Date:	Monday 23 September 1985
Time:	10:20
Type:	Beechcraft B99 Airliner
Owner/operator:	Henson Airlines
Registration:	N339HA
MSN:	U-156
Year of manufacture:	1974
Engine model:	Pratt & Whitney Canada PT6A-27
Fatalities:	Fatalities: 14 / Occupants: 14
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	11 km ESE of Staunton-Shenandoah Valley Airport, VA (SHD) -   United States of America
Phase:	Approach
Nature:	Passenger - Scheduled
Departure airport:	Baltimore/Washington International Airport, MD (BWI/KBWI)
Destination airport:	Staunton-Shenandoah Valley Airport, VA (SHD/KSHD)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The crew, cleared for a runway 04 ILS approach, became uncertain of their position. The aircraft struck the southwest face of Hall Mountain at an elevation of 2,400 feet.
Radio equipment installed on the aircraft was non standard (and non FAA approved). The ADF and 2 NAV displays were in an unsuitable location for the first-officer.

PROBABLE CAUSE:
The National Transportation Safety Board determines that the probable cause of this accident was a navigational error by the flightcrew resulting from their use of the incorrect navigational facility and their failure to adequately monitor the flight instruments.
Factors which contributed to the flightcrew's errors were:
- the nonstandardized navigational radio systems installed in the airline's Beech 99 fleet;
- intracockpit corhmunications difficulties associated with high ambient noise levels in the airplane;
- inadequate training of the pilots by the airline;
- the first officer's limited multiengine and instrument flying experience;
- the pilots' limited experience in their positions in the Beech 99;
- and stress-inducing events in the lives of the pilots.
Also contributing to the accident was the inadequate surveillance of the airline by the Federal Aviation Administration which failed to detect the deficiencies which led to the accident.

Lloyds List
NTSB
NTSB Safety Recommendations A-86-98 through -118

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