Alpine Air Piper PA-31-350 accident
Piper PA-31-350 · Accident: gear not extended on approach
From Salt Lake City International Airport (SLC) to an unrecorded destination
Event
- NTSB case
- DEN92LA012
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Charter & commuter
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Instrument Meteorological Cond
Piper PA-31-350
- Aircraft type
- Piper PA-31
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N354AC
- Operator
- Alpine Air
- Onboard fatalities
- Unknown
- Route
- From Salt Lake City International Airport (SLC), Salt Lake City, UTTo not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 135: Air Taxi & Commuter
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Approach
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Gear not extended
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Landing gear, gear indicating system › False indication
- Landing gear, gear switch › Frozen
Approximate · Estimated position: the centre of Denver, CO, the place the record names. Not the accident site.
NTSB narrative
DURING THE APPROACH, THE PILOT COULD NOT OBTAIN A GEAR DOWN AND LOCKED INDICATION ON THE LEFT MAIN LANDING GEAR. HE ELECTED TO LAND GEAR UP WHICH CAUSED SUBSTANTIAL DAMAGE TO THE BOTTOM OF THE FUSELAGE. POSTACCIDENT TESTS REVEALED THAT THE LEFT MAIN LANDING GEAR DOWN LOCK SWITCH HAD FROZEN FROM AN ACCUMULATION OF ICE. WEATHER CONDITIONS AT THE TIME INCLUDED ICING, LOW CEILINGS AND LOW VISIBILITY. PRIOR TO THE ACCIDENT, THE PILOT REPORTED ACCUMULATIONS OF MODERATE ICE. FOLLOWING THE ACCIDENT, ICE ACCUMULATION OF UP TO 3 INCHES WAS FOUND ON THE AIRCRAFT.
Probable cause
A FALSE UNSAFE LANDING GEAR INDICATION DUE TO A FROZEN DOWN LOCK SWITCH. FACTORS WERE: ICING CONDITIONS AND LOW CEILINGS.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN92LA012
- Event ID
- 20001212X18442
- Case number
- DEN92LA012
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 6339edc923959c4a13cc08080048e6e80d1f18ec95347dae0eedf6a4f4995d12; retrieved 2026-09-18T18:50:13.933Z.