What happened
On 1 January 2007, a Finncomm Airlines ATR 42–500, registration OH-ATB, performed several unsuccessful approach attempts at Seinäjoki aerodrome. The flight, operating as WBA205S, arrived from Helsinki under conditions of light snow and variable cloud cover.
During the initial NDB approach to runway 14, the aircraft descended too low, triggering an EGPWS warning and forcing a missed approach. While in the holding pattern, a second EGPWS warning occurred. During the subsequent turn to the final approach, the aircraft's airspeed decreased significantly, causing the autopilot to disengage and the stick pusher to activate. The crew, suspecting an electrical malfunction, climbed to 7,000 feet to investigate.
Upon returning to the holding pattern and descending, a third EGPWS warning was triggered. It was then discovered that the first officer's altimeter had been incorrectly set to the standard pressure of 1013.2 hPa, rather than the local QNH of 978 hPa. This error caused the aircraft to fly approximately 950 feet lower than intended. During a subsequent circling maneuver to runway 14, the crew experienced a bank angle warning after the aircraft tilted approximately 50 degrees. The aircraft eventually diverted to Vaasa, where it landed safely.
The investigation
The investigation examined the flight crew's performance, the aircraft's systems, and the airline's operational standards. Investigators analyzed flight recorder data, which revealed that the crew's coordination (CRM) was poor, and several critical checklists were omitted. The investigation also looked into the airline's training, quality management, and organizational structure during a period of rapid expansion.
Findings
- The primary cause of the altitude warnings was a failure to correctly set the altimeter pressure to the local QNH, resulting in a flight path 950 feet below the intended altitude.
- The crew was considered inexperienced according to company policy, with the captain having only 50 hours on the ATR type and the first officer having 80 hours.
- The activation of the stick pusher and stall warnings was caused by a rapid increase in the angle of attack following a sharp decrease in airspeed.
- The crew's lack of familiarity with the aircraft's systems led them to misidentify the cause of the warnings as an electrical malfunction.
- Contributing factors included deficiencies in the airline's training program, inadequate oversight of crew training, and a safety culture that had not kept pace with the company's growth.