Casualties unknown

1988-02-04: Cessna 421A (N517S) — Minuteman Aviation — Helena, MT

Helena, MT, US

On February 4, 1988, a Cessna 421A (registration N517S) operated by Minuteman Aviation was involved in an aviation accident near Helena, MT. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 3 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

During a night ILS approach to Runway 27 in instrument meteorological conditions, the aircraft struck a mountain 12 nautical miles east-southeast of the airport while turning inbound to intercept the localizer. Investigation found the VOR receivers were set to incorrect frequencies and the second receiver's controls were difficult to read.

Accident Overview

An accident occurred during a night instrument landing system (ILS) approach to Runway 27 in instrument meteorological conditions (IMC). The aircraft collided with a mountain located 12 nautical miles east-southeast of the airport while turning inbound to intercept the localizer course.

Investigation Findings

Investigation revealed that one VOR receiver was tuned to the destination ILS frequency, while the second VOR receiver was set to the frequency of an en route VOR station located 51 nautical miles west of the destination airport. The distance measuring equipment (DME), a separate transceiver, was set to the destination DME transmitter. The frequencies of the en route VOR and the destination VOR were 117.1 MHz and 117.7 MHz, respectively.

The outbound course for the ILS approach procedure was 088 degrees. The accident site was located on the 088 radial of the en route VOR.

Cockpit Configuration

At the time of the accident, the pilot in command (PIC) was occupying the right front seat. An experienced pilot who was not current in this aircraft type was occupying the left front seat. The second VOR receiver control head was located in the lower right portion of the instrument panel, a position where the selected frequency was difficult to read.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X25045. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.