Amateur-built THORP T-18 accident near Colorado City, Colorado, November 24, 1989
On November 24, 1989 at about 2:54 pm local time, a amateur-built THORP T-18, registered N18FL, was destroyed in an accident near Colorado City, Colorado (Greenhorn Valley airport). It was a personal flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
LOSS OF ENGINE POWER WITH CARBON FOULING OF THE SPARK PLUGS, AND FAILURE OF THE PILOT TO MAINTAIN ADEQUATE AIRSPEED, WHICH RESULTED IN AN INADVERTENT STALL.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 24, 1989 · about 2:54 pm local time
- Place
- Colorado City, Colorado · Greenhorn Valley · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built THORP T-18
- Registration
- N18FL · registry record · serial 555
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
A WITNESS SAW THE PLT PREFLIGHT THE ACFT. AFTER HE TOOK OFF, THE ACFT ENTERED A STEEP DESCENT & CRASHED A SHORT DISTANCE FROM THE END OF THE RWY. AN EXAM OF THE ENG REVEALED THAT ALL SPARK PLUGS WERE CARBON FOULED. THE HOME BUILT ACFT HAD A TOTAL OF 40 HRS FLT TIME. THE ENG HAD A TOTAL TIME OF 42 HRS TSMO. THE OWNER/PLT HAD CHANGED THE CARBURETOR & SPARK PLUGS AFTER THE ACFT HAD FLOWN 6 HRS & THE ACFT HAD FLOWN 13 HRS SINCE THE LAST INSPN. NO PREIMPACT PART FAILURE WAS FOUND.
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: 36 in this make and model
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 38 hours
- Last inspection: inspection type not recorded, November 14, 1989; 13 hours since
- Maximum gross weight: 1,560 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-290-G (piston); 0 hours total
The flight
- Departed from: CO22 at 2:50 pm
- Destination: CO22
- Flight plan: none
- Runway 26, 3,900 ft by 36 ft
Weather at the time
- Light: daylight
- Wind: from 250° at 3 knots
- Visibility: 90 statute miles
- Sky: scat at 25,000 ft
- Temperature: 34°F (1°C), dew point 12°F (-11°C)
- Altimeter: 26.00 inHg
- Observation at 2:54 pm from PUB, 25 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 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.
Other NTSB records under N18FL the same tail number, which may have belonged to a different aircraft at the time
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number DEN90DTE01.