What happened
On February 7, 1991, an Air France Airbus A320, registration F-GFKI, was performing a ferry flight from Nîmes-Garons to Paris Charles de Gaulle. Due to deteriorating weather conditions involving snow, the crew had decided to terminate the day's training session and return to Paris.
Prior to takeoff, the aircraft performed a turnaround on the runway overrun area (prolongement d’arrêt). As the pilot applied takeoff power, the high-velocity exhaust from the engines caused the asphalt pavement of the overrun area to tear away. Fragments of the pavement were projected backward, striking the aircraft's horizontal stabilizer.
During the climb, as the aircraft reached approximately 4,150 feet, the crew activated the wing anti-ice system. This activation coincided with intense vibrations felt throughout the airframe. While the crew initially attributed these vibrations to the anti-ice system, passengers in the rear of the cabin noticed that a portion of the right horizontal stabilizer tip was missing and alerted the crew. The flight continued to its destination at a reduced altitude and speed, with no further incidents reported.
The investigation
The investigation focused on the structural integrity of the overrun area and the sequence of events leading to the stabilizer damage. Investigators examined the pavement, finding that approximately 180 square meters of the surface had been stripped away in two symmetrical zones.
Technical analysis of the horizontal stabilizer revealed that fragments of asphalt and binder had impacted the underside and elevators, causing structural weakening. The investigation also looked into why the crew was unaware of the ground damage. It was established that while ground personnel observed the debris being projected behind the aircraft, this information was communicated verbally to the control tower but was never relayed to the flight crew.
Findings
- The primary cause of the accident was the application of takeoff power while positioned on the overrun area, an use of the surface that exceeded its intended design purpose.
- The pavement of the overrun area was in a degraded state, making it particularly vulnerable to the extreme aerodynamic forces of the engine blast.
- The crew's ability to diagnose the damage was hindered because the ground observations regarding the torn pavement were not transmitted to the cockpit.
- The crew's initial assessment of the vibrations as being related to the wing anti-ice system prevented them from immediately recognizing the structural damage caused by the debris.