Incident Overview
On 29 December 2016, a Boeing 737-400 aircraft, registration YR-BAR, operated by Blue Air - Airline Management Solutions, was scheduled for a commercial passenger flight from Bucharest Henri Coandă International Airport (LROP) to Paris Beauvais Tillé Airport (LFOB). The flight number was 0B105 with call sign BMS5MG.
Flight Phase and Warning
After departure, while climbing from flight level 320 to flight level 340, the cabin altitude warning activated. Consequently, the passenger oxygen masks deployed automatically in the cabin.
Crew Actions
The flight crew immediately applied the emergency descent procedure, donned their oxygen masks, and decided to return to Bucharest Otopeni Airport. The aircraft landed safely without any reported casualties.
Aircraft and Operator
The aircraft was a Boeing 737-400, serial number 25371, built in 1992. It was registered in Romania and equipped with two turbofan engines. The operator, Blue Air, is a Romanian airline conducting commercial air transport operations. The flight was scheduled and international, operating under instrument flight rules (IFR).
Location and Environment
The event occurred approximately 12 nautical miles southwest of Sibiu (SIB), at coordinates 46°15'36" North, 024°10'48" East. Weather conditions were visual meteorological conditions (VMC) with daylight. Wind was from 50 degrees at 82 knots.
Investigation
The Romanian Authority for the Investigation of Civil Aviation Accidents and Incidents (AAIB) opened a full investigation under Annex 13. The International Civil Aviation Organization (ICAO), the European Commission, the European Aviation Safety Agency (EASA), and the National Transportation Safety Board (NTSB) of the United States (as the state of design and manufacture) were notified. The NTSB appointed an accredited representative. The investigation team, with assistance from the French Bureau d'Enquêtes et d'Analyses (BEA), downloaded and validated recordings from the cockpit voice recorder (CVR). Analysis of flight parameters is ongoing. As of the preliminary report, the investigation to determine the causes of this serious incident is still in progress.
Traffic and Airspace
The aircraft was under the control of ACC București (Bucharest Area Control Center), sector KONEL, operating in airspace class C. The air traffic services reported no effect on ATM service, with a controller workload rated as high.
Subsequent Actions
No injuries or damage to the aircraft were reported. The incident was classified as a serious incident with category SCF-NP (System/component failure or malfunction [non-powerplant]).