What happened
On November 3, 1994, an Air Liberté Tunisie DC-9-83 (MD-83), registration F-GHED, was performing a commercial flight at Kajaani Airport when it experienced a significant runway excursion. The aircraft touched down approximately 600 meters beyond the normal touchdown point at a high speed of roughly 26 knots above the target speed. During the landing roll, the nose gear contacted the runway first, which is highly unusual for this aircraft type.
Following the touchdown, the aircraft's main landing gear began to vibrate violently. This intense vibration caused the failure of the bolts and nuts in the landing gear pivot pins. As the aircraft continued to slide, it veered off the runway to the right, primarily because only the brakes on the right main gear remained functional. During the excursion, the aircraft's left forward door mechanism jammed due to fuselage twisting, and a puncture in the left wing spar resulted in a fuel leak of approximately 400 liters.
Despite the heavy damage to the airframe and landing gear, all 164 passengers and 7 crew members survived, with only 3 passengers sustaining minor injuries.
The investigation
The investigation focused on the sequence of events during the final approach and the technical failure of the landing gear. Investigators examined the cockpit voice recorder and flight data recorder to reconstruct the crew's actions. The inquiry looked into the deployment of spoilers, the use of engine thrust, and the effectiveness of crew resource management (CRM).
Technical inspections revealed that the spoilers failed to deploy upon touchdown. This was attributed to the high engine power setting (specifically the left thrust lever position), which prevented the automatic spoiler deployment. Furthermore, the investigation examined the structural integrity of the landing gear and the cause of the intense vibrations that led to the mechanical failure of the gear components.
Findings
- The primary cause of the accident was a series of pilot errors related to engine thrust and spoiler deployment.
- An accidental activation of the TOGA (Takeoff/Go-Around) button caused an immediate increase in engine power, which the crew failed to correct.
- The crew performed a task handover at approximately 150 feet, a procedure for which the pilots had not received specific training and which the airline had no established standard methods for.
- The monitoring pilot failed to oversee the deployment of the spoilers or notice the changes in flight director and automatic thrust settings.
- High-intensity approach and runway lights may have caused a visual illusion regarding the aircraft's altitude just before the task handover.
- The heavy vibration of the main landing gear, a known risk for this type under high-speed, non-spoiler deployment conditions, led to the structural failure of the gear assembly.