# NTSB CHI89MA057: Nihon YS-11A-600, N128MP, West Lafayette, IN, March 15, 1989

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Major investigation · Final report
- Date: March 15, 1989, 07:26 local (12:26 UTC)
- Place: West Lafayette, IN
- Coordinates: 40.440299, -86.910743 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.4403&lon=-86.9107&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed, report September 14, 1990
- Report: Approved by Office Director
- Safety recommendations: Yes
- NTSB case key (mKey): 14429
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI89MA057
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14429/pdf
- Page: https://openairdocs.org/ntsb/CHI89MA057

## Probable cause

A LOSS OF CONTROL DUE TO THE IMPROPER INFLIGHT DECISIONS BY THE CREW AND THE UNDETECTED ACCUMULATION OF ICE ON THE LEADING EDGE OF THE HORIZONTAL STABILIZER, DURING FLIGHT IN A FORWARD CENTER OF GRAVITY CONDITION AND EXACERBATED BY THE EXTENSION OF FULL LANDING FLAPS.

## Sequence of events

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

- Loss of control - in flight, approach - vfr pattern - final approach
  - weather condition - icing conditions (contributing factor)
  - in-flight planning/decision - improper, pilot in command (cause)
  - horizontal stabilizer surface - ice (cause)
  - anti-ice/deice system - not used, copilot/second pilot (contributing factor)
  - lowering of flaps - excessive (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - dirt bank/rising embankment (contributing factor)

## Analysis

AN IFR FLIGHT WAS TERMINATED WITH A VISUAL APPROACH. CONDITIONS WERE CONDUCIVE TO AIRFRAME ICING. THE AIRCRAFT WAS BEING POSITIONED EMPTY, WITH A CG AT 22.1% MAC. ON SHORT FINAL, AT APPROXIMATELY 400 FT AGL, 35 DEGREES OF LANDING FLAP WAS SELECTED. THE AIRCRAFT WAS OBSERVED TO PITCH DOWNWARD TO AN UNUSUAL ATTITUDE AND TO ENTER A STEEP DESCENT. A PARTIAL RECOVERY WAS OBSERVED BEFORE THE AIRCRAFT IMPACTED A DIRT HILL 500 FT SHORT OF RWY 28. EXAMINATION OF THE AIRFRAME AFTER THE ACCIDENT REVEALED 1/2 TO 3/4 INCH OF RIME ICE ADHERING TO THE LEADING EDGE OF THE HORIZONTAL STABILIZER. NO ICE WAS FOUND ON ANY OTHER PORTION OF THE AIRFRAME. EVIDENCE IN THE COCKPIT INDICATED THAT ENGINE, PITOT, AND WINDSHIELD ANTI-ICE SYSTEMS WERE ON, BUT WING/EMPENNAGE DEICE WAS OFF. NO EVIDENCE OF A POWERPLANT OR SYSTEMS MALFUNCTION WAS FOUND.

## Aircraft

- Registration: [N128MP](https://openairdocs.org/deregistered/N128MP-1991-06-13), registration cancelled 1991-06-13, S/N 2139 (OpenAirDocs)
- Reported make and model: NIHON YS-11A-600
- Registry model: [Nihon YS-11A](https://openairdocs.org/model/nihon-ys-11a) (registry code 6310410) (OpenAirDocs)
- Category: Airplane
- Serial number: 2139
- Airframe hours: 24088
- Engines: ROLLS-ROYCE DART 542-10J 2680 horsepower turbo prop
- Damage: Destroyed
- Fire: On-Ground
- Flight: Part 121
- Operator: Mid Pacific Airlines
- Registered owner: Koa Holdings, Inc.
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, February 25, 1989, 29 hours before
- Departed: HUF, TERRE HAUTE, IN
- Destination: LAF, WEST LAFAYETTE, IN
- Flight plan: IFR
- Airport: LAF, Purdue University Airport, runway 28, 6,600 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 36; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 7,294 total, 2,097 in this make and model, 6,294 as pilot in command, 61 in the last 90 days, 21 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dawn
- Wind: 280° at 16 knots, gusting 23
- Visibility: 8 statute miles
- Lowest ceiling: 2,200 ft overcast
- Temperature: 32 °F, dew point 25 °F
- Altimeter: 29.00 inHg
- Observed at: LAF, 1 nm away

## 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 19890315004619A](https://openairdocs.org/incident/19890315004619A), Mar 15, 1989: Nihon YS11A600, Lafayette, IN, Destroyed, 2 fatal. Struck dike 500 feet short of runway. Ice on horizontal stabilator.

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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