Israel Aircraft Industries GULFSTREAM 200 N718QS incident near Jackson, Wyoming

Probable cause

The flight crew's inability to stop the airplane during landing roll on a snow- and ice-contaminated runway. Contributing to the runway overrun were the deteriorating runway conditions.

NTSB analysis

The flight crew reported that, prior to the flight, they were initially delayed due to weather and low runway friction values (MU) at their intended destination. (MU values range from 0 and 100, where 0 is the lowest friction value and 100 is the maximum friction value. A MU value of 40 or less is the level at which aircraft braking performance starts to deteriorate and directional control begins to be less responsive.) Dispatch personnel later reported that the conditions had improved and that the crew was released for the flight. While en route, the crew monitored weather and runway conditions at the destination airport and calculated the required landing distances, which they found to be within acceptable limits for the reported MU values of 41, 37, and 36.

About 10 minutes before landing, MU values were reported as 40, 42, and 40, with patchy thin snow over patchy thin packed snow and ice on the runway surface. The flight crew received these MU values, continued their approach to the airport, and landed. During the landing roll, thrust reversers were deployed, and the crew noted that all of the ground and air slat indication lights were green and that the anti-skid system began to pulse; however, the airplane was not slowing down. Despite the application of maximum thrust reverse, there was no effect on slowing the airplane, and it exited the departure end of the 6,300-foot runway and came to rest just beyond the blast pad. The flight crew reported no mechanical malfunctions or failures with the airplane that would have precluded normal operation. About 7 minutes after the runway overrun, MU values were recorded as 34, 33, and 23. As indicated by the MU values reported just prior to landing, and the lower values reported shortly after landing, the landing was made at a time when the runway conditions were deteriorating, and the braking performance was becoming less effective.

Text from the NTSB. Open the NTSB docket for WPR11IA055 for the full record.