Amateur-built M24 accident near Mount Sterling, Illinois, October 16, 2023
On October 16, 2023 at about 4:30 pm local time, a 2020 amateur-built M24 (gyroplane), registered N90HM, was substantially damaged in an accident during approach (VFR pattern downwind) near Mount Sterling, Illinois (Mount Sterling Municpal airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
The pilot’s failure to maintain gyroplane control on the downwind leg, which resulted in impact with terrain. Contributing to the accident was the pilot’s distraction.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 16, 2023 · about 4:30 pm local time
- Place
- Mount Sterling, Illinois · Mount Sterling Municpal · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built M24, built 2020
- Registration
- N90HM · registry record · serial 24169824
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that, while on the downwind leg of the traffic pattern, he was distracted while looking for other traffic in the pattern when he noticed that his airspeed had decayed to 37 mph, below the aircraft flight manual’s recommended traffic pattern airspeed of 65 mph. The pilot attempted to correct by increasing engine throttle but subsequently lost control. The gyroplane impacted terrain while in the left downwind leg, which resulted in substantial damage to the main rotor system and empennage. Postaccident examination of the gyroplane revealed no preaccident mechanical failures or malfunctions that would have precluded normal operation. Based on the available information, the pilot likely unloaded the rotor blades inadvertently, known as buntover, when he applied engine throttle to correct for the decaying airspeed. The sudden throttle application caused the gyroplane to abruptly pitch forward and tumble. The FAA Rotorcraft Flying Handbook notes that, in most cases, the proper recovery procedure for the condition is to immediately remove power and load the rotor blades.
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 control in flight during approach (VFR pattern downwind) defining event
The NTSB's findings
- Aircraft › Aircraft propeller/rotor › Main rotor system › (general) › Incorrect use/operation
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Prop/rotor parameters › Not attained/maintained
- Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Personnel issues › Psychological › Attention/monitoring › Task monitoring/vigilance › Pilot
- Personnel issues › Task performance › Use of equip/info › Use of equip/system › Pilot
Pilot
- Certificate: sport pilot
- Ratings: rotorcraft: gyroplane
- Flight time: 371 hours in all; 215 in this make and model
- Last flight review: September 24, 2023
- Medical certificate: Sport Pilot
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 238 hours
- Last inspection: 100-hour inspection, June 9, 2023
- Maximum gross weight: 992 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 914UL (piston); 278 hours total
The flight
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 320° at 6 knots
- Visibility: 10 statute miles
- Sky: a few clouds at 2,400 ft
- Temperature: 55°F (13°C), dew point 45°F (7°C)
- Altimeter: 30.16 inHg
- Observation at 11:54 am from KUIN, 18 miles away
Weather report (METAR): KUIN 161654Z AUTO 32006KT 10SM FEW024 13/07 A3016 RMK AO2 SLP214 T01330067 $=
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
7 documents, released by the NTSB on October 22, 2025. 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, 9 pages | View Download |
| 2 | Photo Array | PDF, 2 pages | View Download |
| 3 | Examination Summary | PDF, 4 pages | View Download |
| 4 | Gryroplane Flight Manual Excerpt | PDF, 1 page | View Download |
| 5 | FAA Rotorcraft Flying Handbook Excerpt | PDF, 1 page | View Download |
| 6 | Engine Run Video | MOV file | Download |
| 7 | Mx Record Excerpt | PDF, 2 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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 CEN24LA013.