# NTSB DEN89LA074: Piper PA-18-150, N4355Z, Boulder, CO, February 8, 1989

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: February 8, 1989, 14:10 local (21:10 UTC)
- Place: Boulder, CO
- Coordinates: 40.019157, -105.250587 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.0192&lon=-105.2506&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report September 28, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 17671
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN89LA074
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17671/pdf
- Page: https://openairdocs.org/ntsb/DEN89LA074

## Probable cause

FAILURE OF THE DUAL STUDENT TO MAINTAIN DIRECTIONAL CONTROL AND THE FAILURE OF THE PILOT IN COMMAND (CFI), TO PROVIDE ADEQUATE REMEDIAL ACTION IN A TIMELY MANNER, TO CORRECT THE SWERVE. A SECOND PROBABLE CAUSE WAS THE CFI'S FAILURE TO PROVIDE ADEQUATE SUPERVISION DURING THE LANDING ROLL. INADEQUATE CREW COORDINATION IS CONSIDERED A FACTOR.

## Sequence of events

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

- Loss of control - on ground/water, landing - roll
  - crew/group coordination - inadequate, pilot in command(cfi) (contributing factor)
  - touch-and-go - initiated, dual student
  - directional control - not maintained, dual student (cause)
  - supervision - inadequate, pilot in command(cfi) (cause)
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - snowbank
- Nose over, landing - roll

## Analysis

THE ATP RATED CFI WAS PERFORMING A RENTAL CHECKOUT WITH A PRIVATE PLT. THE CHECK PLT TOLD THE PLT TO MAKE A LANDING AND 'IF SUFFICIENT RUNWAY REMAINED,' TO MAKE ANOTHER TAKEOFF. A LANDING WAS COMPLETED ON RWY 8R, A 4,100 X 75 FT ASPHALT RWY. THE CHECK PILOT HAD BEEN FOLLOWING THROUGH ON THE CONTROLS BUT DURING THE LANDING ROLL HE RELEASED THE CONTROLS AND WAITED FOR THE PLT TO STOP. HE SAID THAT AS SOON AS HE REMOVED HIS HANDS FROM THE CONTROLS, THE STICK WENT FORWARD AND HE HEARD THE ENGINE SPEED UP. THE AIRPLANE SWERVED TO THE LEFT. THE CHECK PLT TOOK THE CONTROLS AND ATTEMPTED TO CORRECT THE SWERVE, TO NO AVAIL. THE PLANE STRUCK A SNOW DRIFT ON THE LEFT SIDE OF THE RWY AND NOSED OVER.

## Aircraft

- Registration: [N4355Z](https://openairdocs.org/aircraft/N4355Z), registered now, S/N 18-8673 (OpenAirDocs)
- Reported make and model: PIPER PA-18-150
- Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 18-8673
- Airframe hours: 3545
- Engines: LYCOMING O-320-A2B 150 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Boulder Flying Service
- Registered owner: Lloyd D. Carr & Donna R. Carr
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, November 11, 1988, 74 hours before
- Departed: 1V5
- Destination: 1V5
- Airport: 1V5, Boulder Municipal

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 34; flight instructor, commercial, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: rear; flight hours: 2,215 total, 165 in this make and model, 2,096 as pilot in command, 64 in the last 90 days, 46 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 18 °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 19890208002059A](https://openairdocs.org/incident/19890208002059A), Feb 8, 1989: Piper PA18150, Boulder, CO, Substantial damage. CFI relaxed vigilance and beleived student was stopping but student began go around. Plane hit snowbank. Nosed over

## Other investigations on N4355Z (1)

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.

- [NTSB MKC70D0151](https://openairdocs.org/ntsb/MKC70D0151), Jul 2, 1969: Piper PA-18 (N4355Z), Crary, ND, substantial damage

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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