JammedStab
27th Feb 2012, 01:57
http://i1091.photobucket.com/albums/i399/54H60/acc.png
Th underlined info is from Boeing which adds a bit to the probable cause listed at the bottom of this post.
Sahara India 737-200 crash Mar 08, 1994
Sahara India Airlines Boeing 737 VT-SIA was engaged in a training flight with an instructor and 3 trainee pilots. Five circuits and landings were completed uneventfully and during the sixth touch-and-go exercise, after the take off from runway 28, the aircraft made a left turn and crashed at the International Terminal Apron. The wreckage of aircraft hit an Aeroflot Ilyushin 86 aircraft parked on Bay No. 45 as a result of which it also caught fire. Two Aeroflot employees, a Russian ground engineer and an airport worker were killed on the ground.
The aircraft was a 737-200ADV crashed during a training flight at Palam Airport near Delhi, India. The accident occurred following a touch-and-go landing at the airport. It was the instructor’s first time as an instructor pilot, the training pilot’s first time piloting a 737, and the airline’s first attempt to do its own training.
The aircraft was equipped with a DFDR that recorded the following parameters of interest: roll angle, pitch angle, heading, normal load factor, longitudinal acceleration, column position, engine pressure ratio, airspeed, and altitude. The heading parameter is measured by a single-axis gyro that is subject to known errors when large bank and pitch angles are encountered.
The pilot in training was conducting a touch-and-go manoeuvre, which is commonly used during training to minimize flight time. Even though the instructor pilot had not briefed his trainee pilot that an engine-out exercise would be conducted, the instructor pilot apparently decided to introduce a simulated engine failure during the takeoff following the touch-and-go. As the aircraft rotated, the DFDR indicated that engine thrust was slowly reduced on the left engine.
This reduction was halted momentarily after liftoff—while the instructor pilot retracted the landing gear after positive rate of climb was achieved—then continued until idle thrust levels were reached. As thrust was reduced, the aircraft rolled left about 8 degrees and then returned to wings level. It then rolled sharply to the left to a maximum roll angle of 100 degrees The bank angle was reduced to 60 degrees to the left before again rolling off to 80 degrees left at impact. Pitch angle was 20 degrees nose down at the time.
The diagram presents the results of a simulator study showing that wheel and some rudder were
used to return the aircraft to wings level during the simulated engine failure. At about this time,
the instructor pilot called out “rudder, rudder, rudder.” The simulator evaluation showed that
the rudder moved sharply to the left, which is the wrong direction to correct for a left engine
failure. This caused the aircraft to roll rapidly to the left, even though the simulator evaluation
showed that full right wheel was applied. The lateral control system was not able to overcome
the roll due to sideslip, which was being generated by both the rudder and the thrust asymmetry.
As the manoeuvre progressed, the captain called out “leave, leave, leave,” and the simulation indicates that the rudder input disappeared. This stopped the roll rate to the left, but it was too late to recover the aircraft from the large bank angle and nose-down pitch angle that had already developed.
The following summarizes pertinent information obtained from the simulator analysis:
1. The rudder was operational during the simulated engine failure.
2. The rudder was operational during the final seconds of the Sahara accident .
3. Wheel alone was not sufficient to reverse the rapid roll to the left; only the removal of the left rudder could have resulted in the bank angle time history recorded on the DFDR.
PROBABLE CAUSE: "The accident occurred due to application of wrong rudder by trainee pilot during engine failure exercise. Capt. did not guard/block the rudder control and give clear commands as Instructor so as to obviate the application of wrong rudder control by the trainee pilot".
Th underlined info is from Boeing which adds a bit to the probable cause listed at the bottom of this post.
Sahara India 737-200 crash Mar 08, 1994
Sahara India Airlines Boeing 737 VT-SIA was engaged in a training flight with an instructor and 3 trainee pilots. Five circuits and landings were completed uneventfully and during the sixth touch-and-go exercise, after the take off from runway 28, the aircraft made a left turn and crashed at the International Terminal Apron. The wreckage of aircraft hit an Aeroflot Ilyushin 86 aircraft parked on Bay No. 45 as a result of which it also caught fire. Two Aeroflot employees, a Russian ground engineer and an airport worker were killed on the ground.
The aircraft was a 737-200ADV crashed during a training flight at Palam Airport near Delhi, India. The accident occurred following a touch-and-go landing at the airport. It was the instructor’s first time as an instructor pilot, the training pilot’s first time piloting a 737, and the airline’s first attempt to do its own training.
The aircraft was equipped with a DFDR that recorded the following parameters of interest: roll angle, pitch angle, heading, normal load factor, longitudinal acceleration, column position, engine pressure ratio, airspeed, and altitude. The heading parameter is measured by a single-axis gyro that is subject to known errors when large bank and pitch angles are encountered.
The pilot in training was conducting a touch-and-go manoeuvre, which is commonly used during training to minimize flight time. Even though the instructor pilot had not briefed his trainee pilot that an engine-out exercise would be conducted, the instructor pilot apparently decided to introduce a simulated engine failure during the takeoff following the touch-and-go. As the aircraft rotated, the DFDR indicated that engine thrust was slowly reduced on the left engine.
This reduction was halted momentarily after liftoff—while the instructor pilot retracted the landing gear after positive rate of climb was achieved—then continued until idle thrust levels were reached. As thrust was reduced, the aircraft rolled left about 8 degrees and then returned to wings level. It then rolled sharply to the left to a maximum roll angle of 100 degrees The bank angle was reduced to 60 degrees to the left before again rolling off to 80 degrees left at impact. Pitch angle was 20 degrees nose down at the time.
The diagram presents the results of a simulator study showing that wheel and some rudder were
used to return the aircraft to wings level during the simulated engine failure. At about this time,
the instructor pilot called out “rudder, rudder, rudder.” The simulator evaluation showed that
the rudder moved sharply to the left, which is the wrong direction to correct for a left engine
failure. This caused the aircraft to roll rapidly to the left, even though the simulator evaluation
showed that full right wheel was applied. The lateral control system was not able to overcome
the roll due to sideslip, which was being generated by both the rudder and the thrust asymmetry.
As the manoeuvre progressed, the captain called out “leave, leave, leave,” and the simulation indicates that the rudder input disappeared. This stopped the roll rate to the left, but it was too late to recover the aircraft from the large bank angle and nose-down pitch angle that had already developed.
The following summarizes pertinent information obtained from the simulator analysis:
1. The rudder was operational during the simulated engine failure.
2. The rudder was operational during the final seconds of the Sahara accident .
3. Wheel alone was not sufficient to reverse the rapid roll to the left; only the removal of the left rudder could have resulted in the bank angle time history recorded on the DFDR.
PROBABLE CAUSE: "The accident occurred due to application of wrong rudder by trainee pilot during engine failure exercise. Capt. did not guard/block the rudder control and give clear commands as Instructor so as to obviate the application of wrong rudder control by the trainee pilot".