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MINISTRY OF AVIATION


CIVIL AIRCRAFT ACCIDENT


Report on the Accident to
Vickers Viscount 793 TC-SEV at London (Gatwick) Airport on 17th February, 1959


Sister aircraft TC-SEL pictured

 

Accident Report No.C/694

ACCIDENTS INVESTIGATION BRANCH


Photo courtesy of and copyright S. Prior 2011

Photo courtesy of and copyright S. Prior 2011

AIRCRAFT Vickers Viscount 793
TC-SEV
 
     
ENGINES Four Rolls Royce Dart 510  
     
REGISTERED OWNER & OPERATOR Turk Hava Yollari (Turkish Airlines Incorporated)  
     
CREW Captain M. Ozbek - (In Command) - Killed  
  Captain L. Biberoglu - (Second Pilot) - Killed  
  Captain S. Kazmaoglu - (Reserve Pilot) - Killed  
  Captain G. Tezel - (Navigator) - Killed  
  Mr. T. Erkay - (Steward) - Seriously injured  
  Miss G. Uygur - (Stewardess) - Killed  
  Miss N. Yelkovan - (Stewardess) - Seriously injured  
  Mr. A. K. Itik - (Supernumerary Mechanic) - Uninjured  
     
PASSENGERS 16 ...... 9 killed, 7 injured  
     
PLACE OF ACCIDENT Jordan's Wood, Rusper, Sussex, England  
     
DATE AND TIME On 17th February, 1959, at about 1647 hrs.  
  All times in this report are GMT  

 

 

1. NOTIFICATION
By telephone from Air Traffic Control at 1710 hrs. on 17th February, 1959. The investigation commenced the same evening. A Turkish Technical Delegation was afforded full facilities to participate in the investigation.

2. BRIEF CIRCUMSTANCES
The aircraft was on a special flight from Ankara to London via Rome with M. Menderes the Prime Minister of Turkey and a party of Turkish Government officials on board. Shortly before it arrived in the holding pattern for London Airport, London Airways passed a message directing it to proceed to Gatwick Airport. Gatwick A.T.C. then took over the control of the aircraft and radar positioned it for final approach on the Instrument Landing System (ILS). During its approach to land the aircraft crashed in a wood obscured by fog 3 miles from the threshold of the runway.

3. FURTHER DETAILS

(a) The Aircraft
The aircraft was built by Vickers-Armstrongs (Aircraft) Ltd. and completed in 1958. A United Kingdom Certificate of Airworthiness was issued on 25th July, 1958 valid for one year and a Certificate of Validation for the same period was issued by the Civil Aviation Department of the Turkish Ministry of Communications. ' The aircraft was registered in the name of Turkish Airlines Incorporated.
The airframe had flown a total of 548 hours and the engines had each run approximately 615 hours since manufacture. The Turkish authorities after examining the appropriate records and log books in Turkey, certified that the maintenance had been properly carried out. Translated extracts from these documents have been examined. There is no record of any defect which might have had a bearing on the accident; it was noted that no inspections of the ILS equipment in the aircraft had been carried out.
At the time of the accident the weight of the aircraft was below the permissible maximum for landing. It was not possible to check the trim but there was no reason to suppose that it was not within the prescribed limits.

(b) The Crew

(i) The Captain
Captain M. Ozbek was 38 years of age. He had graduated as a pilot at the War School in Turkey in 1941 and then received further training in England. He served as an officer in the Turkish Air Force from 1943 to 1956 and then became Chief Pilot of Turkish Airlines Incorporated. At the time of the accident he held a valid Airline Transport Pilot's Licence and had completed a total of 7,716 flying hours of which 216 were on Viscount aircraft. During the 3 months prior to the accident he had completed 44 hours flying.
Captain Ozbek had had no instrument flying practice on the Link Trainer or Flight Simulator during the 6 months prior to the accident. He had completed 2 ILS approaches (without the use of the glide path) and 1 Ground Controlled Approach (GCA) and landing during the same period. Except for those carried out during conversion to Viscount aircraft in February, 1958, there is no record of any other flights involving the use of ILS or GCA. After his last flight check with Turkish Airlines he was assessed as "Above Average".
Captain Ozbek was flying the aircraft from the left-hand seat during the approach to Gatwick.

(ii) The Second Pilot
Captain Biberoglu was 35 years of age. He had graduated at the War School in Turkey in 1942 and then received further instruction in England during the period 1943-1945. He served as an officer in the Turkish Air Force from 1945-1950 and then joined Turkish Airlines. At the time of the accident he held a valid Airline Transport Pilot's Licence. His flying time amounted to 5,504 hours of which 103 were on Viscount aircraft. During the 6 months prior to the accident he had completed 2 GCA - but no ILS approaches. In the same period he had completed 24 ILS and 22 GCA practices in the Flight Simulator and Link Trainer. After his last flight check with Turkish Airlines he was assessed as "Good".
During the approach to Gatwick Captain Biberoglu was in the right-hand seat and was operating the radio telephone.

(iii) The Reserve Pilot
Captain S. Kazmaoglu was 35 years of age. He was a Company check pilot and held a valid Airline Transport Pilot's Licence. He had completed a total of 5,297 flying hours 198 of which were on Viscount aircraft. He had not flown Viscounts during the 3 months prior to the accident. During the 6 months prior to the accident he had completed 3 GCA approaches and had carried out 24 ILS and 22 GCA practices on the Flight Simulator and Link Trainer.
During the approach to Gatwick Captain Kazmaoglu was in the seat immediately behind the first and second pilots.

(iv) The Navigator
Captain G. Tezel was 42 years of age and held a valid Airline Transport Pilot's Licence. He had no experience as a Viscount pilot.

(c) Meteorological Data
A large anti-cyclone was centred over south-east England and the Low Countries on 17th February, 1959. The wind was calm or light southwesterly. Lifted fog or low stratus covered the higher ground restricting visibility in places to 100-200 yards. Over low ground the visibility was mainly 1,500 to 2,000 yards rapidly decreasing after 1700 hrs. with the formation of extensive fog to 100-200 yards.

Actual weather conditions observed at Gatwick Airport were:-
(All heights are above airfield level)

1628 hrs Surface wind calm.
  Visibility 1.1 nm, mist.
  Cloud 1/8 stratus, base 800 feet.
  QFE 1035.8 mb. QNH 1043.0 mb.
1657 hrs Surface wind calm.
  Visibility 1.0 nm., mist.
  Cloud 1/8 stratus, base 800 feet.
  QFE 1035.7 mb. QNH 1043.0 mb.
1706 hrs Surface wind calm.
  Visibility 1,800 yards, mist.
  No low cloud.
  Shallow ground fog patches (these patches were only 1 to 5 feet in depth).

The following observations of the weather at London Airport were available to the pilots on the VHP Meteorological weather broadcasts (VOLMET)

1455 hrs Surface wind 280° /01 knot.
  Visibility 330 yards.
  Sky obscured
  QNH 1044 mb.
  Runway Visual Range 300 yards.
1530 hrs. Surface wind 260°/01 knot.
  Visibility 330 yards.
  Sky obscured.
  QNH 1043.5 mb.
  Runway Visual Range 400 yards.
1555 hrs. Surface wind 240°/01 knot.
  Visibility 440 yards.
  Sky obscured.
  QNH 1043.4 mb.
  Runway Visual Range 450 yards.
1630 hrs. Surface wind 230°/01 knot.
  Visibility 440 yards.
  Sky obscured.
  QNH 1043.3 mb.
  Runway Visual Range 600 yards.

An aftercast of the probable weather conditions on the approach to Gatwick from 10 miles west to the threshold of Runway 09 is as follows:-
(All heights are above mean sea level)
The surface wind was calm or light westerly and from the western limit of the area under consideration to about 2.5-3 miles from the threshold of Runway 09 the ground was almost entirely covered with fog. The top of the fog was about 650 to 700 feet and the visibility within it varied from about 30 to 200 yards. It is possible that there were a few transient isolated breaks.
From the eastern edge of the fog belt to Gatwick there was mist and haze with visibility 1,500-2,000 yards and little or no low cloud.

Meteorological observations over Crawley showed that there was a temperature inversion from 400 to 2,900 feet and another from 6,000 to 6,400 feet. Reports from pilots flying between London and the vicinity of Gatwick indicate that below the second inversion, above the fog, the visibility was reduced by haze to 1,800 to 2,000 yards. Several pilots were able to see the ground during the last 2 or 3 miles of their approach to Runway 09 at Gatwick.

(d) Gatwick Airport

(i) General
Gatwick Airport is located about 25 miles south of London.
There is one concrete runway 7,000 feet long and 150 feet wide for use in either an easterly (Runway 09) or westerly (Runway 27) direction. The airfield elevation is 194 feet above mean sea level.
At the time of the accident Runway 09 was in use.

(ii) Lighting
In conjunction with Runway 09 the following lights were in use:-

a) Approach lights - A Calvert system 3,000 feet long with 5 cross bars of white high intensity lights.

(b) Runway Alignment beacon - A red light 10,850 feet from the threshold of the runway, flashing 18 times a minute.

(c) Threshold lights - A row of green lights delineating the threshold of the runway with wing bars either side of the threshold.

(d) Runway lights - High intensity white lights delineating the edges of the runway.

All the lights were at 100% brilliancy at the time of the accident.

(iii) Obstruction
Trees on high ground lying across the approach to Runway 09 1.5 to 3 nm. west of the airport up to 276 feet above aerodrome level. A hazard beacon is situated on this high ground.

(iv) Radio Navigational facilities
Radio Navigational facilities provided for use in conjunction with Runway 09 are:-

(a) The Instrument Landing System (ILS)

(b) Ground Controlled Approach (GCA)

(c) Non-Directional Beacon (NDB)

Full descriptions of these facilities may be found in the U.K. Air Pilot.

(e) The Flight
The aircraft left Rome at 1302 hrs on the day of the accident. According to the Air Traffic Control Flight Plan its destination was London Airport and its declared alternate Paris (Orly). Before leaving, the Captain was supplied with the weather forecast folder for the route. The flight was expected to take 3 hours 16 minutes and the endurance of the aircraft was 6.5 hours.

TC-SEV called London Airways at 1556 hrs. after passing Abbeville and was cleared by ATC to the Epsom Radio Range station, the holding point for London Airport, on a QNH of 1046 mb. A change of QNH to 1044 mb. was broadcast at 1610 hrs.

During the incoming flight of this aircraft the Commandant at London Airport had maintained a 'flight watch' on it. As a result of the very poor weather conditions prevailing at the airport a large number of incoming aircraft had diverted. The Commandant had been in continuous touch with the Meteorological forecaster who, at 1600 hrs, had expressed the opinion that the slight improvement which was taking place at the time would not be maintained and that the visibility could quickly fall to 300 yards or less and that Gatwick would probably retain a visibility of about 1 mile until about dusk. After discussing the situation with the Airport Commandant at Gatwick the Commandant London Airport decided to inform the Turkish Captain that he should divert to Gatwick, where arrangements had been made for his passengers to be met. A message to this effect was passed and acknowledged at 1620 hrs.

At 1621 hrs the aircraft reported over the Epsom range and asked for, and was given, diversion instructions. At 1627 hrs it left Epsom for Mayfield, the holding point for Gatwick, where it was informed by Gatwick Approach Control that it would be positioned by radar for an ILS approach to Runway 09. To this the aircraft replied "Thank you". The latest weather report for Gatwick was given as wind calm, visibility 1.1 nm, mist, cloud 3 oktas at 600 feet, QFE 1036 mb. Radar Director 1 operating No. 1 Plan Position Indicator (PPI) identified TC-SEV over Mayfield NDB at 4,000 feet and instructed it to steer a course of 280 and to descend to 2,000 feet. This was acknowledged. The aircraft was then told to change radio frequency to that of Gatwick (Radar) Director 2. The communications on this frequency were not electrically recorded. (See Observation (b) para. 4).

According to the recollections of Director 2, clearance was given for a descent to 1,500 feet on a QFE of 1036 mb. What appeared to be a normal radar positioning was carried out, the aircraft overshooting the centre line slightly as it turned on to the ILS approach path. At 5nm from touchdown, in reply to a query from Director 2, the aircraft affirmed that it could continue on the ILS. TC-SEV was then asked to change to tower frequency and this request was acknowledged. This was the last communication with the aircraft. Director 2 has affirmed that the speaker's English was good, that he seemed to comprehend his instructions, and that he appeared to be familiar with the procedures.

The blip representing the aircraft continued along the approach path centre line on the radar screen towards the runway until it faded and disappeared about 3nm from the threshold. Radio calls to the aircraft brought no reply and it was assumed that an accident had occurred.

The local fire and rescue services were alerted and soon it was confirmed that the aircraft had crashed in Jordan's Wood near the place indicated by the fading of the blip.

(f) Inspection at the Scene of the Accident
Inspection at the scene of the accident showed that the aircraft had flown into the tops of trees 390 feet above mean sea level at the edge of Jordan's Wood east of the Newdigate-Rusper road on a heading parallel to the approach path to Runway 09 at Gatwick. The site of the accident is 2.8 nm. from the runway threshold and 550 feet to the north of the approach path centre line. Photographs taken at the scene of the accident are at Appendix I.

The aircraft began to disintegrate as it descended through the trees at an angle of about 6 degrees from the horizontal until the wheels made contact with the ground. After rising again slightly the main part of the wreckage came to rest about 100 yards further on and then caught fire. A few minutes later an explosion occurred in which the stewardesses and the steward, who are believed to have re-entered the passenger cabin to assist the occupants, became casualties.

The wreckage trail extended over some 250 yards. An inspection of the wreckage, the sequence of disintegration and the impact marks on the trees and ground indicated that at the moment of striking the trees the aircraft was slightly right wing low and in the configuration associated with the early stages of an approach to land. Except for the low height there was no indication of any unusual circumstance.

Destruction of the flight deck and equipment had begun early in the sequence of disintegration and was complete when the wreckage came to rest. Two altimeter dials were recovered and the subscale of one was found to be set to 1044 mb, the QNH. There was some indication that the subscale of the other had also been set to the QNH. but the dial was damaged and the reading was considered to be unreliable.

(g) Subsequent Examination of the Wreckage
The wreckage was removed to the Accidents Investigation Branch hangar and laid out for detailed examination. This examination extended over several weeks. All the airframe and engine services and the electrical and mechanical equipment for operating them were removed and examined. The undercarriage was found to have been locked down and the flaps set to 20 . The trim tabs showed that a small amount of nose down and left wing low trim had been applied. The engines and propellers had been operating normally. No evidence was found of any pre-crash structural defect or mechanical failure in the aircraft, engines or equipment.

Special examination of the severely damaged ILS equipment indicated that the ILS localiser receiver had been tuned to the correct frequency. No useful information could be obtained from the remains of the glide path receiver.
From the remains of the ADF equipment it was possible to establish that No. 1 ADF set had been tuned to a frequency of 360 kcs. Stations closest to this frequency are Dunsfold Radio Range (357 kcs) and Gatwick Locator NDB (365 kcs). No. 2 ADF was tuned to a frequency of 185 kcs. The only station with a frequency close to this which is considered relevant is Ankara Broadcast Station (182 kcs).

(h) Subsequent examination of radio facilities
Flight checks of the radio aids at Gatwick took place the morning after the accident. In addition a special flight check was carried out at the request of the Turkish Technical Delegation. All these tests showed that the ground radio equipment at Gatwick was working correctly.
The statements of pilots using the ILS on Runway 09 immediately before and immediately after the accident indicate that it was functioning normally.

4. OBSERVATIONS

(a) In an endeavour to establish the track of the aircraft after it left the Mayfield beacon a widespread search for eye-witnesses was carried out. No one was found who could testify to having seen the aircraft. While this was no doubt due to the weather conditions prevailing at the time of the accident a considerable number of persons interviewed heard an aircraft flying - most say very much lower than normal - in their vicinity. Circumstantially it is believed that this aircraft was the Turkish Viscount. From a consideration of the evidence available from all sources a reconstruction of the probable track of the aircraft was made and this is shown at Appendix II.

(b) During maintenance of the recording equipment at Gatwick on 2nd February, 1959, certain components, outwardly similar, were changed over for test purposes. They were not replaced in their original positions. As a result the radio communications on frequency 128.9 (Gatwick Director 2) were not electrically recorded. In spite of the regular inspections called for in the Maintenance. Instructions this situation remained undetected until the post-accident inspection on 17th February, 1959. This matter was the subject of a Departmental inquiry.
The absence of a recording of this final and vital stage of the flight hampered the investigation. There is no reason to suppose however that the recollections of Director 2, from whom a statement was taken in the early hours of the following morning and before he was aware that his communications with the aircraft had not been electrically recorded, were other than materially correct.

(c) It has not been possible to establish what the aircraft's manoeuvres in altitude were during the concluding stage of the flight. The radar equipment (P.P.I.) in use at the time does not provide height information. Captain Ozbek's intentions in respect of the final approach must be a matter for conjecture. Survivors have said, that no unusual occurrence or manoeuvre took place and that none of the crew appeared to be disturbed or in any way apprehensive. The evidence indicates that the aircraft was under the control of the crew when the accident occurred. Several hypotheses as to how the pilots may have been misled by false radio signals or indications, or by sensory illusion resulting from the appearance of a light or lights in the fog, have been explored; no evidence to support any of these theories was discovered.

During discussions with the Turkish Technical Delegation about the use and availability of radio aids in Turkey it transpired that Captain Ozbek may have been using the ADF equipment as his primary approach aid. Whatever aid Captain Ozbek was using it seems clear that the final approach to land was not related to the ILS glide path and it may be that the pilots flying in a foreign country over unfamiliar terrain and confronted with a diversionary landing in poor weather conditions became involved in a task which was beyond their training and experience.

CONCLUSIONS

(i) The aircraft had a valid Certificate of Airworthiness and was properly maintained.

(ii) The all-up weight and trim of the aircraft were within the prescribed limits.

(iii) The crew was properly licensed.

(iv) There was no pro-crash malfunctioning of the aircraft, its engines or its equipment.

(v) All the ground facilities were serviceable and functioning correctly.

6. OPINION

The evidence is insufficient to establish the cause of the accident. There is no indication however that this can be associated either with a technical failure of the aircraft or with a failure of the ground services.


P. G. TWEEDIE

Chief Inspector of Accidents
Accidents Investigation Branch Ministry of Aviation
10th December, 1959

 

Appendix

 

POINT AT WHICH AIRCRAFT ENTERED THE TREES

 

VIEW IN DIRECTION OF DESCENT THROUGH THE TREES

 

 

 

RECORDING OF AERODROME APPROACH CONTROL COMMUNICATIONS AIRCRAFT TURKISH AIRLINES TC-SEV

OPERATION OF RECORDER Continuous

 

TO FROM RECORDED INTELLIGENCE TIME (GMT) REMARKS
GATWICK APPROACH TC-SEV (PCB) GATWICK GATWICK THIS IS TANGO CHARLIE SIERRA ECHO MIKE VICTOR 1632  
         
TC-SEV GATWICK APPROACH ERM ECHO VICTOR GATWlCK COME IN    
         
GATWICK APPROACH TC-SEV ER GATWICK ECHO VICTOR FROM EPSOM TO MAYFIELD ESTIMATING MAYFIELD AT THREE FOUR AT SIX THOUSAND FEET VICTOR MIKE AT THE MOMENT    
         
TC-SEV GATWICK APPROACH -CHO VICTOR MAINTAIN SIX THOUSAND FEET TO MAYFIELD THIS WILL BE RADAR POSITIONING FOR I L S FINAL APPROACH RUNWAY ZERO NINE   "CHO" End of word
         
GATWICK APPROACH TC-SEV THANKYOU    
         
TC-SEV GATWICK APPROACH VICTOR THE GATWICK WEATHER SURFACE WIND CALM VISIBILITY ONE DECIMAL ONE NAUTICAL MILES MIST THREE OKTAS AT EIGHT HUNDRED FEET THE Q F E ONE ZERO THREE SIX    
         
GATWICK APPROACH TC-SEV UNDERSTAND VIS' IS ONE DECIMAL ONE NAUTICAL MILES THREE EIGHTHS AT EIGHT HUNDRED FEET Q F E ONE ZERO THREE SIX (PCC) 1633  
         
TC-SEV GATWICK APPROACH 'FIRMATIVE THE CLOUD IS THREE OKTAS AT EIGHT HUNDRED EIGHT ZERO ZERO FEET    
         
GATWICK APPROACH TC-SEV THANKYOU    
         
TC-SEV GATWICK APPROACH —— GO ECHO VICTOR AIR- ER GATWICK DO YOU READ   "GO" End of word.
         
GATWICK APPROACH TC-SEV ECHO VICTOR GO AHEAD    
         
TC-SEV GATWICK APPROACH VICTOR DESCEND NOW TO FIVE THOUSAND FEET CHECK LEAVING SIX    
         
GATWICK APPROACH TC-SEV VICTOR LEAVING SIX AT THE MOMENT    
         
TC-SEV GATWICK APPROACH VICTOR    
    (PCD) 1634 Channel quiet
    RECORDER CHECK    
         
TC-SEV GATWICK APPROACH —— GO ECHO VICTOR DO YOU READ   "GO" End of word
         
GATWICK APPROACH TC-SEV GO AHEAD    
         
TC-SEV GATWICK APPROACH VICTOR ON REACHING MAYFIELD DESCEND IN THE HOLDING PATTERN TO FOUR THOUSAND FEET AND THEN LEAVE MAYFIELD ON A HEADING OF TWO EIGHT ZERO AND ADVISE    
         
GATWICK APPROACH TC-SEV VICTOR UNDERSTAND I DESCEND TO FOUR THOUSAND FEET ON THE HOLDING PATTERN OVER MAYFIELD THEN TO PROCEED TWO EIGHT ZERO DEGREES    
         
TC-SEV GATWICK APPROACH THAT'S AFFIRMATIVE ON REACHING FOUR THOUSAND FEET AT MAYFIELD LEAVE ON A HEADING OF TWO EIGHT ZERO    
         
GATWICK APPROACH TC-SEV 0 K    
    TIME SIXTEEN THIRTYFIVE (PCE) 1635  
         
GATWICK APPROACH TC-SEV ER WE ARE OVER MAYFIELD AT THE MOMENT AND NOW THEN TO PROCEED ON THE HOLDING PATTERN AND DESCEND TO FOUR THOUSAND FEET    
         
TC-SEV GATWICK APPROACH -CHO VICTOR   "CHO" End of word
         
TC-SEV GATWICK DIRECTOR TANGO ECHO VICTOR THIS IS GATWICK DIRECTOR YOU ARE IDENTIFIED OVER MAYFIELD CONTINUE YOUR LEFT TURN ONTO TWO EIGHT ZERO NOW OVER    
         
GATWICK DIRECTOR TC-SEV ER ROGER UNDERSTAND WE CONTINUE TO LEFT TURNING TWO EIGHT ZERO    
         
TC-SEV GATWICK DIRECTOR —GER AND CONTINUE YOUR DESCENT TO TWO THOUSAND FEET ADVISE PASSING FIVE (PCF) FOUR AND THREE 1636 "GER" End of word
         
GATWICK DIRECTOR TC-SEV ER ROGER UNDERSTAND THE PRESENT TIME WE ARE AT FOUR THOUSAND FEET AND CONTINUE TO DESCEND TO TWO THOUSAND AND WILL ADVISE AT THREE    
         
TC-SEV GATWICK DIRECTOR —GER   "GER" End of word
    (PCG) 1637 Channel quiet
GATWICK DIRECTOR TC-SEV ECHO VICTOR CROSSING THREE THOUSAND    
         
TC-SEV GATWICK DIRECTOR ECHO VICTOR ROGER    
         
TC-SEV GATWICK DIRECTOR TANGO ECHO VICTOR CALL DIRECTOR NOW ONE TWO EIGHT DECIMAL NINE IF NO CONTACT REVERT HERE OVER    
         
GATWICK DIRECTOR TC-SEV ER WILL YOU SAY THE FREQUENCY AGAIN PLEASE    
         
TC-SEV GATWICK DIRECTOR ONE TWO EIGHT DECIMAL NINE    
         
GATWICK DIRECTOR TC-SEV ER ROGER ONE TWO EIGHT DECIMAL NINE    
    (PCH) 1638 Channel quiet

 

I certify that this extract, consisting of 4 sheets each of which bears my signature, from the Radio telephony Recording Log kept at Gatwick Airport by the Ministry of Transport and Civil Aviation has been prepared under my direction and has been examined and checked by me; that column 4 thereof is a transcription of the recording believed by me to be accurate in all respects; and that column 5 contains a correct interpretation of the time signals appearing in code in column 4.

Signature

23rd February, 1959.