Description

On 1 January 2007, the crew of a ATR 42-500 carried out successive night approaches into Seinajoki Finland including three with Terrain Avoidance and Warning System (TAWS) warnings, one near stall, and one near loss of control, all attributed to poor flight crew performance including use of the wrong barometirc sub scale setting.

Summary

This is an extract from the Investigation Report published by the Accident Investigation Board Finland:

"An incident occurred in Seinäjoki aerodrome airspace on 1 January 2007 from 17:50-18:30 local time. The incident involved a Finncomm Airlines ATR-42 airliner, call sign WBA205S. The aircraft made several unsuccessful instrument approach attempts to Seinäjoki. Onboard warning systems generated several warnings during approaches. In the end, the aircraft was flown to Vaasa, the alternate aerodrome.

The aircraft departed Helsinki at 17:15 and flew to Seinäjoki at FL 200. The first officer was the Pilot Flying

Meteorological conditions at Seinäjoki were: cloud base varying between 500 and 1500 ft; light snow; surface wind 120 degrees 10-12 KT, gusting to 18 KT; wind at 3000 ft 160 degrees 30 KT.

…the aircraft passed Seinäjoki outer marker (PSJ) for runway 32 and initiated an NDB approach via locator O for runway 14. On the final approach the aircraft descended too low, resulting in an EGPWS warning. The first officer flew a missed approach profile towards PSJ. Again, the aircraft descended too low during the approach and they received another EGPWS warning.

After the second missed approach procedure, during the turn to the final approach course, their airspeed decreased, the autopilot disengaged and the stick pusher activated. The flight crew assumed an electrical malfunction and climbed to 7000 ft to work out the cause of malfunction. When no such malfunction was detected, they returned to the outer marker and began to descend in the racetrack pattern. For the third time, the aircraft went too low, resulting in yet another EGPWS warning. The first officer then flew a missed approach procedure.

Soon after this the flight crew noticed that the first officer’s altimeter was incorrectly set to 1013.2 hPa. The captain’s altimeter was set to Seinäjoki QNH 978 hPa.

After that they did an ILS approach to runway 32 and a circling manoeuvre to runway 14. While in the circling manoeuvre, they received yet another warning of an erroneous flight configuration. During the turn to the final approach course the aircraft banked approximately 50 degrees resulting in a bank angle warning. During the missed approach procedure the turn continued and finally they flew at a heading of 050 degrees instead of heading 130 degrees towards PSJ. At 18:29 the captain requested and received a clearance to Vaasa, where they landed at 18:50.

Investigation revealed a mistake concerning the selection of the flight crew for this flight. The captain had only logged some 50 hours on the ATR and the first officer had approximately 80 hours on the aircraft. Irrespective of the captain’s 3500 total flying hours, the crew was inexperienced according to company’s policy with this aircraft type.

The approach preparations to Seinäjoki proceeded too slowly causing the crew to rush. The approach checklist was inadequately completed and they forgot to change the altimeter settings from standard air pressure 1013.2 hPa to Seinäjoki QNH 978 hPa. The result was that they flew the entire time 950 feet too low. Therefore, during the NDB approach to runway 14 the aircraft descended to 345 ft (105 m) above Ground Level (AGL), which activated the unsafe terrain clearance warning. The same factors generated the second warning. This time they descended to 425 ft (130 m) AGL. As they continued with the approach, they lost so much airspeed and the angle of attack increased so much that the stall warning activated, the autopilot disengaged and the stick pusher activated. The anti-icing system was on; therefore, the stall warning and the stick pusher activation threshold took place at a higher airspeed and lower angle of attack compared to normal. This time they descended to 1250 ft (385 m) at minimum. Unsafe terrain clearances generated the EGPWS warnings. Too low airspeed and the rapidly increased angle of attack activated the stall warning and the stick pusher.

The first officer’s fatigue and loss of concentration caused the excessive bank angle during the circling approach. The captain should have taken over at this stage. The Cockpit Voice Recorder (CVR) data analysis revealed poor Crew Resource Management (Crew Resource Management), several missing checks, inadequate system knowledge and incomplete following through of approach procedures.

In order to establish the underlying factors of the occurrence, the investigation looked into the airline’s quality system, training system, organization and management as well as their security culture. Shortcomings were discovered in all of the above. The company had not sufficiently prepared for the challenges of the then ongoing business expansion. Nevertheless, the airline took corrective action during the time of the investigation.

The commission issued three recommendations. The incorrect altimeter setting, the flight crew’s limited experience on the aircraft type and insufficient situational awareness were considered the causal factors for the chain of events which triggered the incident. Shortcomings in the airline’s training system, organization, quality system and security culture were regarded as contributing factors."

Related Articles

CFIT

• Controlled Flight Into Terrain (CFIT)
• Altimeter Setting Procedures
• Circling Approach
• GPWS/TAWS

LOC

• Loss of Control,
• Recovery from Unusual Aircraft Attitudes,
• Stall.

Further Reading

For further information see the full Investigation Report by the AIBF (Finland).