On 26 March 2008, a Ukraine International Airlines’ Boeing 737-300 operating a scheduled passenger flight from Kiev to Helsinki descended below its ATC cleared altitude and MSA in day IMC whilst being vectored to the ILS and camer close to a telecommunications mast before ATC noticed the error and ordered it to immediately return to the cleared altiude. There were no abupt manoeuvres and none of the 29 occupants were injured.
An Investigation was carried out by the Accident Investigation Board Finland (AIBF). FDR and CVR data was not available but QAR data was and this proved invaluable to the Investigation. This data showed that the aircraft had descended to an altitude of 1400-1500 feet in the vicinity of the 1227 feet high mast before ATC instructed a climb. It was noted that the First Officer had been PF.
It was concluded that "the incident was caused by an incorrect altimeter pressure setting indicating an altitude which was more than 1000 ft erroneous. The wrong altimeter setting was the result of the pilots deviating from their SOPs (SOP). The detection of the incident was delayed by the facts that the Terrain Awareness and Warning System (EGPWS) did not warn of the telecommunications mast and that the MSAW (MSAW) feature in use at Helsinki Air Traffic Control is not utilised for alerting infringements of the minimum safe altitude. Furthermore, investigation revealed that, in violation of airline regulations, the pilots did not report the incident to the aviation authorities or to the airline. The air traffic controller did report the occurrence, albeit simply as an incident. However, by definition, it was a serious incident."
In respect of Probable Cause, the Investigation found that: "The serious incident was caused when the aircraft descended below its ATC clearance altitude, creating the risk of collision with a telecommunications mast ahead of its track. The cause of breaking the clearance altitude was an erroneous altimeter setting. Contributing factors included inadequacies in Crew Resource Management and the fact that the pilots deviated from Standard Operating Procedures."
The following Safety Recommendations were made as a result of the Investigation:
- that the airline ensure that their pilots possess the required information and skills for proper Crew Resource Management, as required by the safe conduct of aviation and compliance with airline operations manuals.
- that Finavia incorporate a Minimum Safe Altitude Warning (MSAW) feature for the Helsinki Terminal Control Area in its next radar software update. "
Altimeter Setting Procedures