DEN07LA078 · Dassault Aviation Mystere Falcon 900C

Prior to departure, the airplane was fueled with approximately 17,500 pounds (lbs) of fuel, which allowed a landing weight at the destination of greater than 2,000 lbs. under maximum gross landing weight. The pilot "did not use wet runway performance numbers...[and] did note the 135 landing distance requirements as an aid for safety margin; approximately 6,600 feet." During the downwind leg to runway 26, the crew could see the runway. Prior to the final approach fix for the instrument landing system (ILS) approach to runway 26 and approximately 8 miles from the airport, the crew had the runway in sight. The pilot flew the airplane on the glideslope approximately VRef (Final Approach Speed) 128 knots plus 10-15 knots, then below 1,000 feet, VRef plus 10 knots. The crew reported that the airplane touched down approximately 1,500 feet from the approach end of runway 26. The co-pilot reported the airbrake was in the #2 position and they had "good anti-skid indication" after touchdown. The pilot began braking, deployed the thrust reverser, and continued to increase brake pressure. With approximately 2,500 feet of runway remaining, the airplane continued to not decelerate normally, and the pilot knew they did not have enough runway to execute a go-around. With approximately 1,000 feet of runway remaining, the pilot pulled the parking brake to the second detent, and the aircraft slid off the end of the runway into the dirt and muddy terrain. A performance study revealed that the accident flight crossed the runway 26 threshold at 150 knots airspeed (VRef plus 22 knots) and touched down 2,300 feet from the threshold at 141 knots airspeed (VRef plus 13 knots), with a minus 1 foot per second vertical speed. Immediately at touchdown, the spoilers were deployed. Approximately 4 seconds later and 3,260 feet from the threshold (3,740 feet of landing distance remaining), the thrust reverser was fully deployed with engine 2 fan speed (N1) reaching about 100 percent 9 seconds later. The airplane continued to roll down the runway with the thrust reverser deployed and exited the end of the runway at about 65 knots ground speed coming to a stop in the safety area approximately 268 feet from the end of runway 26. The airport featured one ungrooved asphalt runway, Runway 8/26, which was 7,000 feet by 100 feet, and had a 1.25 percent downslope gradient to the west. According to the airport/facilities directory, the airport remarks section notes, "Runway 08-26 slick when wet, airport manager recommends landing uphill on runway 08 when able." The accident airplane's flight manual does not provide any data on runway slope effect on the landing distance, therefore, the distances mentioned above would increase for landing on runway 26 which has a negative (down) 1.25 percent slope. Since 2001, 12 business jet aircraft have experienced a runway overrun on runway 26. All but one of the overruns included "wet" runway conditions. Since the accident, the runway has been grooved and plans are proceeding with a runway improvement project.

Verbatim NTSB analysis and probable cause from the NTSB dataset