# NTSB SEA00LA183: Beech B99, N99TH, Missoula, MT, September 22, 2000 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 22, 2000, 02:20 local (08:20 UTC) - Place: Missoula, MT - Coordinates: 46.849063, -113.989204 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.8491&lon=-113.9892&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 26, 2003 - Report: Approved by Office Director - NTSB case key (mKey): 50340 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA00LA183 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/50340/pdf - Page: https://openairdocs.org/ntsb/SEA00LA183 ## Probable cause A loss of directional control due to a brake locked as a result of snow and ice contamination. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, landing - landing gear,normal brake system - contamination (cause) - landing gear,normal brake system - locked (cause) - directional control - not possible, pilot in command (cause) - On ground/water collision with object, landing - roll ## Analysis The airplane touched down on the centerline of runway 29. When the pilot applied 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 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 runway at Billings was contaminated with snow and slush. Post-accident inspection of the airplane, by inspectors from the FAA Helena, Montana, Flight Standards District Office, revealed no evidence of system mechanical malfunction that would result in a brake failure. ## Factual narrative On September 22, 2000, about 0220 mountain daylight time (MDT), a Beech B99, N99TH, sustained substantial damage during landing on runway 29, at Missoula International Airport, Missoula, Montana. The airplane was operated by Alpine Air of Provo, Utah, as a domestic cargo flight under the provisions of Title 14, Part CFR 135, when the accident occurred. The commercial pilot, and the airline employee passenger were not injured. Visual meteorological conditions prevailed and an instrument flight plan was filed. The flight originated at Billings, Montana, about 0100 MDT. In a written statement, 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. A skid mark that coincides with the airplanes right main landing gear was noted on the landing runway. The skid mark originated near the runway centerline and continues to the point where the airplane left the runway. 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 (Report attached). ## Aircraft - Registration: [N99TH](https://openairdocs.org/deregistered/N99TH-2011-06-15), registration cancelled 2011-06-15, S/N U-155, built 1974 (OpenAirDocs) - Reported make and model: Beech B99 - Registry model: [Beech B-99](https://openairdocs.org/model/beech-b-99) (registry code 1154004) (OpenAirDocs) - Registry engine: [U/A Canada PT6A-27-28](https://openairdocs.org/engine/u-a-canada-pt6a-27-28) (registry code 61504, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: U-155 - Airframe hours: 36485 - Engines: P&W PT6A-28 680 horsepower turbo prop - Damage: Substantial damage - Flight: Part 135 - Operator: Alpine Air - Registered owner: Clb Leasing - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, September 19, 2000, 136 hours before - Departed: BIL, BILLINGS, MT - Destination: MSO - Flight plan: IFR - Airport: MSO, Missoula International Ai, runway 29, 9,501 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 28; airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 4,696 total, 1,629 in this make and model, 4,507 as pilot in command, 327 in the last 90 days, 116 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 90° at 11 knots - Visibility: 10 statute miles - Lowest ceiling: 8,500 ft broken - Temperature: 37 °F, dew point 19 °F - Altimeter: 30.00 inHg - Observed at: MSO ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20000922015149A](https://openairdocs.org/incident/20000922015149A), Sep 22, 2000: Beech B99, Missoula, MT, No damage. (-23) Pilot stated that the right brake locked up after landing rwy 29 mso. No evidence of equipment failure was found in investigation, but accumulations of… ## Other investigations on N99TH (2) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB CHI07LA050](https://openairdocs.org/ntsb/CHI07LA050), Dec 29, 2006: Beech B-99 (N99TH), Rapid City, SD, substantial damage. Probable cause: The pilot's failure to follow the published instrument approach procedure which contributed to his failure to maintain altitude and clearance from terrain during the instrument approach. A factor was… - [NTSB MIA80IA108](https://openairdocs.org/ntsb/MIA80IA108), Sep 23, 1980: Beech B99 (N99TH), Orlando, FL, incident, minor damage From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.