What happened
On January 17, 2009, an ATR 42-500, registration F-GVZB, operated by Airlinair, was performing a chartered flight from Lyon Bron to La Rochelle. The flight was carrying a rugby team, which resulted in a significantly higher passenger mass than standard estimates. Prior to departure, the aircraft underwent Type II anti-icing treatment due to frost on the wings and fuselage.
During the takeoff roll, as the aircraft reached a speed of 110 knots (the selected V1 and VR), the pilot attempted to rotate the aircraft. Upon pulling back on the elevator, the pilot encountered abnormally high control forces. Following a pre-flight briefing regarding similar phenomena after anti-icing, the crew attempted to apply the stabilizer trim to nose up. However, the nose failed to lift. At approximately 120 knots, the pilot decided to abort the takeoff, applying reverse thrust and bringing the aircraft to a stop on the runway. There were no injuries or fatalities during the incident.
The investigation
The BEA investigation focused on the aircraft's weight and balance, the effects of the anti-icing fluid, and the crew's decision-making. Investigators examined the load sheet, which had been calculated using standard passenger weights, and noted that the actual mass of the rugby players and their cabin baggage was approximately 300 kg higher than estimated.
Data from the Quick Access Recorder (QAR) was analyzed to determine the elevator movement. The investigation also reviewed the anti-icing procedures and the crew's application of the stabilizer trim. While the crew initially suspected the heavy control forces were a known side effect of anti-icing fluid, the investigation established that the physical cause was actually related to the aircraft's center of gravity.
Findings
- The primary cause of the heavy control forces was an out-of-limits forward center of gravity at takeoff.
- The aircraft's center of gravity index was at the forward operational limit due to the high mass of the passengers and the insufficient distribution of baggage in the aft compartment.
- The passenger mass was underestimated because the standard weight assumptions did not account for the significantly larger physique of the rugby players.
- The crew initially attributed the control difficulty to the anti-icing fluid, which delayed the recognition of the true weight and balance issue.