21st of March 1968
A Boeing 727-22QC was scheduled to operate a series of domestic cargo flights in the USA, on this day in aviation history in 1968. After a smooth flight from Newark (New Jersey) to O'Hare Chicago (Illinois) the aircraft was being readied for its next leg to San Francisco (California). A new crew came on board the aircraft for the next leg.
With a scheduled take-off weight close to the Maximum Take-Off Weight for the aircraft, the first officer reviewed take-off performance figures for several runways with different flap settings (5º and 15º) and having engine anti-ice off or on. Although a take-off with the flaps at 15º came out as the best option, the captain decided on a take-off with 5º flaps, in his opinion, this gave the best performance.
At 03.39 the aircraft started to taxi towards the departure runway 9R and the crew completed the necessary checklists. Flaps were selected, and after a slight delay, due to a failure indication of the #1 engine anti-ice valve, the aircraft continue towards runway 9R. The pre-takeoff checklist was completed and at 03.51 the take-off clearance was received and a rolling take-off was initiated. Once the initial thrust setting of 1.4 EPR was achieved on all three engines, take-off thrust was set to the take-off EPR of 1.98. During the take-off roll the take-off warning horn sounded. This warning will sound when the #3 engine throttle is above 65% and;
The aircraft is on the ground
Speedbrake lever is not in 0º detent
FLaps are not in take-off range (5º - 25º)
Stab trim is outside the green band ( 1 to 9.5 units nose up)
APU exhaust door is not closed
Click on the picture above to hear the warning sound that the crew heard on this day 1968.
The only way to silence the warning is to correct the condition that causes the warning or when the nose gear is weight off wheels. During the takeoff roll, the crew checked the different items and did not spot anything abnormal, although they indicated that lighting caused some issues in seeing some settings and indications.
Shortly before Vr (Rotation Speed) the take-off warning horn was silenced, making the crew believe the reason for the warning was no longer present. The aircraft was rotated (the captain later stated the force required was abnormally light) and immediately the stick shaker activated, warning the crew they were close to stalling. The captain lowered the nose and shoved the throttles forward, as the aircraft was not climbing or accelerating the throttles were closed and the aircraft settled back on the runway (righthand side of the centerline. Using the brakes and reversers the aircraft was slowed down, until it left the runway, hit a ditch and came to an abrupt halt.
The crew evacuated the aircraft, and all three were hospitalised for various injuries. The aircraft was destroyed by impact forces and the ensuing ground fire.
The accident was investigated by the NTSB and the flaps were found at the 2º setting, outside the take-off range. They concluded in their report (available by clicking here) that the probable cause was;
"The failure of the crew to abort the takeoff after being warned of an unsafe takeoff condition."