces, and other activities which could cause hazard to aircraft. 3.2 — He shall ensure that pilots are informed of such activities and, in the case of restrictions, shall instruct them to vary their routes or altitudes, if necessary.” Also in the Instructions R.A.C. 4-5 the following appears:—

“ 2-6-3. Hazardous conditions. When special circumstances exist which, in the opinion of the senior tower controller on duty, would make a landing or take-off hazardous, he shall close the

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aerodrome to landings, take-offs or all operations, as appropriate. An entry shall be made in the Aerodrome Control Journal detailing the circumstances of the closure. N o t e . — The decision to execute a landing or take-off under cross-wind conditions rests solely with the

pilot in command, therefore cross-wind shall not be considered as a hazardous condition requiring aerodrome action.”

The immediate problem with which the Board is concerned relates to weather conditions in the immediate vicinity of the airport. Whose responsibility was it to have regard to possible weather conditions which the aircraft might encounter before it set course? The Senior Approach Controller may close the aerodrome to landings, take-offs, or all operations where the circumstances are such as to

make a landing or take-off hazardous. This, I think, relates to hazards which make the actual landing or the take-off such that danger to the aircraft may be encountered. Fog, low ceiling, obstructions on the runway are obvious illustrations. Mr. F. A. Charters was the Senior Approach Controller on duty at the relevant time. Fie was experienced in this work having served for 15 years as an Air Traffic

Controller. When Mr. Charters was asked what phenomena he could close for, his immediate reply was low cloud and visibility. When he was asked whether these were the only factors he indicated others, namely, works in progress on the runway, a concentration of birds on a particular section. He referred to strong gusts with a line squall coming through the airport producing hazards in the immediate take-off

as another element. When asked if he would be worried about turbulence 6,000 feet up he said he would if he knew it were there.

Mr. Charters’ conception of his duties as disclosed by this evidence was, I think, proper and consistent with the information available to him. He was primarily concerned with landing and take-off. Any concern he may have had with hazards which the aircraft might encounter when it was airborne was necessarily limited by the information he possessed. He had the forecast for the Sydney airport covering

his period of duty, and also relied on his own observation of weather conditions. He had acted as Radar Controller for 3 hours prior to 1800 hours and was acquainted with such weather conditions as the Radar disclosed during that period. He also had such information as came to him from aircraft approaching and leaving the airport. He had no information of conditions immediately above the airport at 5,000 feet and it does not appear that he ever directed his mind deliberately to the question of what conditions might be encountered on the immediate flight path allotted to VH-TVC. In his view the weather

conditions were not such as to call for any such consideration.

It remains to consider the respective responsibilities of the pilot and the Senior Operations Officer. It is undoubtedly true that the pilot may, and doubtless will, refuse to take-off if he considers the conditions hazardous. In fact Captain Lindsay displayed no hesitation at any time in undertaking the flight as scheduled. Apart from the information conveyed to him when he was briefed, his only knowledge of the weather conditions in the immediate vicinity at the time of take-off was that which he may have

acquired by observation or from interception of communications with other aircraft. Save to that extent he had no precise knowledge of the conditions he might encounter at 5,000 feet and above on the flight path prescribed by the clearance. The instructions conveyed to him at the moment of take-off were not such as to be called in question by him, and he could reasonably assume that they would not lead him into danger. No blame attaches to him for accepting the clearance he was given, and there

are no reasons for doubting that he followed the instructions which were given to him.

It is clear that the Senior Operations Officer on duty, Mr. Rodoni, could have delayed the departure of the aircraft pending weather improvement. His responsibility extended (inter alia) to weather- developments in relation to the whole route. When one considers the Airways Operations Instructions applicable to him and compares them with those applicable in relation to the Senior Approach Controller, one becomes conscious of the possibility that there may be a gap in the respective realms of responsibility which at least is not expressly covered. The Senior Operations Officer is primarily concerned with the

overall weather pattern on the route—in this case Sydney-Canberra.

This in itself is a very responsible task involving the proper consideration of flight plans for many aircraft with varying routes and destinations. It might well interfere with the proper discharge of these duties if in addition he were in circumstances such as existed at the airport on 30th November, 1961, required to ask himself at the moment of take-off of each aircraft whether it should take-off at that

instant. This seems a task more appropriately to be performed in the Tower by some officer specially charged with that responsibility, and armed, as far as possible, with the weather information necessary to its proper performance.

I am left with an uneasy feeling that in the conditions which prevailed it was not the clear responsibility of any officer to deliberate on the question whether turbulence which might be encountered immediately after take-off by VH-TVC called for a different flight path or for some delay in the departure of that aircraft. It is not possible to say that the consideration of that question would in fact have led to

alteration or delay, but I would feel easier in my mind if it had been expressly faced and answered.

RADAR.

As there was much discussion during the hearing on radar—airborne radar, ground-weather radar and ground-aircraft surveillance radar, it is appropriate that some comment should be made on all aspects of radar.

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I do not propose to enter at all into the discussion of the fitment of airborne weather radar to Australian aircraft except to note that the Department of Civil Aviation was very actively considering this problem prior to 30th November, 1961, and after that date took prompt action to make this fitment mandatory in major types of commercial aircraft on the Australian register. The time given for the incorporation of this equipment, namely until 1st June, 1963, seems not unduly long having regard to the problems which the operators may face in purchasing and incorporating the equipment.

It should not be assumed that the presence of radar equipment in VH-TVC would necessarily have enabled the pilot to become aware of any significant turbulence in time to avoid it. There are limitations on the effectiveness of airborne radar in operating on a course such as the aircraft was cleared to follow immediately after take-off. The most that can be said is that radar would have provided the pilot with

some valuable information as to weather conditions in his immediate path which would not be apparent from visual observation.

The second type of radar which came under discussion was the radar fitted at the time in the Sydney Airport Tower. The Departmental experts stated this equipment was installed primarily for the purpose of assisting in the separation of aircraft during the critical approach and departure phases and its use as a weather surveillance aid was its secondary role.

Airways Operations Instruction R.A.C. 5-2 provides— “ 8.1 — The Radar controller is not normally required to keep a special watch solely for storm detection but when echoes observed during normal working indicate the presence of severe storms or the approach or a front, he shall report details to Approach Control for transmission to the Meteorological Section.

8.2 — Any aircraft likely to be affected shall be advised. Circumnavigational assistance to aircraft shall be given if necessary.”

The wave length on which this radar operates and its fundamental design, which gives it optimum efficiency in its primary role, automatically renders it significantly less efficient in its secondary role. It does, however, with special manipulation, give an indication of areas of heavy rain and can thus be used as an aid to pilots in avoiding these particular areas. There is much evidence to indicate that on the night in question it was used frequently for this purpose.

It is wrong, however, to assume that this equipment is a weather surveillance radar except in a limited degree. Its use in detecting storm centres in the air space above the airport and its vicinity is limited by factors to which reference is made later.

The third type of radar which calls for comment is the type of ground radar which is designed specifically for weather detection and surveillance.

Evidence was given that such a type of radar was to be installed in the Sydney area on top of the new Commonwealth Building when this building is completed, but it was also stated that this equipment would be under the control of the Commonwealth Meteorological Bureau and would be used as an aid to general weather forecasting.

The responsibilities for the provision of meteorological services to the Department of Civil Aviation are laid down in Regulation 98 (1.) and (2.) of the Air Navigation Regulations and the regulation in question states— “ (1.) The Director-General shall make arrangements with the Director of Meteorology for the provision

of meteorological information in such form and in such manner and at such places as the Director-General considers necessary to ensure the safe, economic and regular operation of aircraft and to give effect to the Convention. (2.) To the extent (if any) to which the Director of Meteorology is unable to furnish the meteorological information considered necessary by the Director-General for the purpose specified in the last preceding sub-regulation, the Director-General may make such other arrangements as are necessary for that purpose.”

This regulation makes it clear that the Director-General can either arrange with the Director of Meteorology for specific weather advice or can make any other arrangements necessary for the purpose.

One of the problems which has troubled the Board in this inquiry has been the absence of significant meteorological information relating to the air space over and in the immediate vicinity of the airport and the absence of any equipment capable of providing this information. The officer responsible finally for clearing the aircraft on the night of 30th November, 1961, the Senior Approach Controller, Mr. Charters, has stated in evidence the type of meteorological advice he receives and also has indicated the means by which he keeps this information up to date. The sources available to him have already been referred to. In relation to conditions in the immediate vicinity from time to time he must principally rely on visual observation. When we are considering thunderstorms at an altitude of 6,000 feet or above in that vicinity at a time when the cloud base is as low as 800 feet and horizontal visibility reduced to a few miles, visual observation alone is far from adequate. The aid which the Senior Approach Controller can obtain from the existing radar installed in the Tower is limited in three ways: firstly by its inherent design as mentioned above; secondly because it is used primarily for ensuring aircraft separation clearance; and thirdly because a large sector of the sky from about 30 degrees above the horizon is not “ seen ” or scanned by the radar. The “ blind s p o t” is three miles in diameter at 5,000 feet and increases proportionally at higher altitudes. It was the weather conditions in this very region which were of crucial importance in the flight of VH-TVC.

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The events on the night of 30th November, 1961, suggest that more precise up to the minute information as to weather conditions in the immediate vicinity is required when thunderstorms prevail there. If ground radar is to be used for this purpose the facility should be located at a point which will enable it to scan the air space over, and in the vicinity of the airport.

It would seem that the radar which it is proposed to erect on the new Commonwealth Building in Sydney may be capable of providing the necessary information. It would be necessary for suitable arrangements to be made whereby, in weather conditions involving possible hazards to aircraft in the vicinity of the airport, continuous observation of the moving weather pattern would be undertaken and

constant information in relation thereto made available to air traffic controllers and pilots.

As in this inquiry the Board has only been concerned with conditions at the Sydney airport I coniine my comments in this regard to that airport. It may be that similar considerations arise in relation to other airports.

WAS CLEARANCE PROPER?

In the light of all the evidence placed before the Board, I am, I think, called upon to express a view as to whether the clearance ultimately given to VH-TVC was, in all the circumstances, a sound operational judgment.

In approaching this question it is desirable, as far as is humanly possible, to leave out of account the fact that the accident occurred.

Of course, if there has been no accident there would have been no inquiry, and the weather which in fact prevailed on that night would not have been subjected to the attention it has received.

It must also be borne in mind that the causes I have assigned for the accident are in the main probabilities. The immediate cause is, I think, established as a fact, namely that the outer starboard wing separated in flight. The rest is conjecture based upon a careful consideration of all the known circumstances. If the conclusions I have reached indicate what in fact occurred, it is apparent that

turbulent v/eather conditions contributed in a marked degree to the disaster. It would be wrong, however, to conclude from the fact that the calamity occurred that the aircraft necessarily encountered turbulent conditions in the course of its flight. The most I can say is that such an encounter is the most probable initial factor. If this conclusion is sound it follows that such conditions existed in the air space above

the airport or the immediate vicinity thereof.

The assessment I have made of the actual weather conditions existing at the airport at the time of the departure of the aircraft were, in my view, such as to call for caution in despatching aircraft into areas where significant turbulence might be encountered. In the conditions which prevailed I think the take-off path prescribed for VH-TVC was not one in relation to which it could be said with any degree of certainty

that it would not encounter such conditions. It was, as I have said, dictated by the requirements of separation of aircraft in the immediate vicinity without any deliberate consideration of the conditions which the aircraft might encounter on the path chosen for it. It is not difficult to suggest other courses which might have been taken. Some delay in the departure would have soon solved the problem of

separation, and a departure course such as was chosen by the Captain of FN G on his flight to Dubbo may have proved a wiser choice. Even the temporary closing of the airport for departures seems in the circumstances not an extreme step.

I do not find it necessary to determine which (if any) of these courses should have been followed. Indeed I am scarcely in a position to make such a decision.

My criticism is that the path chosen for VH-TVC was not determined with sufficient cautious regard for the elements to which I have referred. In that sense the clearance given was not based upon a sound exercise of operational judgment.

In an earlier section of this report I have indicated the doubts I entertain as to whether it was the particular responsibility of any officer to make the kind of judgment which, in the circumstances, I feel was called for. Having regard to the knowledge they had and to their understanding of their respective responsibilities, I do not find that the granting of the clearance arose from any culpable fault on the part

of any air traffic controller.

Some factors in particular which contributed, I think, in some degree to the course followed on the night of the accident are worthy of comment. There is a natural and very healthy disinclination to interfere with the judgment of pilots in operational matters. Pilots must have the final choice as to whether an operation shall be undertaken. They, however, like air traffic controllers, are not free from

human weaknesses, and may at times require protection from error arising, perhaps, from lack of adequate information or sound judgment. A disinclination to interfere should not inhibit appropriate action to deter.

The dangers associated with thunderstorm activity are referred to in another section of this report. Knowledge of these dangers has been enhanced by the publication “ The Thunderstorm ” to which reference has already been made. I cannot but feel that air traffic control officers at the airport were not as conscious of the hazards presented by thunderstorms as a perusal of that publication would have made them.

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TRANSCRIPT OF A IR TRAFFIC CONTROL TAPE RECORDINGS.

It will be apparent that in reaching conclusions as to the conduct of air traffic control officers at the airport on the night of the accident I have relied in the main upon the record of contemporaneous communications which passed between air traffic control officers themselves and between them and aircraft approaching or leaving the airport. This has proved to be a most valuable source of reliable evidence of what in fact transpired at the airport on the night in question, and a most useful corrective to the necessarily somewhat less precise details of events which the officers were able to recollect after the expiration of some six months.

All members of the Board had some misgivings in the course of the inquiry that the full text of the transcript of these communications was not made available to the Board and to counsel assisting the Board at the commencement of the inquiry and before the relevant Departmental officers were examined.

Indeed we feel that in the circumstances of this fatality the whole of the transcript might well have been revealed in the report of the Director of Air Safety Investigation. It seems to us that these records did not receive the same meticulous examination by Departmental investigators as was applied to other aspects of the accident.

SUMMARY OF CONCLUSIONS.

I summarize my conclusions as to the accident and the cause of the accident as follows:— (1) On 30th November, 1961, at approximately 1926 hours, Vickers Viscount 720C type aircraft VH-TVC owned by the Commonwealth of Australia, Australian National Airlines Commission, and operated by Ansett-A.N.A., crashed into Botany Bay at a distance of 2.8 nautical miles on a magnetic bearing of 140 degrees from Sydney Airport, New South Wales.

(2) The aircraft was a total wreck.

(3) The aircraft carried a crew of 4 and 11 passengers, all of whom were lost as a result of the fatality. (4) At the time of the accident the aircraft was engaged on a regular public transport service from Sydney to Canberra and had taken off from Runway 07 at the Sydney Airport at 1917 hours.

(5) The aircraft was under the command of Captain Stanley Arthur Lindsay, with First Officer Benjamin Alexander Gray Costello, and Hostesses Elizabeth Caroline Hardy and Aileen Margaret Keldie as crew members.

(6) The aircraft was operating under current Certificates of Airworthiness and Registration and was loaded within permissible limits. (7) The pilot and first officer were properly licensed, trained and competent officers. (8) They were both in good health and the evidence indicates that when the flight commenced they were fully capable of performing their functions in relation thereto.

(9) All airways and airport facilities pertinent to the flight were functioning correctly. (10) The aircraft was properly serviced and maintained and in a fit and proper condition for the flight. (11) All the evidence indicates that the aircraft followed the flight path designated for it.

(12) There is no evidence of any material, structural or systems defects having existed in the aircraft or its engines prior to the accident, and any damage or abnormalities in evidence during the examination of wreckage can be attributed either to inflight break-up or impact with the ground or water. (13) There is no evidence of fire, explosion or lightning strike which impaired the structural integrity or the safe operation of the aircraft.

(14) There is no evidence of sudden incapacitation of any member of the crew or any act by a person on board such as might affect the safety of the aircraft. (15) The starboard outer wing failed in flight in upward bending due to tensile overloading of the lower spar boom.

(16) The starboard tailplane failed due to compressive overloading of the upper spar boom consequent upon the failure of the starboard outer wing. (17) The failure of the starboard outer wing was not due to any structural defect or to stress corrosion or metal fatigue.

(18) The inflight failure of the starboard outer wing probably occurred when the aircraft was at a height substantially less than the maximum altitude reached in the course of the flight. (19) The aircraft in the course of its flight reached an altitude of not less than 6,000 feet and probably climbed to a height of between 6,500 and 8,000 feet.

(20) At the maximum height reached some set of circumstances was probably encountered as a result of which control of the aircraft was lost after which it rapidly descended at increasing speed. (21) The evidence does not suggest that such loss of control was caused or contributed to in any way by the action of the pilot or anyone on board the aircraft.

(22) The loss of control was most probably due to weather conditions in which the aircraft encountered extreme turbulence.

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(23) The possibility of the pilots’ vision being impaired by lightning cannot be excluded as a contributing factor.

(24) There is no evidence of any error committed by the pilot but the possibility of such an error has not been entirely excluded.

(25) There is no evidence to suggest that the instruments in the pilots’ cabin were not functioning normally and accurately. The evidence does not, however, entirely eliminate these elements as possible contributing factors.

(26) At the time of the failure of the starboard outer wing the aircraft was travelling at a speed in excess of 260 knots and at an appreciably higher speed when it struck the water.

(27) It is probable that action by the pilot to recover control of the aircraft during its rapid descent imposed a manoeuvre load on the aircraft which together with its speed and turbulence encountered, produced forces in the aircraft structure greater than it was designed to bear and which failed the starboard outer wing.

RECOMMENDATIONS.

(1) The functions of the Approach Controller in relation to hazardous conditions likely to be encountered by an aircraft in the vicinity of the Sydney airport require, I think, more precise definition. In particular when thunderstorm activity is present at or in the vicinity of the airport he should be responsible for determining whether a departure path designated for an aircraft is not such as to lead the aircraft into regions where severe turbulence may be encountered.

(2) When thunderstorm activity is present, he should be provided with the best current weather information pertinent to the assessment of the changing weather pattern. (3) Ground weather radar will greatly facilitate the provision of pertinent data. Such a facility should be capable of effectively scanning the region above the airport and its vicinity. With this in view

it is recommended that any such facility used should be situated at such a distance from the airport as will ensure its effectiveness in relation to that region. In conditions of thunderstorm activity constant contact between such radar and the Tower should be maintained. (4) These recommendations may, of course, have relevance to other airports.

ACKNOWLEDGMENTS.

Reference has already been made to the very excellent report on the accident prepared by and under the supervision of Mr. C. A. J. Lum, the Director of Air Safety Investigation. Each of the groups formed to conduct the investigation faced many difficulties involving long and arduous labours and calling for patience and imagination in the solution of difficult problems. The result they achieved is itself

eloquent testimony of the thoroughness of the task they performed. The Board is grateful to all of them for the assistance all its members derived from the report and the evidence which certain members of the investigating groups gave.

They and we were aided in certain aspects of the investigation by valuable material and evidence provided by representatives of Vickers-Armstrongs (Aircraft) Limited who were made available in Australia to assist in the investigation. Their contribution is deserving of the highest praise.

The Board also desires to record its acknowledgment of the invaluable assistance it received from all counsel who appeared before it.

It is appropriate also that the valuable work done by units of the Royal Australian Navy and by the New South Wales Police Force in the recovery of wreckage should be recorded.

The Secretary of the Board, Mr. J. O’Connor, has at all times performed the duties required of him with efficiency and expedition and the gratitude of all of us is recorded for the aid he has given us both during the hearing and|in the preparation of this report.

I wish to add my own personal thanks to the Assessors who have rendered most valuable assistance to me on many difficult technical aspects of the inquiry and have greatly aided me in the preparation of this report.

Dated this twenty-ninth day of August, 1962.

(Sgnd.) J. A. SPICER,

We agree with the findings and recommendations of the Chairman.

(Sgnd) C. A. HOWARD, Assessor.

(Sgnd.) D. B. HUDSON, Assessor.

(Sgnd.) H. A. WILLS, Assessor.

Chairman.

Printed and Published for the G o v e r n m e n t o f t h e C o m m o n w e a l t h o f A u s t r a l i a by A. J. A r t h u r , Commonwealth Government Printer, Canberra.

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APPENDIX 2

B A T E B A Y

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APPENDIX 3