Amateur-built THORP T-18 accident near San Antonio, Texas, August 28, 2021
On August 28, 2021 at about 8:37 pm local time, a 1980 amateur-built THORP T-18, registered N78DW, was substantially damaged in an accident during initial climb near San Antonio, Texas (Boerne Stage Airport). It was a personal flight under general aviation rules (Part 91). 2 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The loss of engine power after takeoff for undetermined reasons.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 28, 2021 · about 8:37 pm local time
- Place
- San Antonio, Texas · Boerne Stage Airport · map
- Type
- Accident
- Injuries
- 2 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built THORP T-18, built 1980
- Registration
- N78DW · registry record · serial 844
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot was planning a short cross-country flight with his passenger. Prior to takeoff, he fueled the airplane with 10-15 gallons of fuel and added one quart of oil to the engine. He performed an engine run-up that included checking the carburetor heat. The takeoff and initial climb were normal, but as he turned the airplane onto the downwind leg to depart the traffic pattern, the engine began running rough and lost total power. The pilot attempted to regain engine power by adjusting the engine mixture, but no change in engine performance was noted. Unable to maintain altitude, he performed a forced landing into trees. The airplane came to rest on its nose and sustained substantial damage. Postaccident examination of the engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Weather conditions reported at the time of the accident were conducive for serious carburetor icing at glide power. However, the pilot applied the carburetor heat during the engine run-up before takeoff, which should have either melted any ice that may have accumulated on the ground or resulted in a rough running engine, which the pilot did not report. The application of carburetor heat during the run-up combined with the high-power setting during takeoff and initial climb reduced the likelihood of carburetor ice.
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
- Loss of engine power (total) during initial climb
- Collision with terrain or object (not controlled flight into terrain) during emergency descent
- Fuel related during initial climb
- Unknown or undetermined during initial climb defining event
The NTSB's findings
- Aircraft › Aircraft power plant › Engine (reciprocating) › (general) › Inoperative
- Environmental issues › Conditions/weather/phenomena › Temp/humidity/pressure › Conducive to carburetor icing › Effect on operation
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instrument: airplane
- Flight time: 8,000 hours in all; 43 in this make and model; 103 in the last 90 days; 24 in the last 30 days; 5,000 as pilot in command
- Last flight review: December 1, 2020
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: minor injuries
The aircraft
- Airframe total time: 880 hours
- Last inspection: condition inspection, November 15, 2021
- Maximum gross weight: 1,500 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-290-G (piston); 880 hours total
The flight
- Destination: T82 Fredricksburg TX
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 290° at 10 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 4,100 ft
- Temperature: 81°F (27°C), dew point 73°F (23°C)
- Altimeter: 29.92 inHg
- Observation at 3:51 pm from KSAT, 9 miles away
Weather report (METAR): KSAT 282051Z 29010KT 10SM -RA BKN041 BKN065 BKN250 27/23 A2992 RMK AO2 RAB11 SLP114 P0006 60006 T02670233 56020=
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
5 documents, released by the NTSB on January 20, 2023. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 11 pages | View Download |
| 2 | Pilot Statement | PDF, 1 page | View Download |
| 3 | Record of Conversation FAA Inspector | PDF, 1 page | View Download |
| 4 | FAA Saib Carburetor Icing Prevention | PDF, 3 pages | View Download |
| 5 | Photograph | PDF, 1 page | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.