AVIATION/ AAIB REPORTS ON GHANA FL101

The UK Air Accident Investigation Branch, AAIB, have released their final report into a serious incident involving a GHANA INTERNATIONAL AIRLINES Boeing 757 at Accra, Ghana, on January 28, 2009. On that date, Flight 101 was on International Service from Accra to London Heathrow, with 96 passengers and 9 crew members onboard. The AAIB report states that early in the takeoff roll, the crew discovered they had a blocked pitot tube, which was causing an airspeed discrepancy. According to the report, the Captain decided to continue to takeoff, and deal with the problem while airborne. While climbing thru 18000 feet, the crew selected the left Air Data switch to ALTN, believing this isolated the left Air Data Computer (ADC) from the Autopilot & Flight Director System (AFDS). While climbing thru 36000 feet, the VNAV mode became active and the Flight Management Computer’s (FMCs), which uses the left ADC as their input of aircraft speed, sensed an overspeed condition and provided a pitch-up command to slow the aircraft. The Co-Pilot was concerned about the aircraft’s behaviour and, after several verbal prompts to the Captain, pushed the control column forward. The Captain, uncertain as to what was failing, believed that a stick-pusher had activated. He disengaged the automatics and lowered the aircraft’s nose, then handed over control to the Co-Pilot. The Captain then declared MAYDAY, and requested immediate return to Accra. As the 757 descended towards Accra, the situation was improving, thus the Captain changed the MAYDAY declaration to PAN PAN PAN. Flight 101 went on to land at Accra without incident, with Emergency Services on standby. The post flight inspection revealed the remains of a beetle-like creature in the left pitot system, which was the cause of the blocked pitot tube. The AAIB noted that there have been 2 fatal crashes due to blocked pitot tubes. A BIRGENAIR Boeing 757 crashed off the coast of Puerto Plata, Dominican Republic, on February 6, 1996, killing all 189 passengers and crew onboard. The cause of that crash was traced to insects blocking the left pitot tube. In addition, an AEROPERU Boeing 757 crashed off the coast of Peru on October 2, 1996, killing all 70 passengers and crew onboard. That accident was caused by tape over the pitot tubes. Ground staff had failed to removed the tape after the aircraft had undergone routine inspection. The full AAIB report on the GHANA Flight 101 can be found on the AAIB website.