# NTSB SEA90LA187: Cessna 150D, N4183U, Park City, UT, September 16, 1990

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: September 16, 1990, 09:30 local (15:30 UTC)
- Place: Park City, UT
- Coordinates: 40.6403, -111.489295 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.6403&lon=-111.4893&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report November 9, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 41279
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA90LA187
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41279/pdf
- Page: https://openairdocs.org/ntsb/SEA90LA187

## Probable cause

THE PILOT'S LACK OF UNDERSTANDING OF AIRCRAFT PERFORMANCE AND METEOROLOGICAL CONDITIONS WHEN FLYING AT HIGH DENSITY ALTITUDE IN CLOSE PROXIMITY TO MOUNTAINOUS TERRAIN.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight encounter with weather, maneuvering
  - weather condition - downdraft (contributing factor)
  - weather condition - high density altitude (contributing factor)
  - aircraft performance,climb capability - exceeded (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - mountainous/hilly
  - clearance - not maintained, pilot in command (cause)

## Analysis

THE STUDENT PILOT ENCOUNTERED STRONG UPDRAFTS AND DOWNDRAFTS WHEN CROSSING A RIDGE AT HIGH ALTITUDE IN THE VICINITY OF HIS FAMILY'S CABIN. DUE TO HIGH DENSITY ALTITUDE AND LACK OF CLIMB PERFORMANCE OF THE CESSNA 150D AT SUCH ALTITUDES, HE WAS UNABLE TO SUSTAIN ALTITUDE, AND CRASHED AT APPROXIMATELY 9000 FEET MSL.

## Aircraft

- Registration: [N4183U](https://openairdocs.org/deregistered/N4183U-1991-06-12), registration cancelled 1991-06-12, S/N 15060183 (OpenAirDocs)
- Reported make and model: CESSNA 150D
- Registry model: [Cessna 150D](https://openairdocs.org/model/cessna-150d) (registry code 2071810) (OpenAirDocs)
- Category: Airplane
- Serial number: 15060183
- Engines: CONTINENTAL O-200A 100 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: High Valley Aviation
- Registered owner: Unknown
- Departed: 36U, HEBER CITY, UT

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 23; student; medical: class 3, valid medical--no waivers/lim.; flight hours: 20 total, 20 in this make and model, 6 as pilot in command, 20 in the last 90 days, 18 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 20 knots
- Visibility: 50 statute miles
- Temperature: -0 °F, dew point -0 °F

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19900916039779A](https://openairdocs.org/incident/19900916039779A), Sep 16, 1990: Cessna 150D, Park City, UT, Substantial damage. Flying low over mountain ridge near parents cabin got a downdraft in lee of ridge and crashed into trees.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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