Beech C99 accident near Butte, Montana, March 18, 2006
On March 18, 2006 at about 9:55 pm local time, a Beech C99, registered N54RP, was substantially damaged in an accident near Butte, Montana (Bert Mooney airport). It was flown under charter and air-taxi rules (Part 135). 2 people were killed. The weather was instrument conditions (cloud, fog or low visibility).
The NTSB's probable cause their words, unchanged
The second pilot's failure to follow the published instrument approach procedure and the captain/PIC's inadequate supervision. Snow and mountain obscuration were factors.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 18, 2006 · about 9:55 pm local time
- Place
- Butte, Montana · Bert Mooney · map
- Type
- Accident
- Injuries
- 2 people were killed.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft
- Beech C99 · all C99s on the register
- Registration
- N54RP · no longer on the register · serial U-218
- Damage
- Substantial damage
- Flight
- Flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
The cargo flight collided with mountainous terrain in controlled flight while executing an instrument approach procedure. Two pilots were aboard; the company's training and check captain/pilot-in-command in the right seat, and a newly hired commercial pilot in left seat, who was in training for captain The flight had been cleared for the VOR or GPS-B approach via the 7 DME arc. According to the approach plate, the transition to the approach is via a DME arc at 9,000 feet with no procedure turn. The flight is to track inbound on the 127 degree radial, descending down to, but no lower than, 7,700 feet to the initial approach fix (IAF). After crossing the IAF, the flight is to turn to 097 degrees for 10 nautical miles and descend to 6,900 feet. The remainder of the 1.5 nautical miles to the runway is to be flown under visual conditions. Documentation of the accident site indicated that the aircraft collided with trees and subsequently the mountainous terrain on a heading of approximately 127 degrees and about 6,900 feet mean sea level. The initial impact point was located approximately nine nautical miles on a magnetic bearing of 130 degrees from the IAF. Documentation of the horizontal situation indicator (HSI) on the left side instrument panel indicated that the course arrow was positioned to approximately 127 degrees, the inbound heading to the IAF. The co-pilot (right side) course arrow was positioned to 115 degrees. The location of the wreckage and the 127 degree heading on the HSI indicate that the pilots failed to follow the approach procedure and turn to a heading of 097 degrees after crossing the IAF. Instrument meteorological conditions were reported in the area consisting of icing conditions, heavy snow fall, with poor visibility and mountain obscuration. No pre-impact mechanical malfunctions or failures were identified.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 5,219 hours in all; 2,616 in this make and model; 237 in the last 90 days; 88 in the last 30 days; 5,109 as pilot in command; 950 on instruments
- Last flight review: October 1, 2005
- Medical certificate: Class 2
- Seat: rgt
- Injury: fatal
Other crew
- Injury: fatal
The aircraft
- Airframe total time: 22,169 hours
- Last inspection: approved inspection programme, February 1, 2006; 35 hours since
- Maximum gross weight: 11,300 lb
- Seats: 2
- Landing gear: retractable
- Engine: Pratt & Whitney PT6A-36 (turboprop); 0 hours total
- Fire on the ground
The flight
- Departed from: HLN Helena MT at 9:35 pm
- Destination: BTM Butte MT
- Flight plan: IFR
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 360° at 8 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 6,000 ft
- Temperature: 36°F (2°C), dew point 30°F (-1°C)
- Altimeter: 29.71 inHg
- Observation at 9:53 pm from BTM, 6 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.