- NEWSDAY.CO.TT - A la Une - 17/Jul 09:02

The mystery of Air India Flight 171 crash deepens

On July 10, the Indian Air Accident Investigation Bureau (AAIB) issued a preliminary report on the crash of Air India flight AI 171 to the Indian Minister of Civil Aviation. This report will be submitted to the ICAO within 30 days from the date of the accident as required by ICAO Annexe 13 – Accident Investigation. On June 12, a Boeing 787-8 Dreamliner aircraft took off from Runway 23 at Sardar Vallabhbhai Patel International Airport, Ahmedabad, on a flight to Gatwick Airport, London. After 32 seconds in flight, the aircraft impacted the BJ Medical College hostel, which is 0.9 nautical miles from the departure end of Runway 23. The crash killed 241 people onboard, with one survivor and 19 people on the ground. The investigation led by AAIB includes an accredited representative from the US National Transportation Safety Board and technical advisers from Boeing, General Electric and the US Federal Aviation Administration to assist in the investigation. A team of officials from the UK AAIB are also assisting with the investigation. [caption id="attachment_1167017" align="alignnone" width="1024"] Boeing 787 engine fuel switches.Photo courtesy Metro Vaartha -[/caption] According to the preliminary report, the enhanced airborne flight recorders (EAFR) indicated that the aircraft lifted off at 8.08.39 UTC. The aircraft achieved the maximum recorded airspeed of 180 knots at about 08.08.42 UTC. Immediately thereafter, the Engine One and Engine Two fuel cutoff switches transitioned from the "run" to the "cutoff" position, one after another, with a time gap of one second. Both engine rotational speeds began to decrease from their take-off values as the fuel supply to the engines was cut off. This caused the automatic deployment of the ram air turbine (RAT) to supply hydraulic power. The impact witness marks on the building and the aircraft seem to indicate that the pilot flying, even with decaying airspeed, tried to keep the aircraft in a nose-up attitude. On the day of the accident, the 32-year-old co-pilot was flying the Dreamliner while the 56-year-old captain, as the pilot not flying, was monitoring and supporting the flight through communication with air traffic control and aircraft systems monitoring. In the replay of the cockpit voice recorder (CVR), one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so. The EAFR readout showed that the Engine One fuel cutoff switch transitioned from "cutoff" to "run" at about 08.08.52 UTC. [caption id="attachment_1167018" align="alignnone" width="878"] -[/caption] At 08.08.56 UTC, the Engine Two fuel cutoff switch also transitioned from "cutoff" to "run". When fuel control switches are moved from cutoff to run while the aircraft is inflight, each engine's full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction. The preliminary report stated that the EGT was observed to be rising for both engines, indicating relight. Engine One’s core deceleration stopped, reversed and started to progress to recovery. Engine Two was able to relight but could not arrest core speed deceleration and repeatedly reintroduced fuel to increase core speed acceleration and recovery. The EAFR recording stopped at 08.09.11 UTC, just after the point of impact with the ground. There are several issues to this baffling accident. Firstly, based on the CVR playback, it is easy to identify which one of the pilots asked the other, "Why did he cutoff?" It is very unlikely that the pilot asking this question may have been the one who put both engine fuel switches into the cutoff position. Likewise, the CVR playback can identify which of the two pilots made the "mayday" distress call. Secondly, the fuel switches are ergonomically designed to prevent accidental movement from "run" to "cutoff" or vice versa. For example, to activate a switch from run to cutoff, it must be pulled up from a detent to unlock from the "run" position and placed to the "cutoff" detent position. Therefore, it is highly improbable for the two engine switches to move without a deliberate intervention. Thirdly, both pilots would be fully aware of the catastrophic consequences of the loss of thrust on both engines at very low altitudes and low airspeeds. This is where the mystery deepens. At this critical phase of flight, the co-pilot who was seated on the right-hand seat in the cockpit was flying the aircraft and would normally have both hands on the control column. The captain who was not flying was seated on the left-hand seat with free hands and closer to the Engine One cutoff switch. Both engines' fuel switches transitioned from "run" to "cutoff" and back to "run" in the same sequence. According to the preliminary report, a number of subject matter experts (SMEs) – experienced pilots, engineers, aviation medicine specialists, aviation psychologists and flight recorder specialists – have been taken on board to assist the investigation in the area of their domain expertise. The inclusion of an aviation medicine specialist and an aviation psychologist seems to suggest that the private and professional lives of both pilots will be further probed by investigators, including very detailed background checks. All simulator check assessments reports, training records, medical records, flying experience, time on type, rest times for the last 28 days prior and the initial employment psychometric tests will be intensely analysed. Friends, relatives, relevant Air India flight operations personnel and other pilots, particularly those who flew with the flight crew of AI 171, would be meticulously interviewed. This may reveal any latent emotional and psychological trauma that could have affected the AI 171 pilots' behaviours. The preliminary report only contains factual information. After detailed analysis, the final report, when issued, will indicate the most probable cause(s). On July 23, 1983, a Boeing 767-233 operating Air Canada scheduled domestic Flight 143 between Montreal and Edmonton ran out of fuel midway through the flight at a cruise altitude of 41,000 feet. The pilots successfully glided the aircraft without any engine thrust whatsoever and made an emergency landing at a former Royal Canadian Air Force base in Gimli, Manitoba. There were no serious injuries to the 61 passengers and eight crew members on board or to people on the ground. The aircraft sustained only minor damage and was repaired and returned to service until its retirement in 2008. The post The mystery of Air India Flight 171 crash deepens appeared first on Trinidad and Tobago Newsday.