What happened
On June 17, 2003, an Onur Air MD-88 was performing a take-off at Groningen Airport Eelde. During the initial stages of the roll, the crew received an acoustic alert indicating an incorrect setting for the longitudinal control system trim. The crew briefly interrupted the take-off to check the systems; finding no obvious issues, they resumed the roll. However, as the aircraft accelerated, the warning signal repeated. The crew ignored this second alert and continued the take-off.
As the aircraft approached rotation speed, the captain noticed that the control force required to rotate the aircraft was significantly higher than normal. He subsequently decided to reject the take-off at a late stage. Because the decision was made after passing the V1 speed, the remaining runway was insufficient to bring the MD-88 to a halt. The aircraft overran the runway end, colliding with approach lights and underground concrete structures before coming to a stop in soft soil. There were no serious injuries among the 142 passengers and 7 crew members on board.
The investigation
The investigation focused on the aircraft's trim settings, the accuracy of the weight and balance calculations, and the effectiveness of the emergency evacuation. Technical analysis, including a study by Boeing, revealed that the stabilizer was significantly mis-trimmed, which created much higher control column forces than the pilot could effectively manage for a normal rotation.
Investigators also examined the aircraft's loading. It was determined that the actual center of gravity was much further forward than the crew had calculated. Furthermore, the investigation reviewed the evacuation process, noting that the cabin crew's instructions were not sufficiently clear and that some passengers attempted to retrieve hand luggage, which hindered the speed of the exit.
Findings
- The primary cause of the difficult rotation was a stabilizer gross mis-trim of approximately 5 degrees.
- The actual center of gravity was located much further forward than the crew's calculated values.
- The crew failed to stop the take-off after the first warning and chose to ignore the repeating acoustic alert signal.
- The take-off was rejected at a stage where the remaining runway length was insufficient to stop the aircraft.
- The evacuation was hampered by unclear communication from the cabin crew and the use of only some available exits.
Safety action
Following the accident, Onur Air implemented internal measures after reviewing the findings. The investigation highlighted the critical danger of ignoring cockpit warning systems and the necessity for more robust methods to verify aircraft loading and center of gravity accuracy.