On 17 June 2003, a crew of a Boeing MD-88, being operated by Onur Air, executed a high speed rejected take-off at a late stage which resulted in overrun of the runway and serious damage to the aircraft. The Take Off Configuration Warning System was sounding throughout the take off roll and was ignored. The joining passengers were allowed free seating.
This is an extract from the Report (investigation no. 2003071) on the accident published by the Dutch Safety Board.
"During take-off at a speed of approximately 130 kts the captain, who was pilot flying, rejected the take-off above the decision speed because he experienced a heavy elevator control force at rotation. The stabiliser warning sounded during the entire take-off roll. The aircraft overran the runway end and came to a stop in the soft soil. […] The aircraft was substantially damaged but there was no fire and no fatalities.
[…] The captain stated that after the aircraft was lined up on runway 23 the take-off was initiated. After the throttles were advanced, the stabiliser warning sounded. The throttles were retarded and the aircraft stopped. The captain stated that the aircraft had moved five to six meters before it stopped…Flight data recorder (FDR) data revealed that the aircraft … travelled …approximately 25 meters.
On the runway checks were performed. FDR data indicated a stabiliser position change from 6.8 to 7.2 degrees aircraft nose up (ANU). Thereafter the crew initiated a static engine spin-up. Again the stabilizer warning sounded. The crew released the brakes and started the take-off roll. From the CVR it is derived that during the entire take-off roll the warning sounded continuously.
When attempting to rotate the captain experienced a heavy elevator control force. The captain stated that he needed much more than normal back pressure on his control column to lift the nose. He felt ”it was impossible to make the take-off”, and as the nose did not rise he decided to reject the take-off. Post accident analysis revealed that the rejection was initiated at 128 knots.
In the Crew Interviews section, the Report States:
During the interview, the captain stated that no technical anomalies were known before flight, and that the anti-skid system had been serviceable. He stated that the warning sounded again at a speed of 100 knots. About the same observations and actions were mentioned by the co-pilot, whereby he characterized the warning as a stabilizer motion warning. The co-pilot acknowledged that it is company policy to reject the take-off when a take-off configuration warning occurs. The captain stated that he considered the warning as false and therefore continued the take-off. The captain recalled that the calculated rotation speed (Vr) was 135 kts. According to the co-pilot, the captain initiated rotation at 120 knots.
[…] During the accident flight, the standard speed calls “eighty” and “one hundred” by the PNF can be heard. The V1 call is not heard on the CVR.
[…]No “rotate” call is heard on the CVR. After the “one hundred” call the first officer said “It is not reached yet”, followed by the captain’s remark “It is not rotating”.
During the interview […] the captain recalled that the rotation speed was (Vr) was 135 kts. The co-pilot mentioned that the speed at which rotation was initiated was 120 knots. During rotation the captain experienced heavy control forces. When asked, both pilots did not know why the aircraft did not rotate.
In the Take-off mass, centre of gravity and stabilizer setting section, the Report states:
The take-off mass as derived from the load and trim sheet was 127,529 pounds. Investigation revealed a most probable take-off mass of approximately 130,000 pounds.
There was 2,000 pounds more fuel in the centre tank and 1,700 pounds less fuel in the wing tanks, creating a more forward effect on the TO-CG (centre of gravity during take-off) than assumed on the load and trim sheet. The passenger seating was not consistent with the load and trim sheet. Passengers were seated more forward than assumed. […] For this flight passengers were free to choose their seat (free seating policy).
The causal and contributory factors to the accident are identified as:
- The crew resumed the take off and continued whilst the take off configuration warning, as a result of the still incorrect stabilizer setting, reappeared.
- The actual center of gravity during take-off (TO-CG) was far more forward than assumed by the crew. As a consequence the horizontal stabilizer was not set at the required position for take-off.
- The far more forward TO-CG - contributed to an abnormal heavy elevator control force at rotation and made the pilot to reject the take-off beyond decision speed. This resulted in a runway overrun.
- By design the aircraft configuration warning system does not protect against an incorrect TOCG insert.
- The aircraft was not equipped with a weight and balance measuring system.
- Deviations of operational factors accumulated into an unfavourable aircraft performance condition during take-off.
- Cockpit crew showed significant deficits."
A number of Safety Recommendations are made in the Report of the Investigation on the subject of aircraft operations and airport management as well as several specific recommendations on the safety of non-EU aircraft operators' flights in EU airspace.