4 fatalities

Air Ambulance Aircraft Collides with Ridge During ILS Approach in Casper (N96JP)

Casper-Natrona County, United States of AmericaLanding (descent or approach)

On April 6, 1993, a Mitsubishi MU-2 Marquise (registration N96JP) operated by Casper Air Service was involved in an aviation accident near Casper-Natrona County, United States of America during landing or approach. 4 people were killed. Investigators recorded the probable cause as: Failure of the pilot to maintain proper altitude during the night IFR approach in instrument meteorological conditions (IMC). This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 6 related events involving the same aircraft type or operator are linked below.

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary report: the U.S. National Transportation Safety Board (NTSB) historical archiveUpdated 2026-07-04Data APIEditorial standards

An air ambulance on an ILS approach to Casper, Wyoming, collided with a ridge about 8 miles from the airport, killing all four occupants. The pilot failed to maintain proper altitude during night IFR in IMC.

Accident

An air ambulance (EMS) flight was conducting an ILS approach to runway 08 at Casper, Wyoming. The aircraft was cleared for the approach and radar data showed it tracking and descending normally on the DME arc until it dropped below radar coverage. Subsequently, the aircraft collided with the top of a ridge along the localizer centerline, before reaching the outer marker and about 8 miles from the airport. The crash site elevation was approximately 5,800 feet. The minimum descent altitude before intercepting the ILS glide slope was 7,100 feet, and the crossing altitude at the outer marker was 6,700 feet. All four occupants—a patient, two doctors, and a pilot—were killed.

Investigation

The official investigation determined the probable cause of the accident. The findings stated that the pilot failed to maintain proper altitude during the night instrument flight rules (IFR) approach in instrument meteorological conditions (IMC).

Probable Cause

Failure of the pilot to maintain proper altitude during the night IFR approach in instrument meteorological conditions (IMC).

Frequently asked questions

What happened in the 6 Apr 1993 Mitsubishi MU-2 Marquise accident near Casper-Natrona County, United States of America?

An air ambulance on an ILS approach to Casper, Wyoming, collided with a ridge about 8 miles from the airport, killing all four occupants. The pilot failed to maintain proper altitude during night IFR in IMC.

Were there any fatalities in the 6 Apr 1993 Mitsubishi MU-2 Marquise accident?

The accident was fatal, resulting in 4 fatalities.

What aircraft was involved and where did it happen?

The accident on 6 Apr 1993 involved a Mitsubishi MU-2 Marquise, registration N96JP, operated by Casper Air Service, at Casper-Natrona County, United States of America.

What was the probable cause of the accident?

Failure of the pilot to maintain proper altitude during the night IFR approach in instrument meteorological conditions (IMC).