Casualties unknown

Icing Encounter Leads to Off-Route Descent (N4108R)

Flagstaff, AZ, US

On November 18, 1994, a Piper PA-32-300 (registration N4108R) operated by Stephen M. Mumford was involved in an aviation accident near Flagstaff, AZ. Investigators recorded the probable cause as: the pilot's intentional flight into known adverse weather conditions, his misjudged evaluation of the weather, and his inexperience in actual instrument flying. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 8 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-07-04Data APIEditorial standards

During an instrument flight, a pilot with a recent instrument rating encountered icing, leading to pitot-static system failure and an opaque windshield. The pilot received an approach clearance but deviated from the airway, with the aircraft later found off-route.

Weather Briefing and Flight Planning

During the pilot's preflight weather briefing, forecast icing conditions were reported near the intended route of flight below 16,000 feet. The briefing also indicated that the route might require flying between two fronts. The pilot filed an instrument flight rules (IFR) clearance for a minimum en route altitude (MEA) of 11,000 feet. Additional information was provided that several inbound aircraft had encountered icing at 9,000 feet.

In-Flight Icing Encounter

After takeoff, 34 minutes into the flight, the pilot reported that ice was accumulating on the aircraft and that the pitot-static system had become iced over. Unable to climb to the MEA of 11,000 feet, the pilot received an approach clearance to a nearby airport. While cruising between 9,200 and 9,700 feet—an altitude well below the MEA—the pilot stated that he was still attempting to climb and was experiencing considerable ice accumulation, resulting in an opaque windshield. The pilot reported his position as 17.9 miles from the airport.

Discovery of Aircraft

In July 1995, the aircraft was located 14.5 miles from the airport at a bearing of 353 degrees. This location was not on any federal airway or route structure associated with the instrument approach procedure. The pilot had received his instrument rating three weeks prior to the accident flight.

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Frequently asked questions

What happened in the 18 Nov 1994 Piper PA-32-300 accident near Flagstaff, AZ?

During an instrument flight, a pilot with a recent instrument rating encountered icing, leading to pitot-static system failure and an opaque windshield. The pilot received an approach clearance but deviated from the airway, with the aircraft later found off-route.

What aircraft was involved and where did it happen?

The accident on 18 Nov 1994 involved a Piper PA-32-300, registration N4108R, operated by Stephen M. Mumford, at Flagstaff, AZ.

What was the probable cause of the accident?

the pilot's intentional flight into known adverse weather conditions, his misjudged evaluation of the weather, and his inexperience in actual instrument flying.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001206X02614. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.