Cessna 150D accident near San Ygnacio, Texas, April 6, 1991
On April 6, 1991 at about 4:55 pm local time, a Cessna 150D, registered N4437U, was destroyed in an accident near San Ygnacio, Texas. It was a personal flight under general aviation rules (Part 91). 2 people were seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
POWER LOSS DUE TO CARBURETOR ICE AND A MALFUNCTIONING CARBURETOR HEAT CONTROL AND THE PILOT'S LOSS OF CONTROL OF THE AIRPLANE.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 6, 1991 · about 4:55 pm local time
- Place
- San Ygnacio, Texas · map
- Type
- Accident
- Injuries
- 2 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 150D · all 150Ds on the register
- Registration
- N4437U · no longer on the register · serial 15060437
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE PIC ASKED THE PASSENGER RIDING IN THE LEFT SEAT IF HE WANTED TO SEE HOW THE AG PILOTS FLEW. HE REDUCED POWER TO IDLE AND DOVE DOWN TOWARD AN OPEN FIELD. AFTER TRAVERSING THE FIELD THE PILOT ADDED POWER AND THE PASSENGER HEARD A 'POP OR BANG' NOISE FROM THE ENGINE AND THE PILOT SAID 'OH MY GOD'. THE AIRPLANE SUBSEQUENTLY IMPACTED IN THE FIELD IN A SHALLOW NOSE DOWN ATTITUDE AND A SLIGHT LEFT BANK AND CART-WHEELED. INVESTIGATION REVEALED THAT CONDITIONS WERE PRESENT FOR CARBURETOR ICING AND THAT THE CARBURETOR ACCELERATOR PUMP WAS NOT ACTUATING SMOOTHLY. THE CARBURETOR HEAT CONTROL WAS FOUND JAMMED TO THE FULL ON POSITION FOLLOWING THE ACCIDENT; HOWEVER, IT COULD NOT BE DETERMINED IF THAT WAS THE CONDITION PRIOR TO IMPACT.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land
- Flight time: 384 hours in all; 384 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 3,266 hours
- Last inspection: annual inspection, March 18, 1990; 114 hours since
- Maximum gross weight: 1,600 lb
- Seats: 2
- Landing gear: fixed
- Engine: Continental O-200-A (piston); 0 hours total
The flight
- Departed from: NONE Zapata TX at 4:00 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 010° at 6 knots
- Visibility: 8 statute miles
- Sky: overcast at 3,500 ft; scat at 1,500 ft
- Temperature: 68°F (20°C), dew point 57°F (14°C)
- Altimeter: 30.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.