# NTSB CHI91FA254: Cessna 172M, N61568, Ottumwa, IA, August 6, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: August 6, 1991, 08:11 local (13:11 UTC)
- Place: Ottumwa, IA
- Coordinates: 41.010318, -92.409156 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.0103&lon=-92.4092&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed, report January 27, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 14914
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91FA254
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14914/pdf
- Page: https://openairdocs.org/ntsb/CHI91FA254

## Probable cause

IMPROPER IFR PROCEDURE BY THE PILOT BY NOT MAINTAINING THE PROPER MINIMUM DESCENT ALTITUDE (MDA) UNTIL ESTABLISHED ON THE ILS LOCALIZER AND GLIDEPATH.

## Sequence of events

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

- In flight collision with object, approach - faf/outer marker to threshold (ifr)
  - object - tree(s)
  - minimum descent altitude - not maintained, pilot in command (cause)
  - light condition - dark night
  - weather condition - low ceiling
  - weather condition - fog
  - weather condition - drizzle/mist
  - ifr procedure - improper, pilot in command (cause)
  - proper alignment - not attained, pilot in command
  - proper glidepath - not attained, pilot in command

## Analysis

DURING ARRIVAL, THE PILOT WAS CLEARED FOR AN ILS RUNWAY 31 APPROACH.  AS HE CONTINUED THE APPROACH, THE AIRPLANE DESCENDED INTO TREES AND THE TERRAIN, INSIDE THE OUTER MARKER, 4.0 MILES FROM THE THRESHOLD AND .19 MILE TO THE LEFT OF CENTERLINE.  INITIAL IMPACT WAS ON A HEADING OF 356 DEGREES MAGNETIC AT AN ELEVATION OF 820 FEET MSL.  THE AIRPORT ELEVATION WAS 845 FEET MSL.  MINIMUM DESCENT ALTITUDE (MDA) BEFORE REACHING THE ILS GLIDE SLOPE WAS 2800 FEET; MDA FOR A LOCALIZER ONLY APPROACH WAS 1200 FEET.  DECISION HEIGHT (IF ESTABLISHED ON THE ILS LOCALIZER & GLIDEPATH) WAS 1041 FEET.  SUBSEQUENT INVESTIGATION FAILED TO REVEAL ANY MECHANICAL MALFUNCTION OF THE AIRCRAFT OR SIGNIFICANT WEATHER PHENOMENA WHICH WOULD HAVE RESULTED IN THE ACCIDENT.

## Aircraft

- Registration: [N61568](https://openairdocs.org/deregistered/N61568-1991-10-16), registration cancelled 1991-10-16, S/N 17264646 (OpenAirDocs)
- Reported make and model: CESSNA 172M
- Registry model: [Cessna 172M](https://openairdocs.org/model/cessna-172m) (registry code 2072418) (OpenAirDocs)
- Category: Airplane
- Serial number: 17264646
- Engines: LYCOMING O-320-E2D 150 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Business, Part 91
- Operator: Air Exec, Onc.
- Registered owner: Air Exec, Onc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Unknown, January 2, 2000
- Departed: K27, FORT MADISON, IA
- Destination: OTM, OTTUMWA, IA
- Flight plan: IFR
- Airport: OTM, Ottumwa Industrial, runway 31, 6,499 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 52; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; toxicology performed; flight hours: 529 total

## Weather

- Conditions: Instrument (IMC), Day
- Wind: 110° at 9 knots
- Visibility: 1 statute miles
- Lowest ceiling: 300 ft overcast
- Temperature: 64 °F, dew point 63 °F
- Altimeter: 30.00 inHg
- Observed at: OTM, 2 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 19910806032069A](https://openairdocs.org/incident/19910806032069A), Aug 6, 1991: Cessna 172M, Ottumwa, IA, Destroyed, 2 fatal. Descended below dh on ILS approach. Struck trees and burned. Thunderstorms heavy rain in area.

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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