# NTSB Accident CEN16LA197
> **CESSNA 501** · 2016-05-24 · Texarkana, AR, USA · MINR
## Event
- **NTSB number:** CEN16LA197
- **Event ID:** 20160527X13034
- **Type:** Accident
- **Date:** 2016-05-24
- **Location:** Texarkana, AR, USA
- **Coordinates:** 33.441665, -94.03778
## Injuries
- **Highest injury:** MINR
- **Fatal:** 0
- **Serious:** 0
- **Minor:** 3
- **Uninjured:** 1
- **Total aboard:** 4
## Aircraft
- **Make:** CESSNA
- **Model:** 501
- **Registration:** N804ST
- **FAR Part:** 091
- **Engines:** 2
- **Damage:** SUBS
## Conditions
- **Light:** NDRK
- **Weather:** VMC
## Probable cause

The pilot's failure to use supplemental oxygen as required during high-altitude flight, which resulted in his loss of consciousness following a loss of cabin pressurization. Contributing to the accident was the separation of the air conditioning system's primary pressurization duct and the subsequent failure of the aft pressure bulkhead check valve flapper due to progressive weakening from age.

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*Source: [NTSB CAROL](https://data.ntsb.gov/carol-main-public/basic-search?source=ntsb&type=event&ntsb_number=CEN16LA197) · AI Analytics · CC0 1.0*