Incident Overview
On 26 March 2008 at 14:39 UTC, a serious incident occurred in the Helsinki Terminal Control Area, Finland. A Ukraine International Airlines Boeing 737-300 (registration UR-GAQ), while being radar vectored to Helsinki-Vantaa Airport, descended below its air traffic control clearance altitude of 2300 feet. The aircraft reached a minimum altitude of approximately 1400 feet, resulting in an infringement of the required terrain clearance with a telecommunications mast along its flight path.
Investigation Findings
The Accident Investigation Board Finland (AIB) appointed an investigation commission to examine the incident. The investigation determined that the incident was caused by an incorrect altimeter pressure setting, which produced an altitude display error of more than 1000 feet. The erroneous altimeter setting resulted from the flight crew deviating from standard operating procedures. The investigation could not establish an unequivocal reason for the crew's actions.
Detection of the deviation was delayed because the Enhanced Ground Proximity Warning System (EGPWS) did not provide a warning for the telecommunications mast. Additionally, the Minimum Safe Altitude Warning (MSAW) feature in use at Helsinki Air Traffic Control was not configured to alert for infringements of the minimum safe altitude.
Contributing Factors
Contributing factors to the incident included inadequacies in crew resource management and the pilots' deviation from standard operating procedures. The investigation also noted that, contrary to airline regulations, the pilots did not report the incident to the aviation authorities or to the airline. The air traffic controller filed the required safety report, but classified it as an incident rather than a serious incident, which it was by definition.
Safety Recommendations
The investigation commission issued two safety recommendations. First, the airline should ensure that its pilots possess the necessary knowledge and skills for effective crew resource management and adherence to the airline's operations manuals. Second, Finavia should incorporate a Minimum Safe Altitude Warning feature for the Helsinki Terminal Control Area in the next radar software update.