Air Inter Flight 148

Air Inter Flight 148  was a scheduled airline flight on 20 January 1992 that crashed in the Vosges Mountains, near Mont Sainte-Odile, while circling to land at Strasbourg Airport. Only 9 people onboard survived.

Accident
Flight 148, commanded by Captain Christian Hecquet and First Officer Joël Cherubin, departed Satolas Airport (now known as Lyon-Saint Exupéry Airport) in Lyon, France. While being vectored for a VOR DME Approach to Runway 05 at Strasbourg, it crashed at 19:20:33 CET (18:20:33 UTC) in the mountains at an altitude of 2,620 feet (800 m).

The pilots had no warning of the imminent impact because Air Inter had not equipped its aircraft with ground proximity warning systems (GPWS). This was because Air Inter – facing ferocious competition from France's TGV high-speed trains – encouraged its pilots to fly fast at low level (up to 350 knots below 10,000 feet, while other airlines generally do not exceed 250 knots), and GPWS systems gave too many nuisance warnings.

Flight 148 was the third in a series of crashes caused at least in part by what was believed to be pilots' unfamiliarity with the sophisticated computer system of the Airbus A320. The Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) believe that Flight 148 crashed because the pilots inadvertently left the autopilot set in Vertical Speed mode (instead of Flight Path Angle mode) then entered "33" for "3.3° descent angle", which the autopilot interpreted as a descent rate of 3,300 feet (1,000 m) per minute.

Accident investigators determined that there was no single cause of the accident, as there were multiple factors that contributed to the crash, such as the air traffic controller incorrectly warning the crew that they were to the "right" of the runway. When investigators input this descent rate into a flight simulator, the simulated plane did not crash. Further investigation showed that after some small turbulence, a safety feature in the autopilot further increased the descent thus adding to the chain of events that caused the crash.

Aftermath
Accident investigators recommended 35 changes in their report. Airbus modified the interface of the autopilot so that a vertical speed setting would be displayed as a four-digit number, preventing confusion with Flight Path Angle mode. The flight data recorder was upgraded so that it was able to withstand higher temperature fires, and for longer. Pilot training was increased for the A-320.

Dramatization
The story of the disaster was featured on the ninth season of Canadian National Geographic Channel show Mayday (known as Mayday in North America and Air Crash Investigations in the UK, Australia and the rest of world). The episode is entitled "Crashed and Alone."