Incident Overview
On November 16, 1976, Texas International Flight 987, a McDonnell Douglas DC-9-14 (registration N9104), was operating as a scheduled passenger flight from Salt Lake City, Utah, to Houston, Texas, with an intermediate stop at Denver, Colorado. The flight departed the gate at Stapleton International Airport, Denver, with 81 passengers and 5 crew members aboard. Weather conditions were clear, with wind from 130° at 7 knots and temperature 40°F.
Takeoff and Warning Activation
At 1726:33, the tower cleared the flight to take runway 8R and hold while two light aircraft departed from a nearby intersection. At 1729:13, Flight 987 was cleared for takeoff, and at 1729:15, the flight reported rolling. The first officer was performing the takeoff. After receiving clearance, he advanced the throttles to 1.4 EPR, released the brakes, and then advanced to takeoff thrust. The captain guarded the throttles until rotation speed (VR). The takeoff roll was described as normal, with the captain calling out speeds: 100 KIAS, 130 KIAS, V1, VR, V2. The cockpit voice recorder confirmed these calls.
During rotation, at approximately 5° pitch, the stall warning stickshaker activated and continued operating. The first officer continued rotating to about 10°, but the aircraft did not lift off despite airspeed exceeding 150 KIAS. The captain observed 152 KIAS and 10° pitch with normal instrument indications. Both pilots believed the aircraft would not become airborne, and they simultaneously decided to reject the takeoff.
Rejected Takeoff and Overrun
The first officer reduced throttles to idle and applied full reverse thrust, while the captain also placed his hand on the throttles. The first officer applied forward yoke pressure to lower the nose, which lowered rapidly. The stickshaker stopped, though neither pilot could recall exactly when. Full reverse thrust and maximum wheel braking were applied, but ground spoilers were not deployed.
The captain estimated 2,500 to 3,000 feet of runway remained at abort initiation, and noted they were in the amber lighted area (starting 2,000 feet from the eastern threshold). The captain steered right to avoid approach light stanchions for runway 26L. The aircraft departed the runway, traveled another 1,050 feet, crossed two drainage ditches, struck approach light stanchions, turned left, and stopped facing north.
Evacuation and Damage
After stopping, the captain ordered the first officer to assist flight attendants with passenger evacuation. The captain secured the cockpit: shut down engines, closed fuel shutoff valves, pulled engine fire handles, discharged fire extinguishing agent, and turned off battery and ignition switches. All 86 occupants evacuated safely. The aircraft was damaged beyond repair.
Probable Cause
The official finding stated that the probable cause was: A malfunction of the stall warning system, for undetermined reasons, which resulted in a false stall warning and an unsuccessful attempt to reject the take-off after the aircraft had accelerated beyond refusal and rotation speed. The decision to reject the take-off, although not consistent with standard operating procedures and training, was reasonable in this instant case, based upon the unusual circumstances in which the crew found themselves, the minimal time available for decision, and the crew's judgment concerning a potentially catastrophic situation.