Individually Owned: 150,657
Corporate Owned: 137,281
Kalispell City Airport
Aircraft Accident/Incident Report
Big Fork, Montana 59911
Thursday, April 25, 2013 10:16 MDT
NTSB Narrative Summary Released at Completion of Accident
The pilot reported that, while conducting a reconnaissance orbit over mountainous terrain, he crossed over a ridgeline and then lost directional control of the helicopter. He applied full left pedal and lowered the nose and collective in an attempt to regain control. The helicopter subsequently impacted the uneven snow-covered terrain and rolled onto its right side.
Postaccident examination of the airframe and engine revealed no evidence of mechanical malfunction or failures that would have precluded normal operation. A weather study for the area around the accident site revealed that the temperature profile and windy environment supported strong up/downdrafts with the potential for mountain wave formation near the altitude at which the flight was maneuvering. It is likely that the pilot was unable to maintain control of the helicopter as a result of a loss of tail rotor effectiveness while operating in the high-altitude environment and in an area with strong up/downdrafts and possible mountain wave activity.
NTSB Probable Cause Narrative
The pilot’s failure to maintain helicopter control while maneuvering over mountainous terrain in strong up/downdrafts and possible mountain wave activity, which resulted in a loss of tail rotor effectiveness.
Event Information
| Type of Event | Accident |
| Event Date | 4/25/2013 |
| Event Day of the Week | Thursday |
| Time of Event | 1016 |
| Event Time Zone | Mountain Daylight Time |
| Event City | Big Fork |
| Event State | MONTANA |
| Event Country | -- |
| Zipcode of the event site | 59911 |
| Event Date Year | 2013 |
| Event Date Month | 4 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 480911N |
| Event Location Longitude | 1135526W |
| Event Location Airport | KALISPELL CITY |
| Event Location Nearest Airport ID | S27 |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 15 |
| Degrees magnetic from airport | 96 |
| Airport Elevation | 2932 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 955 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 305 |
| Weather Observation Facility ID | GPI |
| Elevation of weather observation facility | 2977 |
| Distance of event from weather observation facility (units?) | 18 |
| Time Zone of the weather observation | MDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | -- |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 11 |
| Dew Point at event time (in degress fahrenheit) | -1 |
| Wind Direction (degrees magnetic) | 170 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 9 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.89 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | METAR KGPI 251555Z 17009KT 10SM CLR 11/M01 A2989 R |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 3 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 32788 |
| NTSB Notification Source | FAA NWM Operations Center |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Jun 19 2014 11:14AM |
| User who most recently changed record | stam |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N937GR |
| NTSB Number | WPR13TA205 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Public Use |
| Type of Flight Plan filed | Company VFR |
| Flight plan Was Activated? | Yes |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BELL |
| Aircraft Model | BHT407 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 53282 |
| Certified Max Gross Weight | 5000 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | 2 |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 7 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | Apr 10 2013 12:00AM |
| Airframe hours since last inspection | 6 |
| Airframe Hours | 1308 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | Unknown |
| Aircraft Owner Name | Two Bear Management LLC |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Kalispell |
| Aircraft Owner State | MT |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 59901 |
| Operator is an individual? | No |
| Operator Name | Flathead County Sheriff's Office |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | -- |
| Operator City | Kalispell |
| Operator State | MT |
| Operator Country | USA |
| Operator Zip code | 59901 |
| Operator Code | -- |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| 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) | -- |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | S27 |
| Departure City | Kalispell |
| Departure State | MT |
| Departure Country | USA |
| Departure Time | 945 |
| Departure Time Zone | MDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | S27 |
| Destination City | Kalispell |
| Destination State | MT |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jun 19 2014 11:14AM |
| User who most recently changed record | stam |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |