What happened
On August 30, 1975, a LOT Polish Airlines Tu-134, registration SP-LGE, was operating a scheduled flight from Warsaw to Zurich. The aircraft, carrying 72 passengers and 6 crew members, was performing an ILS approach to runway 16. During the approach, the crew extended the landing gear and performed the necessary checklists. The flight technician reported that the gear was down and locked, with all three green indicator lights visible.
As the aircraft neared touchdown, the pilot reduced power to idle. At this moment, the landing gear warning horn sounded. The captain, determining that the aircraft was at an insufficient altitude (approximately 1.5 to 2 meters) to safely execute a go-around, continued the landing. Upon touchdown, the nose of the aircraft dipped lower than normal. The captain immediately ordered the engines to be shut down, deployed fire extinguishers, and cut the electrical power. While the crew attempted to keep the nose elevated during braking, the unlatched nose gear collapsed. The aircraft slid approximately 320 meters along the concrete runway before coming to a halt near the intersection with runway 28. There were no injuries to the passengers or crew, and the aircraft sustained only minor damage.
The investigation
Investigators examined the aircraft's flight data recorder and the mechanical condition of the landing gear system. Analysis of the flight data revealed that while the main landing gear had been properly extended and locked, the nose gear was only partially extended at the time of the accident. A photograph taken from the ground near the middle marker showed the gear doors open and the nose gear in an intermediate position.
Technical inspections of the landing gear control switch revealed significant wear on the internal mechanism, specifically in the 'Neutral' position. This wear made it easy for the switch to be accidentally moved past 'Neutral' into the 'UP' position. Furthermore, investigators found that the flight technician's 'Final Check' lacked a formal, standardized checklist, relying instead on unwritten procedures.
Findings
- The primary cause of the accident was the partially retracted nose gear resulting from an unnoticed error by the flight technician during the final approach checks.
- The worn condition of the landing gear selector switch contributed to the error, as the lack of a clear tactile or visual indication in the 'Neutral' position allowed the switch to be inadvertently moved to the 'UP' position.
- The crew's attention was focused externally during the final moments of the approach, preventing them from noticing the nose gear indicator light turning off.
- The absence of a mandatory, non-interruptible landing gear warning system that activates upon flap extension was a contributing factor.