# NTSB NYC91FA067: MBB BK 117 B-1, N891GM, Sonestown, PA, January 27, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: January 26, 1991, 19:48 local (Jan 27, 1991, 00:48 UTC)
- Place: Sonestown, PA
- Location: 41.3537° N, 76.5541° W: Placed by OpenAirDocs: center of Sonestown, PA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=41.3537&lon=-76.5541&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 4 fatal
- Status: Completed, report April 30, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 36779
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC91FA067
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/36779/pdf
- Page: https://openairdocs.org/ntsb/NYC91FA067

## Probable cause

THE PILOT'S INADEQUATE PREFLIGHT PLANNING TO ASSURE THAT THE INTENDED COURSE AND ALTITUDE PROVIDED ADEQUATE TERRAIN CLEARANCE. CONTRIBUTING FACTOR(S) WAS: THE DARK NIGHT, SNOW AND MOUNTAINOUS TERRAIN.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight collision with terrain/water, cruise - normal
  - preflight planning/preparation - inadequate, pilot in command (cause)
  - light condition - dark night (contributing factor)
  - weather condition - snow (contributing factor)
  - terrain condition - mountainous/hilly (contributing factor)
  - altitude - inadequate, pilot in command (cause)

## Analysis

THE MEDIVAC HELICOPTER WAS RETURNING TO SAYRE AFTER TRANSPORTING A PATIENT TO DANVILLE. RECORDED RADAR DATA AND DATA OBTAINED FROM THE HELICOPTER'S LORAN-C MEMORY INDICATES THAT THE FLIGHT WAS FOLLOWING A DIRECT COURSE FROM THE GEISINGER MEDICAL CENTER AT DANVILLE TO THE ROBERT PACKER HOSPITAL AT SAYRE. THE ACFT'S HSI WAS SET TO DISPLAY LORAN COURSE INFORMATION. THE CLOSEST POINT OF THE COURSE TO THE CREST OF NORTH MOUNTAIN WAS APRX 3/4 MILE TO THE WEST. THE PILOT HAD ADVISED WILLIAMSPORT ATCT TRANSITTING THEIR CONTROL ZONE AT 2,500 FT. IMPACT OCCURRED AT 2,440 FT MSL. THE CREST OF THE RIDGE IS 2,520 FT MSL WITH 40-FT HIGH TREES. A WITNESS WHO LIVES IN A CABIN ON THE MOUNTAIN 200 YARDS FROM THE ACCIDENT SITE STATED THAT IT WAS SNOWING VERY HARD WHEN HE ARRIVED AT THE CABIN AROUND 1930.

## Aircraft

- Registration: [N891GM](https://openairdocs.org/deregistered/N891GM-1991-08-12), registration cancelled 1991-08-12, S/N 7153 (OpenAirDocs)
- Reported make and model: MBB BK 117 B-1
- Registry model: [Messerschmitt Bolkow Blohm BK117 B-1](https://openairdocs.org/model/messerschmitt-bolkow-blohm-bk117-b-1) (registry code 5626033) (OpenAirDocs)
- Category: Helicopter
- Serial number: 7153
- Engines: LYCOMING LTS101-650B-1 650 horsepower turbo shaft
- Damage: Destroyed
- Flight: Other work use, Part 91
- Operator: Keystone Helicopter Corporatio
- Departed: DANVILLE, PA
- Destination: SAYRE, PA
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 35; commercial; instrument ratings: helicopter; medical: class 1, valid medical--no waivers/lim.; seat: right; toxicology performed; flight hours: 3,267 total, 287 in this make and model, 2,666 as pilot in command, 15 in the last 90 days, 8 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Instrument (IMC), Night/dark
- Temperature: -0 °F, dew point -0 °F

## 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 19910126001099A](https://openairdocs.org/incident/19910126001099A), Jan 26, 1991: Bolkms BK117B1, Sonestown, PA, Destroyed, 4 fatal. Flew into trees on a mountainside at night in a snowshower and dense fog. Operations calls for VFR flight only.

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.

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