Event Description
During the landing, the airline transport pilot applied the brakes after touchdown on a 4,422-ft-long runway. He perceived that the brakes were not operating and continued pumping them. The pilot considered performing a go-around but determined that there was insufficient remaining runway to do so. The airplane subsequently continued off the end of the runway, impacted a berm, and came to rest upright, resulting in substantial damage to the right wing.
Examination and Data
Postaccident examination of the airplane revealed that brake pressure was obtained on both sets of brake pedals when depressed, and there was no bleed down or reduction in pedal firmness when the brakes were pumped several times. Examination found no evidence of any preimpact anomalies with the brake system that would have precluded normal operation. The pilot indicated that he was not aware of and was not trained on the use of the ALL INTERRUPT button, which is listed as a step in the Emergency Procedures section of the airplane flight manual and is used to disable the anti-skid brake system functions and restore normal braking when the brakes are ineffective. Thus, the pilot did not follow proper checklist procedures.
Data downloaded from the airplane's diagnostic storage unit (DSU) showed that the airplane touched down 1,280 ft beyond the runway threshold, leaving 2,408 ft of runway remaining (the runway had a displaced threshold of 734 ft). The airplane traveled 2,600 ft before coming to rest about 200 ft past the runway end. The touchdown speed was about 91 knots. Comparison with DSU data from previous flights indicated that the calculated deceleration rate during the accident landing was indicative of braking performance as well as or better than the previous landings. Estimated landing distance calculations revealed that the airplane required about 3,063 ft when crossing the threshold at 50 ft above ground level. The target touchdown speed was 76 knots; however, the airplane touched down with only 2,408 ft of remaining runway at a speed higher than the target, resulting in the runway overrun.
Probable Cause
The pilot's failure to attain the proper touchdown point and exceedance of the target touchdown speed, which resulted in a runway overrun.