What happened
On October 18, 1999, a Saab 340A, registration OH-SAD, operated by Air Botnia, experienced an aborted takeoff on runway 21 at Mariehamn Airport. During the takeoff roll, the pilot flying (the captain) increased engine power, which triggered a "configuration" warning. Simultaneously, the pilot not flying (the co-pilot) reported that the control column was moving backward, claiming the aircraft was trimming itself nose-up.
In response to this perceived malfunction, the captain decided to abort the takeoff. The aircraft accelerated to 116 knots, exceeding the calculated V1 speed of 107 knots, before the crew applied brakes and reduced power. There were 13 passengers and 3 crew members on board, and no injuries or aircraft damage were reported.
The investigation
The investigation examined the aircraft's flight data recorder (DFDR) and technical components of the elevator trim system. Investigators found that the elevator trim had been left in a +6° nose-up position from the previous landing and had not been reset to the required +0.04° according to the loadsheet.
Analysis of the DFDR showed that while the trim did move, it shifted from -0.3° to +3.4° during the takeoff roll. The investigation also reviewed the airline's operational procedures, crew training, and previous safety reports. Technical experts from the aircraft manufacturer assisted in verifying that the control movements reported by the co-pilot were actually characteristic of the aircraft type under those specific conditions.
Findings
- The primary cause of the aborted takeoff was the co-pilot's report of uncommanded control movement, which was actually normal aircraft behavior for this type.
- The elevator trim was not reset to the correct takeoff setting (+0.04°) following the previous flight, remaining at +6° until the crew corrected it during the roll.
- There was a lack of coordination regarding trim settings, as the crew had different understandings of who was responsible for setting the trim.
- The co-pilot was relatively inexperienced in the right-hand seat of this aircraft type, having only completed a limited number of supervised sectors.
- The airline's rapid growth and high-pressure schedule contributed to a lack of familiarity with specific standard operating procedures (SOPs) and cockpit coordination.