Overview
Air Manila Flight UM507, a scheduled domestic flight from Manila International Airport to Lapu-Lapu/Mactan International Airport, operated with a flight number of UM507. Before departure, the pilot received a briefing from an Air Manila dispatcher regarding a cold front along the route and an en-route weather forecast valid from 1200 to 2400 hours, which mentioned isolated thunderstorms over Eastern Visayas and generally fair conditions elsewhere. No specific information about thunderstorms on the planned route was provided to the pilot.
Sequence of Events
The flight departed Manila at 1814 hours, climbing to flight level 130 (FL 130) as cleared by air traffic control. The planned route followed Track 5, Amber 4, and Amber 1, with an airspeed of 210 knots and an estimated en-route time of 1 hour 45 minutes. Normal radio communication was maintained throughout. At 1908 hours, the crew reported reaching Romblon at FL 130 and estimated arrival at Mactan at 1954 hours. This was the last transmission from the aircraft.
Approximately 10 minutes later, at around 1918 hours, residents of Ibajay, a coastal town in Aklan, heard a sound resembling an aircraft flying at high altitude in a southeast direction along the coastline. They then heard several loud explosions and saw fireballs falling into the sea. Witnesses described an initial fireball that developed rapidly from a small fire into a large orange-yellow-red ball before extinguishing. Subsequently, smaller fireballs emerged from the larger one; some died out before reaching the sea, while others reached the water and produced large fires. A large object resembling an airplane was seen emerging from thick clouds and falling into the sea, followed by a trail of smaller objects. About one hour later, two bodies were recovered approximately 2 kilometers offshore of Bo. Colong-Colong, Ibajay, Aklan.
Investigation Findings
The investigation determined that the aircraft disintegrated at high altitude with considerable speed. None of the recovered aircraft parts showed evidence of fatigue, explosion due to combustible gas mixtures, or concentrated explosives such as dynamite. The last position report over Romblon at 1908 hours indicated no operating difficulties. Thunderstorm cells were present over the area near the time of the accident, and two other flights deviated to avoid the area. The crash location was approximately 10 nautical miles to the right of the assigned airway. Only two bodies were recovered; the other occupants and the majority of the wreckage could not be located due to the depth of the sea in the general area.
Probable Cause
The Board determined that the probable cause of the accident was an in-flight structural failure due to air loads exceeding the design strength, while flying in a thunderstorm cell.