Summary
On 22 June 1970 at 0842 GMT, a Pilatus Turbo Porter HB-FCW crashed shortly after takeoff from a desert airstrip at oil concession HH.l/82 in the Libyan Sahara. The aircraft entered a left turn from a height of 45 meters, stalled, and impacted the ground. The pilot was killed and the aircraft destroyed. The accident was determined to have occurred because the pilot took off without first removing the gust locks from the right aileron.
Investigation
The accident was reported the same day by Pilatus Flugzeugwerke AG to the Swiss Bureau for Aircraft Accident Investigation. Libyan authorities sent a telex on 23 June 1970. The chief engineer of Pilatus arrived in Libya on 29 June and conducted initial ground surveys. A Swiss investigator visited the site from 3 to 8 July 1970, gathering information from Air Libya in Benghazi and Libyan civil aviation authorities in Tripoli. A key witness was interviewed on 8 August 1970 in Parma, Italy. Microanalytical examination of the gust locks and right wing parts was commissioned from the Zurich City Police Scientific Service, with results submitted on 23 November 1970.
Elements
Pilot
The pilot, born 1943, was an Austrian national holding a Swiss professional pilot license issued on 20 January 1967, valid until 2 August 1970. He had 1813 total flight hours, including 313 on the accident type. In the three months prior, he flew 246 hours on the type. He had a rest period of three days before the accident. His last medical examination was on 2 February 1970 in Graz, with no limitations noted.
Aircraft
The aircraft was a Pilatus PC-6/B1-H2 Turbo Porter, serial number 638, built in 1967. It was owned and operated by Pilatus Flugzeugwerke AG. The engine was a Pratt & Whitney PT-6A-20 turboprop. The accident flight was solo with no cargo. Weight and balance were within limits.
Terrain
The accident site was at oil drilling concession HH.l/82, in sand dunes of the Libyan Sahara. The airstrip, marked with empty barrels, was 300 m long and 50 m wide, oriented 17/35. A windsock was present at the threshold of Runway 17.
Weather
Witnesses reported sunny, cloudless conditions, easterly wind at 5–10 knots, temperature 32°C, sun elevation 65°.
Regulations
The Swiss regulations on commander duties require pre-flight preparation. The Airplane Flight Manual specifies control unlocked, free, and full travel before starting engine.
Flight Sequence and Accident
At 0815 GMT on 22 June 1970, a radiotelephone message reported an accident at another concession requiring medical transport. The pilot and a surveyor drove to the aircraft, which was parked at the threshold of Runway 17. The surveyor assisted in removing gust locks from the left wing and placed them in a box. The pilot worked on the right wing and tail. After pre-flight checks, the aircraft taxied into position and remained stationary for about three minutes before takeoff.
Shortly after lifting off, the aircraft immediately turned left, with the left bank angle increasing to nearly 90°. It lost altitude, circled around the drilling tower, and struck the ground left wing first, then overturned and caught fire.
Damages
The pilot was killed. The aircraft was destroyed. No third-party damage occurred.
Subsequent Findings
The day after the accident, an Air Libya mechanic found two gust locks near the right wing: one near the aileron-flap gap and another 21 m from the wreckage connecting the wingtip to the aileron. Other locks were found burned in the cockpit debris. The chief engineer of Pilatus confirmed these findings. A trailing arm from the right aileron gust lock was found in the sand behind the aileron-flap joint.