Cessna R172K accident near Mammoth Lakes, California, July 21, 2001
On July 21, 2001 at about 7:30 pm local time, a Cessna R172K, registered N736YR, was destroyed in an accident near Mammoth Lakes, California (Mammoth Yosemite airport). 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
The pilot's inadequate in-flight planning and his failure to maintain sufficient altitude above the terrain. Factors were the high terrain and the blind canyon.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 21, 2001 · about 7:30 pm local time
- Place
- Mammoth Lakes, California · Mammoth Yosemite · map
- Type
- Accident
- Injuries
- 2 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna R172K · all R172Ks on the register
- Registration
- N736YR · no longer on the register · serial 1722898
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot stated that while en route from Van Nuys to Mammoth Yosemite (MMH) via the Friant VOR radial 023, he entered a canyon and later realized that he had entered the wrong one. He said that the canyon was closed and above his altitude. He also stated that he was experiencing moderate turbulence from the time he entered the canyon up to the accident. The pilot began a "full power climb" at 75 knots in an attempt to clear the ridgeline at the end of the canyon. When he realized that he would not clear the terrain, he began a steep left turn. During the turn, the stall warning was activated and the pilot lowered the nose and shallowed the bank angle. He stated that the airplane struck trees on the top of the canyon edge, tearing off the left wing with the airplane striking the ground in a level attitude. He stated that, "The engine was working properly and all the gauges were in the green." According to the San Francisco sectional chart, the Mammoth Pool Reservoir, which is 55 nautical miles southwest of the MMH airport on a magnetic bearing of 213 degrees, is directly under the 023-degree radial of the Friant VOR. The pilot stated that when he saw the reservoir, he turned east toward the MMH airport. The magnetic course from the reservoir to the MMH airport was 033 degrees, or a northeasterly direction. There was a canyon leading northeast from the Mammoth Pool Reservoir along the Friant 023-degree radial, which is also Victor 230. The canyon terminated at Mammoth Lakes, which is 11 miles due west of the MMH airport. Had the pilot followed Victor 230 until reaching the Mammoth Pools, then turned to an easterly heading, he would have been proceeding directly to the airport.
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: private
- Ratings: single-engine land
- Flight time: 250 hours in all; 2 in this make and model; 1 in the last 90 days; 1 in the last 30 days; 200 as pilot in command
- Last flight review: May 10, 2001
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 3,366.6 hours
- Last inspection: annual inspection, December 22, 2000; 57.5 hours since
- Maximum gross weight: 2,550 lb
- Seats: 4
- Landing gear: fixed
- Engine: Continental IO-360-K (piston); 0 hours total
The flight
- Departed from: VNY Van Nuys CA at 5:00 pm
- Destination: MMH Mammoth Lakes CA
- Flight plan: none
- Runway 09, 7,000 ft by 100 ft
Weather at the time
- Light: daylight
- Wind: from 210° at 18 knots, gusting 23
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 27°F (-3°C)
- Altimeter: 30.15 inHg
- Observation at 7:52 pm from KMMH, 11 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| 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.