C7/2008L Incident during approach to Oulu aerodrome on 29 August 2008

An incident occurred on the final approach of runway 30 at Oulu aerodrome on 29 August 2008 at 14:04 UTC. A Finnair Airbus A320 airliner on a scheduled flight from Helsinki to Oulu flew below the minimum airspeed required by its state and phase of flight. On 2 October 2008 after a preliminary analysis Accident Investigation Board Finland appointed investigation commission C7/2008L for this incident. Chief Air Accident Investigator Hannu Melaranta was named Investigator-in-Charge, accompanied by Investigator Markus Bergman serving as member of the commission.

The airspeed of the aircraft was too high during its visual approach and, hence, it remained above the approach profile. In order to reduce excessive altitude the pilots flew a circle during the final approach, with the consent of air traffic control. During the circle the aircraft’s angle of attack increased and its airspeed rapidly decreased. The aircraft’s ‘Alpha floor’ protection activated and selected Take Off Go Around thrust for the engines, which achieved sufficient airspeed. After the thrust increase the pilots continued the approach and landed on runway 30. The aircraft was flying at little over 1000 ft AGL at the time of the incident. There were 161 passengers and 6 crew members onboard.

The investigation established that during the occurrence the aircraft and its systems operated as they were designed to and thus prevented the incident from becoming a more serious one. The meteorological and other external conditions at the time of the approach were good and did not directly affect the incident. The pilots did not have any such theoretical shortcomings that could have explained the onset of the incident. The investigators believe that human factors played an elemental part in the incident. No shortcomings in airline regulations were discovered that could have directly contributed to it. Factors similar to those that contributed to this incident had already been identified and the airline had distributed information circulars to its Airbus pilots containing instructions and limitations associated with these kinds of flight operation risk factors. Not all of these instructions and limitations were included in the Flight Manual.

The incident occurred when the aircraft’s airspeed decreased below the minimum speed required by its state of flight as the pilots were commencing a left turn and straightening out from a descent without increasing thrust as required. The situation was the outcome of an improperly timed reduction of airspeed which, in turn, resulted in the aircraft remaining above the appropriate approach profile. Autothrust disengagement as well as the circle on the final approach were unplanned and therefore had not been included in the approach briefing.

The investigation commission issued one safety recommendation. The airline was advised to review the content of Airbus pilot type training and refresher training as well as the scope of flight crew examinations so as to make certain that identified risk factors in flight operations are appropriately taken into account.

The draft investigation report was sent for comments to the Finnish Civil Aviation Authority and the operator. Their comments were partly incorporated into the final investigation report.

C7/2008L Report (pdf, 0.4 Mt)