What happened
On 12 September 2003, a Saab-Scania SF340B, registration G-LGNG, was performing a scheduled passenger service from Aberdeen to Kirkwall. During the approach to Kirkwall Airfield, the flight crew noted that the aircraft felt unusual, specifically observing that they had run out of nose-down trim after selecting flaps 35°. Despite this, the crew decided to proceed with the landing.
Upon touchdown, the aircraft's pitch attitude was significantly higher than the recommended 4-5 degrees. As the crew retarded the power levers from FLIGHT IDLE toward GROUND IDLE, the nose began to rise rapidly. The aircraft's pitch increased to approximately 14 degrees, causing the ventral strakes to contact the runway surface. The crew attempted to apply full nose-down elevator, but the nose continued to rise until the stall warning activated. The pitch only began to reduce after the power levers were advanced back to the FLIGHT IDLE stop. There were no fatalities and no injuries among the 36 passengers or 3 crew members, though the aircraft sustained damage to the aft fuselage strakes.
The investigation
Investigators examined the aircraft's Flight Data Recorder (FDR) and cargo loading records. The FDR revealed that the aircraft touched down at a speed of Vref -20 kt with a high pitch attitude. The data showed that the elevator position was actually commanding further nose-up pitch at the moment of touchdown.
An audit of the baggage loading revealed that the actual weight of the passenger luggage exceeded the weight stated on the loadsheet by 215 kg. This discrepancy was caused by the use of a standard mass for all bags rather than actual weights, and the fact that some weights were estimated to expedite check-in. Furthermore, due to space constraints in the C1 hold, more baggage was placed in the C2 compartment than planned, which shifted the aircraft's centre of gravity beyond the permitted aft limit.
Findings
- The primary cause of the tail strike was the mis-loading of baggage, which resulted in the aircraft operating with a centre of gravity beyond the aft limit.
- The aircraft was 85 kg above the maximum allowable take-off weight.
- The nose-up pitch excursion after touchdown was driven by the combination of the aft centre of gravity, the high landing pitch attitude, and the negative thrust generated when the power levers were moved toward GROUND IDLE.
- Elevator effectiveness was significantly reduced due to the low airspeed and the disruption of airflow caused by the negative thrust.
- The use of nose-up trim during the flare phase contributed to the high touchdown attitude.