Accident Overview
A scheduled passenger flight from Frankfurt was conducting an ILS approach for a night landing on Runway 27 at Gatwick Airport. Weather conditions were clear except for freezing fog persisting in some areas, including Gatwick. The runway visual range (RVR) was 100 metres. The approach was initiated with the autopilot coupled to the ILS. After capturing the glide slope, the commander, who was at the controls, disconnected the autopilot because the "stabiliser out of trim" warning light illuminated.
Sequence of Events
At the outer marker, the flap setting was changed from 1° to 30°. Shortly thereafter, the rate of descent increased, and the aircraft descended below the glide slope. When approximately 200 feet above ground, the pilot realized the aircraft was too low and initiated a missed approach. The aircraft began to respond, but the descent was not arrested in time to avoid a collision with trees and a house. The impact destroyed both the aircraft and the house, and the wreckage caught fire. Forty-eight occupants of the aircraft and two people in the house were killed; 14 others were injured. The aircraft was totally destroyed by impact forces and a post-crash fire.
Investigation Findings
The official investigation determined that the accident resulted from the commander inadvertently allowing the aircraft to descend below the glide slope during the final stage of an approach to land until it was too low for recovery. Specific findings reported include:
- The deceptive nature of the weather conditions led the commander to an error of judgment in deciding to make an approach to Gatwick.
- The commander's decision to conduct an approach was not in itself a cause of the accident.
- Incorrect flap configuration at glide-slope interception led to a temporary out-of-trim condition during the automatic approach and illumination of the stabilizer "out-of-trim" warning light.
- The commander interpreted the warning light as indicating a possible malfunction and disconnected the autopilot.
- Out-of-sequence and late selection of 30° flaps from 15° while the aircraft was being flown manually resulted in an increased rate of descent, causing the aircraft to go rapidly below the glide slope.
- The commander did not become aware of the deviation from the glide slope until it was too late to effect full recovery.
- The pilot's attention was probably directed outside the aircraft at the critical time in an attempt to discover sufficient visual reference to continue the approach rather than to the flight instruments.
- Monitoring by precision approach radar would have warned the pilots of the deviation in time, if corrective action was taken promptly, to avoid the accident.