# NTSB DEN85LA060: Beech B36TC, N6750C, Billings, MT, January 5, 1985

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: January 4, 1985, 18:25 local (Jan 5, 1985, 01:25 UTC)
- Place: Billings, MT
- Location: 45.8078° N, 108.5435° W: Placed by OpenAirDocs at BILLINGS LOGAN INTL (BIL), within about a mile (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=45.8078&lon=-108.5435&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor, 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16624
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN85LA060
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16624/pdf
- Page: https://openairdocs.org/ntsb/DEN85LA060

## Sequence of events

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

- Miscellaneous/other, cruise
  - oxygen system - improper use of, pilot in command (cause)
  - incapacitation(anoxia/hypoxia), pilot in command (contributing factor)
  - aircraft handling - performed, unqualified person
- In flight collision with terrain/water, approach - vfr pattern - final approach
  - control interference - improper, pilot in command (cause)
  - proper descent rate - exceeded, pilot in command (cause)
  - remedial action - attempted, unqualified person

## Analysis

PLT USED CANNULA CONNECTED TO PORTABLE OXYGEN SYSTEM DURING CLIMB STARTING AT 11,000 FT MSL. AT FL 170 PLT SWITCHED TO A MASK CONNECTED TO ACFT OXYGEN STSTEM. AT FL 250, PLT COMPLAINED OF STOMACH PAINS FOR APRX 1/2 HR. PLT THEN STATED TO HIS SON THAT HIS OXYGEN SMELT BAD, THE MASK WAS AWKWARD TO USE AND IT FIT POORLY. AT THIS TIME THE PLT USED THE MASK AND CANNULA TOGETHER. THE ACFT OXYGEN SYSTEM WAS CHECKED AND INDICATED A POSITIVE FLOW WITH A BOTTLE PRESSURE OF 1500 PSI. PLT THEN BEGAN SHOWING SIGNS OF HYPOXIA AND SUBSEQUENTLY DRIFTED IN AND OUT OF CONSIOUSNESS. PLTS SON TOOK OVER CONTROLS, DECLARED AN EMERGENCY AND FLEW THE ACFT UNTIL FINAL APCH WHEN THE PLT TOOK CONTROL OF ACFT. PLT DIVED ACFT ON SHORT FINAL AND SON PULLED BACK ON YOKE. ACFT CONTACTED GROUND SHORT OF THE RWY. INSPECTION OF THE ACFT OXYGEN SYSTEM REVEALED NO MECHANICAL MALFUNCTION, HOWEVER, THE OXYGEN BOTTLE REPORTEDLY HAD AN APRX DEW POINT OF -35 DEG F. OXYGEN USED FOR AVIATION IS REQUIRED TO HAVE A DEW POINT OF -83 DEG F OR LESS.

## Aircraft

- Registration: [N6750C](https://openairdocs.org/deregistered/N6750C-2007-12-18), registration cancelled 2007-12-18, S/N EA-393, built 1984 (OpenAirDocs)
- Reported make and model: BEECH B36TC
- Registry model: [Beech B36TC](https://openairdocs.org/model/beech-b36tc) (registry code 1151609) (OpenAirDocs)
- Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 393
- Airframe hours: 218
- Engines: CONTINENTAL TSIO-520-UB 300 horsepower reciprocating
- Damage: Substantial damage
- Flight: Business, Part 91
- Registered owner: William Nibbelink
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, September 20, 1984, 20 hours before
- Departed: SEATTLE, WA
- Destination: BIL, BILLINGS, MT
- Flight plan: IFR
- Airport: BIL, Logan, runway 22, 5,704 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left

## Weather

- Conditions: Visual (VMC), Night/bright
- Wind: 220° at 17 knots
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: 50 °F
- Altimeter: 30.00 inHg
- Observed at: BIL

## 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 19850104001279A](https://openairdocs.org/incident/19850104001279A), Jan 4, 1985: Beech B36TC, Billings, MT, Substantial damage. Built in oxygen tank contaminated with water. Pilot hypoxic. Passenger flew to final, pilot then landed short.

## Other investigations on N6750C (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 MIA07LA133](https://openairdocs.org/ntsb/MIA07LA133), Aug 18, 2007: Beech B36TC (N6750C), Clearwater, FL, substantial damage. Probable cause: The pilot's improper rotation and climb during the takeoff which resulted in a stall/mush, a descent, and an impact with the ground.

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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