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WPR22FA023 · Mooney M20M

28 Oct 2021 · Snoqualmie, WA, United States

Another Greaser Mooney M20M · Accident: structural icing en route

From Arlington Municipal Airport (AWO) to TWC · Twin Falls, ID

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Event

NTSB case
WPR22FA023
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
1 · all aircraft and ground
Ground fatalities
Unknown
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
General aviation
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

Mooney M20M

Aircraft type
Mooney M20
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
N40KA
Onboard fatalities
Unknown
Route
From Arlington Municipal Airport (AWO), Arlington, WATo TWC · Twin Falls, ID
Aircraft age
About 28 years (built 1993)
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 91: General Aviation
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
En route · climb to cruise
Defining eventThe 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
Structural icing
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

  • Environmental issues › Conditions/weather/phenomena
  • Personnel issues › Action/decision
  • Personnel issues › Task performance

Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.

NTSB narrative

After a 6-year hiatus from flying, the pilot had just purchased the airplane. The morning of the accident flight, he filed an instrument flight rules (IFR) flight plan and received a weather briefing that identified icing conditions along the planned flight route. The pilot departed the airport about 0842 and planned to climb to an altitude of 17,000 ft mean sea level (msl). About 0901, the controller cleared the pilot to depart 14,000 ft msl and climb to 17,000 ft msl. Subsequently, the controller informed the pilot of multiple PIREPs for icing conditions from 12,000 ft msl to 18,000 ft msl and offered the pilot an altitude of 19,000 ft msl to get above the icing, which the pilot accepted. About 0904, after climbing to an altitude of 16,300 ft msl, the airplane began a rapid descent with a series of tight spiral turns. Communication between the controller and the pilot became broken and unreadable. An airplane operating in the area relayed to the controller that the pilot reported being out of control. Shortly after 0910 radar contact was lost, and the airplane impacted terrain. It is likely that the accident airplane encountered structural icing and that the erratic turns coupled with a rapid descent rate were indicative of the pilot’s loss of airplane control, which resulted in a collision with terrain. Postaccident examination of the engine and airframe revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The supplement to the pilot’s operating handbook and the airplane flight manual contained a warning that stated, “INTENTIONAL FLIGHT INTO KNOWN ICING IS PROHIBITED.” The pilot’s logbook contained no record of a recent instrument proficiency check.

Probable cause

The pilot’s decision to fly the airplane into known icing conditions, which resulted in a loss of airplane control and collision with terrain.

Verbatim NTSB analysis and probable cause from the NTSB dataset

Sources

NTSB record WPR22FA023
Event ID
20211029104178
Case number
WPR22FA023
Dataset
full-current
Source SHA-256
5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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, coordinates, cause areas. 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: 3e49d5427b6513cf886551fbb7318f7ed373cecea32c00043fa0243f2a690d64; retrieved 2026-09-15T07:36:27.618Z.