Centaurus
11th Mar 2013, 08:32
The Accident report has just been published on an ADC Airlines Boeing 737-200, registration 5N-BFK that crashed with fatal consequences at Abuja, Africa on 29 October 2006
Here is the link: http://www.tsb.gc.ca/eng/rapports-reports/aviation/2011/A11O0031/A11O0031.pdf
It is a 25MB file.
Briefly - the aircraft took off in heavy rain and windshear conditions under an active thunderstorm with tops over 50,000 ft. Another aircraft in front of him elected to not depart until the storm had passed over. A wise decision as it turned out.
Immediately after lift-off, there was an increasing airspeed indication followed by sudden drop in airspeed. In an instinctive attempt to regain lost airspeed, the captain over-reacted by pushing the nose down initially to minus five degrees below the horizon, then four seconds later jerked back to 35 degrees nose up into a full aerodynamic stall, accompanied by compressor stalls on both engines The aircraft rolled over 90 degrees before hitting the ground.
92 passengers and four crew died in the accident.
Investigators revealed the captain undertook simulator training at Sabena Flight Academy in Brussels, Belgium. However, the simulator used for training did not have the same facilities as the actual aircraft. The captain received windshear training but according to the report it was inappropriate as the simulator was not a replica of the actual aircraft. Windshear recognition and recovery was not part of the simulator training the first officer received. Throughout the emergency period (from first windshear warning to ground impact) the responses from the first officer was not in comformity with the windshear recovery procedures.
Investigation Findings included statements that the captain's command upgrade simulator training was performed with only one instructor who also did the checks. The same instructor also conducted the captain's line training. Thus there was no quality assurance double check. There were significant inconsistencies in the first officer's claimed log book hours. The flight simulator training facility available to the airline, though approved by the Regulatory Authority, was inappropriate for windshear training on type because it did not have the capability for simulating windshear encounter. The aircraft was pitched to an attitude that resulted in the temporary disruption of airflow and momentary loss of power to both engines.
The Causal Factor nominated in the investigation was the pilot's decision to take off in known adverse weather conditions and failure to execute the proper windshear recovery procedure resulting in the operation of the aircraft outside the safe flight regime, causing the aircraft to stall very close to the ground from which recovery was not possible.
Boeing conducted an FDR performance analysis which concluded the aircraft could have flown through the windshear successfully if the correct procedures had been used.
The last paragraph says it all. Experience has shown that even with correctly configured flight simulators certified for windshear recovery training, there is a tendency for some instructors to hurry through the sequences involved with windshear recovery training. When first introduced into the initial session, it is common to see pilots grossly over-correcting pitch attitudes in their attempts to keep the airspeed within safe limits and are caught off guard by the stick force changes. It takes getting used to. A sudden increase or decrease in indicated airspeed often triggers a hasty attempt at setting the best attitude and severe over-controlling invariably occurs.
In the case of the accident aircraft this was a classic case sometimes seen in the simulator. That is a harsh control column movement to excessive nose down followed immediately by a very marked pitch up into the 30 degree nose up zone and thereafter oscillation of pitch caused by chasing the flight director needles until the aircraft has left the windshear.
There is sometimes a tendency for instructors to try and get quickly through the windshear recovery lesson so that regulatory boxes can be ticked and the next training sequences started. In fact, most pilots undergoing windshear recovery training need several practice attempts at each specific windshear sequence (on the take off run, rotation and initial climb, short final, go-around etc). This all takes up valuable simulator time and it is probable that the time allotted to windshear recovery training during the simulator period may be only about 15 minutes.
That might be just enough to cover all the scenarios above but leaves precious little time to repeat each exercise until the pilot is truly confident and competent before the box is ticked. if pilots encounter difficulties during these sequences, a good instructor will hop into the seat and demonstrate how it should be done. A picture is worth a thousand words.
Here is the link: http://www.tsb.gc.ca/eng/rapports-reports/aviation/2011/A11O0031/A11O0031.pdf
It is a 25MB file.
Briefly - the aircraft took off in heavy rain and windshear conditions under an active thunderstorm with tops over 50,000 ft. Another aircraft in front of him elected to not depart until the storm had passed over. A wise decision as it turned out.
Immediately after lift-off, there was an increasing airspeed indication followed by sudden drop in airspeed. In an instinctive attempt to regain lost airspeed, the captain over-reacted by pushing the nose down initially to minus five degrees below the horizon, then four seconds later jerked back to 35 degrees nose up into a full aerodynamic stall, accompanied by compressor stalls on both engines The aircraft rolled over 90 degrees before hitting the ground.
92 passengers and four crew died in the accident.
Investigators revealed the captain undertook simulator training at Sabena Flight Academy in Brussels, Belgium. However, the simulator used for training did not have the same facilities as the actual aircraft. The captain received windshear training but according to the report it was inappropriate as the simulator was not a replica of the actual aircraft. Windshear recognition and recovery was not part of the simulator training the first officer received. Throughout the emergency period (from first windshear warning to ground impact) the responses from the first officer was not in comformity with the windshear recovery procedures.
Investigation Findings included statements that the captain's command upgrade simulator training was performed with only one instructor who also did the checks. The same instructor also conducted the captain's line training. Thus there was no quality assurance double check. There were significant inconsistencies in the first officer's claimed log book hours. The flight simulator training facility available to the airline, though approved by the Regulatory Authority, was inappropriate for windshear training on type because it did not have the capability for simulating windshear encounter. The aircraft was pitched to an attitude that resulted in the temporary disruption of airflow and momentary loss of power to both engines.
The Causal Factor nominated in the investigation was the pilot's decision to take off in known adverse weather conditions and failure to execute the proper windshear recovery procedure resulting in the operation of the aircraft outside the safe flight regime, causing the aircraft to stall very close to the ground from which recovery was not possible.
Boeing conducted an FDR performance analysis which concluded the aircraft could have flown through the windshear successfully if the correct procedures had been used.
The last paragraph says it all. Experience has shown that even with correctly configured flight simulators certified for windshear recovery training, there is a tendency for some instructors to hurry through the sequences involved with windshear recovery training. When first introduced into the initial session, it is common to see pilots grossly over-correcting pitch attitudes in their attempts to keep the airspeed within safe limits and are caught off guard by the stick force changes. It takes getting used to. A sudden increase or decrease in indicated airspeed often triggers a hasty attempt at setting the best attitude and severe over-controlling invariably occurs.
In the case of the accident aircraft this was a classic case sometimes seen in the simulator. That is a harsh control column movement to excessive nose down followed immediately by a very marked pitch up into the 30 degree nose up zone and thereafter oscillation of pitch caused by chasing the flight director needles until the aircraft has left the windshear.
There is sometimes a tendency for instructors to try and get quickly through the windshear recovery lesson so that regulatory boxes can be ticked and the next training sequences started. In fact, most pilots undergoing windshear recovery training need several practice attempts at each specific windshear sequence (on the take off run, rotation and initial climb, short final, go-around etc). This all takes up valuable simulator time and it is probable that the time allotted to windshear recovery training during the simulator period may be only about 15 minutes.
That might be just enough to cover all the scenarios above but leaves precious little time to repeat each exercise until the pilot is truly confident and competent before the box is ticked. if pilots encounter difficulties during these sequences, a good instructor will hop into the seat and demonstrate how it should be done. A picture is worth a thousand words.