Cessna 150L accident near Silverton, Colorado, July 14, 2011
On July 14, 2011 at about 1:30 pm local time, a 1971 Cessna 150L, registered N1539Q, was substantially damaged in an accident during maneuvering (low-alt flying) near Silverton, Colorado. It was a personal flight under general aviation rules (Part 91). 2 people were killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's failure to maintain control of the airplane while operating it at low levels above mountainous terrain and in excess of its maximum allowable gross weight, which resulted in an aerodynamic stall. The pilot's failure to maintain control resulted from an acute cardiac event and incapacitation, hypoxia, or the effects of sedating medications or a combination of these factors. Contributing to the accident was the pilot's improper decision to takeoff above gross weight and without oxygen for the flight in mountainous terrain.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 14, 2011 · about 1:30 pm local time
- Place
- Silverton, Colorado · map
- Type
- Accident
- Injuries
- 2 people were killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 150L, built 1971 · all 150Ls on the register
- Registration
- N1539Q · no longer on the register · serial 15072839
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
A witness saw the airplane flying low over mountainous terrain. He then saw the nose of airplane pull up, followed by the airplane flying inverted and departing controlled flight; the airplane's observed behavior is indicative of an aerodynamic stall. The airplane impacted rocky terrain at 12,570 feet mean sea level. The airplane was operating in excess of its maximum allowable gross weight. Further, the pilot was not using supplemental oxygen, despite a risk for hypoxia above 10,000 feet. The postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The pilot's autopsy indicated moderate to severe diffuse coronary artery disease. This elevated his risk for acute coronary syndrome or an acute arrhythmia followed by incapacitation but would have left no evidence at autopsy. Further, hypoxia would have increased the likelihood of an acute cardiac event. Additionally, the pilot had significant levels of multiple impairing medications at the time of the crash that would have affected his ability to operate the airplane. The pilot was very likely impaired by this combination of sedating medications, even at levels that were probably therapeutic. Further, the medications would have affected his decision-making ability, which may have played a role in his decision to fly at these altitudes without oxygen and above the airplane's maximum gross weight.
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
What happened, in order
- Miscellaneous/other during prior to flight
- Loss of control in flight during maneuvering (low-alt flying) defining event
- Collision with terrain or object (not controlled flight into terrain) during maneuvering (low-alt flying)
- Part(s) separation from AC during post (impact)
The NTSB's findings
- cause Personnel issues › Action/decision › Action › Incorrect action selection › Pilot
- cause Personnel issues › Physical › Impairment/incapacitation › Hypoxia/anoxia › Pilot
- cause Personnel issues › Physical › Impairment/incapacitation › Cardiovascular › Pilot
- cause Personnel issues › Physical › Impairment/incapacitation › Prescription medication › Pilot
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › (general) › Not attained/maintained
- factor Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
- Environmental issues › Physical environment › Terrain › Mountainous/hilly terrain › Not specified
- cause Aircraft › Aircraft oper/perf/capability › Aircraft capability › Maximum weight › Capability exceeded
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 4,125 hours in all; 758 in this make and model
- Last flight review: February 16, 2010
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: fatal
Passenger
- Seat: rgt
- Injury: fatal
The aircraft
- Airframe total time: 4,000 hours
- Last inspection: annual inspection, July 2, 2011; 11 hours since
- Maximum gross weight: 1,600 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-320-E2D (piston); 827 hours total
The flight
- Departed from: 00C Durango CO at 12:45 pm
- Destination: 00C Durango CO
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 120° at 3 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 55°F (13°C), dew point 39°F (4°C)
- Altimeter: 30.30 inHg
- Observation at 1:35 pm from KTEX, 17 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
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.