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Date:Friday 22 September 2000
Type:Silhouette image of generic BE99 model; specific model in this crash may look slightly different
Beechcraft B99 Airliner
Operator:Alpine Aviation
Registration: N99TH
MSN: U-155
First flight:
Total airframe hrs:36485
Crew:Fatalities: 0 / Occupants: 1
Passengers:Fatalities: 0 / Occupants: 1
Total:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Aircraft fate: Repaired
Location:Missoula-Johnson-Bell Field, MT (MSO) (   United States of America)
Phase: Landing (LDG)
Departure airport:Billings-Logan Field, MT (BIL/KBIL), United States of America
Destination airport:Missoula-Johnson-Bell Field, MT (MSO/KMSO), United States of America
A Beech B99, N99TH, sustained substantial damage during landing on runway 29, at Missoula International Airport, Montana. The commercial pilot, and the airline employee passenger were not injured. Visual meteorological conditions prevailed.
The pilot reported that the airplane touched down on the centerline of runway 29. He stated that when he applied wheel brakes, "the right brake locked up" and the airplane immediately veered to the right. The pilot applied left brake, left rudder and reversed the left propeller, however, the airplane continued to the right. The airplane collided with a taxiway light and runway marker before departing the right side of the runway. The airplane sustained substantial damage to the fuselage.
Post-accident photographs of the airplane, taken on the night of the accident, revealed ice and snow deposits on the cargo pod, right lower engine nacelle, main landing gear strut and right dual brake assembly. The landing runway in Missoula was dry, however, the departure airport at Billings was contaminated with approximately 6 inches of snow and slush.
On September 22, FAA personnel from the Helena, Montana, Flight Standards District Office, inspected the airplane and reported that there was no evidence of system mechanical malfunction that would have resulted in a brake failure.

Probable Cause:

PROBABLE CAUSE: "A loss of directional control due to a brake locked as a result of snow and ice contamination."

Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Duration: 2 years and 6 months
Accident number: SEA00LA183
Download report: Summary report
Language: English

Runway excursion



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This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Billings-Logan Field, MT to Missoula-Johnson-Bell Field, MT as the crow flies is 440 km (275 miles).

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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Global Action Plan for the Prevention of Runway Excursions (GAPPRE): recommendations and guidance material to prevent runway excursions

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