Piper PA-23-150 accident near Diablo, California, June 6, 1993
On June 6, 1993 at about 6:50 pm local time, a Piper PA-23-150, registered N522T, was destroyed in an accident near Diablo, California. It was a personal flight under general aviation rules (Part 91). 2 people were killed. The weather was instrument conditions (cloud, fog or low visibility).
The NTSB's probable cause their words, unchanged
THE PILOT IN COMMAND'S CONTINUED FLIGHT INTO INSTRUMENT METEOROLOGICAL CONDITIONS, AND THE IMPROPER IN FLIGHT PLANNING AND DECISION MAKING BY THE PILOT.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 6, 1993 · about 6:50 pm local time
- Place
- Diablo, California · map
- Type
- Accident
- Injuries
- 2 people were killed.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft
- Piper PA-23-150 · all PA-23-150s on the register
- Registration
- N522T · registry record · serial 23-1067
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE AIRPLANE COLLIDED WITH MOUNTAINOUS TERRAIN IN A NEAR WINGS LEVEL ATTITUDE DURING INSTRUMENT METEOROLOGICAL CONDITIONS. WITNESSES REPORTED NORMAL ENGINE SOUNDS WHEN THE AIRPLANE FLEW OVER THEIR LOCATION. THERE WAS NO RECORD OF THE PILOT OBTAINING A WEATHER BRIEFING PRIOR TO HIS DEPARTURE. THERE WERE NO MECHANICAL FAILURES OR MALFUNCTIONS FOUND DURING AN EXAM OF THE AIRCRAFT WRECKAGE. BOTH PROPELLER'S SHOWED CHORDWISE SCRATCHES AND 'S' BENDING.
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; instrument: airplane
- Flight time: 1,119 hours in all; 18 in the last 90 days; 3 in the last 30 days; 986 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Last inspection: annual inspection, March 4, 1993
- Maximum gross weight: 3,800 lb
- Landing gear: retractable
- Engine: Lycoming O-320 (piston); 0 hours total
- Fire on the ground
The flight
- Departed from: APC Napa CA at 6:25 pm
- Destination: RHV San Jose CA
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Sky: not recorded
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
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.