# NTSB FTW91FA027: Cessna 421B, N421H, Muskogee, OK, January 6, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: January 5, 1991, 20:43 local (Jan 6, 1991, 02:43 UTC)
- Place: Muskogee, OK
- Location: 35.7479° N, 95.3697° W: Placed by OpenAirDocs: center of Muskogee, OK, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=35.7479&lon=-95.3697&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 6 fatal
- Status: Completed, report June 2, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 23240
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW91FA027
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/23240/pdf
- Page: https://openairdocs.org/ntsb/FTW91FA027

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN CONTROL OF THE AIRCRAFT, DUE TO SPATIAL DISORIENTATION.  FACTORS RELATED TO THE ACCIDENT WERE: DARKNESS, ADVERSE WEATHER CONDITIONS, AND THE PILOT'S PHYSICAL IMPAIRMENT FROM THE CHRONIC SINUS INFECTION.

## Sequence of events

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

- Loss of control - in flight, takeoff - initial climb
  - light condition - dark night (contributing factor)
  - weather condition - fog (contributing factor)
  - weather condition - low ceiling (contributing factor)
  - weather condition - rain (contributing factor)
  - maintenance - inadequate, company/operator management
  - aircraft control - not maintained, pilot in command (cause)
  - spatial disorientation, pilot in command (cause)
  - physical impairment(other organic problem), pilot in command (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

A PLT (WHOSE INSTRUMENT CURRENCY COULD NOT BE DTRMD) TOOK OFF AT NGT IN IMC. SHORTLY AFTER TAKEOFF, THE ACFT CRASHED ABT 1.5  MI FM THE DEP END OF THE RWY. THERE WAS EVIDENCE THAT IT IMPACTED IN AN 85 DEG RGT BANK, NOSE DWN ATTITUDE AT HI SPEED. NO PREIMPACT PART FAILURE WAS FND DRG THE INVESTIGATION; HOWEVER, DRG A PRE-PURCHASE INSPN ON 10/16/90, SVRL DISCREPANCIES WERE NOTED. THESE INCLUDED AN INOP FLT DRCTR, AN AUTOPLT MALFUNCTION & A MISRIGGED FLT CTL SYS THAT ALLOWED THE CTRL WHEEL TO INDC A LEFT TURN WHEN THE ACFT WAS IN LVL FLT. THERE WAS NO RECORD OF THESE BEING REPAIRED. RECORDS SHOWED THE PITOT-STATIC SYS WAS LAST TESTED ON 3/24/88. THE PLT WAS TAKING SINE-AID & TYLENOL FOR A CHRONIC SINUS INFECTION. ALTHOUGH TOX CHECKS INDCD THE PRESENCE OF 50.7 UG/ML OF PSEUDOEPHEDRINE & 36.4 UG/ML OF ACETAMINOPHEN IN THE PLT'S URINE, NONE WAS FOUND IN HIS BLOOD. THE SINUS COND COULD HAVE AFFECTED THE PLT'S BALANCE & EQUILIBRIUM.

## Aircraft

- Registration: [N421H](https://openairdocs.org/deregistered/N421H-2013-09-13), registration cancelled 2013-09-13, S/N 421B0516, built 1973 (OpenAirDocs)
- Reported make and model: CESSNA 421B
- Registry model: [Cessna 421B](https://openairdocs.org/model/cessna-421b) (registry code 2076014) (OpenAirDocs)
- Registry engine: [Continental GTSIO-520-C](https://openairdocs.org/engine/continental-gtsio-520-c) (registry code 17035, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 421B0516
- Airframe hours: 2580
- Engines: CONTINENTAL GTSIO-520-H2 375 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Personal, Part 91
- Registered owner: Shanks, Ronnie E
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, May 22, 1990, 117 hours before
- Departed: MKO
- Destination: ABQ, ALBUQUERQUE, NM
- Flight plan: IFR
- Airport: MKO, Davis Field, runway 13, 7,200 × 150 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 1,820 total, 684 in this make and model, 1,522 as pilot in command, 20 in the last 90 days, 6 in the last 30 days

## Weather

- Conditions: Instrument (IMC), Night/dark
- Wind: 10° at 10 knots
- Lowest ceiling: 300 ft overcast
- Temperature: 36 °F, dew point 36 °F
- Altimeter: 30.29 inHg
- Observed at: TUL, 40 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 19910106000179A](https://openairdocs.org/incident/19910106000179A), Jan 6, 1991: Cessna 421, Muskogee, OK, Destroyed, 6 fatal. Crashed shortly after takeoff in IMC on a IFR flight plan.

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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