1963 BAC One-Eleven test crash

1963 BAC One-Eleven test crash

A BAC 1-11 in British Aircraft Corporation livery similar to the accident aircraft.
Occurrence summary
Date	22 October 1963
Summary	Deep stall
Site	Near Chicklade, Wiltshire, England, United Kingdom 51°07′23″N 2°08′20″W / 51.123°N 2.139°W / 51.123; -2.139Coordinates: 51°07′23″N 2°08′20″W / 51.123°N 2.139°W / 51.123; -2.139
Crew	7
Fatalities	7
Survivors	0
Aircraft type	BAC One-Eleven 200AB
Operator	British Aircraft Corporation
Registration	G-ASHG

The 1963 BAC One-Eleven test crash was a fatal accident of a British Aircraft Corporation prototype aircraft on 22 October 1963, near Chicklade in Wiltshire, England while it was undertaking a test flight. All seven crew members on board the BAC One-Eleven were killed.

The accident occurred during a test flight of the first prototype BAC One-Eleven (registration G-ASHG) which had taken off from Wisley Airfield with seven crew on board, piloted by Mike Lithgow. The aircraft was on its fifth test flight to assess stability and handling characteristics during the approach to–and recovery from–a stall with the centre of gravity in varying positions. From an altitude of 16,000 feet (4,900 m) and with the flaps extended 8°, the aircraft entered a stable stall with it descending at a high rate in a horizontal attitude, eventually striking the ground with very little forward speed. The aircraft broke up on impact at Cratt Hill, near Chicklade, a small village in southern Wiltshire and caught fire, killing all seven crew on board.

The aircraft was on its fifth stalling test of the day, and the crash occurred 23 minutes after takeoff from Wisley. The crew were Lt. Cdr. M J Lithgow OBE, Chief Test Pilot; Capt. R Rymer (Test Pilot); B J Prior (Aerodynamicist); C J Webb (Designer); R A F Wright (Senior Observer); G R Poulter (Observer) and D J Clarke (Observer).

The cause of the accident was the aircraft entering a stable stalled condition, recovery from which was impossible due to the wings blocking the airflow over the elevators on the tail. This was the first accident to be attributed to the phenomenon known as deep stall, peculiar to rear engine T-tailed aircraft.

Once the condition of deep stall was recognized, relatively simple preventative measures were introduced, including stick-shakers indicating an approaching stall and stick-pushers which automatically operate the elevators and physically lower the nose before the stall is reached, while the tailplane and pitch controls are still effective.