Individually Owned: 150,657
Corporate Owned: 137,281
Glacier Park Intl Airport
Aircraft Accident/Incident Report
Bigfork, Montana 59911
Saturday, April 11, 1998 2:21 MDT
NTSB Narrative Summary Released at Completion of Accident
The aircraft disappeared from ATC radar immediately after being cleared to descend from 12,000 feet to 10,000 feet. ATC radar data showed the aircraft at 11,900 to 12,000 feet for approximately the last 6 minutes prior to the disappearance, with the last Mode C altitude and discrete transponder code 2402 (at 0221:03) reported as 11,800 feet. The last three returns, 12,000, 11,900, and 11,800, are consistent with the start of a descent from 12,000 feet. Due to construction at the radar antenna site, the area where the aircraft disappeared was blocked from radar coverage. Subsequent attempts by the controller to contact the aircraft were unsuccessful. A 7,000- to 7,500-foot overcast was reported at the destination, along with lower clouds and precipitation. Documentation at the accident site indicated an approximate level flight path from the broken treetops to the area of ground impact into a northwest-facing 60-degree mountain slope at approximately the 5,600-foot level. The wreckage was not located for approximately two months. Post-accident examinations of the aircraft's Bendix/King KEA-130A (United Instruments 5035PB-P57) encoding altimeter revealed needle impressions on the indicator face and pointers consistent with an altitude indication of 12,620 feet. The internal components of the unit were severely damaged and a functional test was not possible. The aircraft was equipped with a copilot's altimeter. Only the faceplate was recovered and examined. One impression on the main faceplate revealed a needle impression by the 100-foot pointer consistent with 560 feet. The position of the 1,000-foot pointer could not be determined. The pilot's 4-day activity history showed that he was returning from a demanding 3-day work assignment, that his recent sleeping schedule was irregular, and that he had been awake about 20 hours at the time of the accident. There was no evidence found of a mechanical failure or malfunction at the time of the accident.
NTSB Probable Cause Narrative
The pilot's failure to maintain terrain clearance for undetermined reasons. Contributing factors were the mountainous terrain, trees, dark night conditions, clouds and pilot fatigue.
Event Information
| Type of Event | Accident |
| Event Date | 4/11/1998 |
| Event Day of the Week | Saturday |
| Time of Event | 221 |
| Event Time Zone | Mountain Daylight Time |
| Event City | BIGFORK |
| Event State | MONTANA |
| Event Country | -- |
| Zipcode of the event site | 59911 |
| Event Date Year | 1998 |
| Event Date Month | 4 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | GLACIER PARK INTL |
| Event Location Nearest Airport ID | FCA |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 24 |
| Degrees magnetic from airport | 109 |
| Airport Elevation | 2972 |
| Weather Briefing Completeness | Full |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 256 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 289 |
| Weather Observation Facility ID | FCA |
| Elevation of weather observation facility | 2972 |
| Distance of event from weather observation facility (units?) | 21 |
| Time Zone of the weather observation | MDT |
| Lighting Conditions | Night/Dark |
| Lowest Ceiling Height | 6000 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Unknown |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 9 |
| Air Temperature at event time (in degrees celsius) | 37 |
| Dew Point at event time (in degress fahrenheit) | 37 |
| Wind Direction (degrees magnetic) | 0 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 0 |
| Wind Velocity Indicator | Calm |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 29 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | 2 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 1876 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Apr 11 1998 12:00AM |
| NTSB Notification Time | 400 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Jan 4 2005 12:15PM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Unknown |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N9247W |
| NTSB Number | SEA98FA101 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | -- |
| Damage | Destroyed |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Piper |
| Aircraft Model | PA-46-350P |
| Aircraft Series Identifier | PA-46-350P |
| Aircraft Serial Number | 4622168 |
| Certified Max Gross Weight | 4300 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 6 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Oct 3 1997 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | -- |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | CMSYSTEMS INC. |
| Aircraft Owner Street Address | 1115 BAYVIEW DR. |
| Aircraft Owner City | POLSON |
| Aircraft Owner State | MT |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 59860 |
| Operator is an individual? | -- |
| Operator Name | |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | |
| Operator City | |
| Operator State | |
| Operator Country | |
| Operator Zip code | |
| Operator Code | |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Business |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | BIS |
| Departure City | BISMARCK |
| Departure State | ND |
| Departure Country | |
| Departure Time | 2358 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | FCA |
| Destination City | KALISPELL |
| Destination State | MT |
| Destination Country | |
| Specific Phase of Flight | Cruise |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jul 25 2001 4:05AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 30 |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |