AVIATION/ REMEMBERING BIRGENAIR FL301

In the last 2 years, there have been several serious incidents involving obstructed Pitot Tubes, the part of the aircraft that measures speed. Although all of the airliners involved landed safely, investigators believe that the Pitot Tubes played an important part in the loss of AIR FRANCE Flight 447 on June 1, 2009, over the Atlantic. Until the wreckage of the Airbus A330 is located, of if it is, there is no way to definately say for sure what their role was in the crash. However, back on October 2, 1996, AEROPERU Flight 603 went down in the Pacific, claiming the lives of all 70 passengers and crew onboard. Investigators determined that the Pitot Tubes had been taped over with masking tape during ground maintenance and that grouind staff failed to remove the tape, prior to the Boeing 757 returning to service. That failure led to the crew receiving false airspeed and altitude readings, which led to the crash. About 8 months earlier, on February 6, 1996, BIRGENAIR Flight 301 went down in the Caribbean Sea, claiming the lives of all 189 passengers and crew onboard. Once again, obstructed Pitot Tubes most likely caused the Boeing 757 to go down.

15 years ago today, Birgenair Flight 301 was on Scheduled International Service from Puerto Plata, Dominican Republic, to Frankfurt, Germany, with 176 passengers and 13 crew members onboard. The passengers were mostly German tourists, returning from their Caribbean vacation. The 757 departed Puerto Plata at 11:42pm. At 80 knots on their takeoff roll, the Captain noted that his air speed indicator (ASI) wasn't working properly. The Co-Pilot's indicator appeared to be working normally. While climbing through 4700 feet, the Captain's ASI read 350 knots, however their real speed was about 220kt). This resulted in an autopilot/autothrottle reaction to increase the pitch-up attitude and a power reduction in order to lower the airspeed. At that time the crew received 'Rudder ratio' and 'Mach airspeed' advisory warnings. Both Pilots became confused the Co-Pilot said that his ASI read 200 knots decreasing while getting an excessive speed-warning, followed by a stick shaker warning. This led the Pilots to believe that both ASIs were unreliable. Realizing they were losing speed and altitude, they disconnected the autopilot and applied full thrust. (It should be noted that the Captain's faulty ASI fed the autopilot, which in response, had already reduced speed close to stall speed). At 11:47:17pm, an aural GPWS warning alarm sounded in the cockpit. 8 seconds later, at 11:47:25, just about 5 minutes after taking off, the aircraft struck the ocean. The Probable Cause of the crash was related to the Pilots failure to recognize that the stick shaker warning was a sign of impending stall and the Pilots failure to execute the necessary procedures to recover. Yet, investigators also believe that the Pilots may not have had a chance to recover as they believe that 1 of the 3 Pitot Tubes was obstructed, which would have caused the cascade of events to begin. The investigation determined that the 757 that crashed, pictured top, had been parked in Puerto Plata for several days prior to the crash. Most reports say it was parked 3 or 4 days, while a few others say it was parked for as many as 25 days. What is not in dispute, is that the aircraft was left uncovered while it was parked. Based on previous incidents at the Airport and native insects, the investigators believe that some kind of insect, probably a type of wasp, built a nest in 1 of the Pitot Tubes and blocking it. The bulk of the wreckage was never recovered from the ocean floor, pictured above, thus investigators were never able to absolutely determine if this was the true cause of the crash. However, based on what took place later that year on the AeroPeru flight, they believe that this was the cause of the crash. That hypothesis has only been re-inforced with the recent spate of incidents.