Cosmos PHASE II accident near Prineville, Oregon, May 2, 2026
On May 2, 2026 at about 4:53 pm local time, a 2003 Cosmos PHASE II (weight-shift aircraft), registered N145W, was substantially damaged in an accident during landing near Prineville, Oregon (Prineville 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).
The NTSB's probable cause their words, unchanged
The pilot's inability to maintain directional control during the landing roll due to a flat tire.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 2, 2026 · about 4:53 pm local time
- Place
- Prineville, Oregon · Prineville · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cosmos PHASE II, built 2003 · all PHASE IIs on the register
- Registration
- N145W · registry record · serial B0380
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot of the weight-shift control trike reported that, while landing, the trike touched down and started to oscillate back and forth. Subsequently, the trike rolled over, which resulted in substantial damage to the wing and the wing mast. According to the pilot, after the accident he observed the right rear tire was flat and would not inflate during the postaccident examination. No other preaccident mechanical failures or malfunctions with the trike that would have precluded normal operation. It is likely the tire was deflated during touchdown, and the additional drag generated by the flat tire likely contributed to the oscillations during landing.
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 on ground during landing defining event
- Roll over during landing (landing roll)
The NTSB's findings
- Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Directional control › Not attained/maintained
- Aircraft › Aircraft systems › Landing gear system › Landing gear/wheel fairing › Damaged/degraded
Pilot
- Certificate: sport pilot
- Flight time: 171 hours in all; 1 in the last 90 days; 2 in the last 30 days; 136 as pilot in command
- Last flight review: March 2, 2026
- Medical certificate: Sport Pilot
- Seat: ctr
- Injury: no injuries
The aircraft
- Airframe total time: 350 hours
- Last inspection: inspection type not recorded
- Maximum gross weight: 960 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 503 (piston); 250 hours total
The flight
- Flight plan: none
- Runway 18/3, 300 ft by 75 ft
Weather at the time
- Light: daylight
- Wind: from 020° at 3 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 61°F (16°C), dew point 43°F (6°C)
- Altimeter: 29.98 inHg
- Observation at 10:00 am from KRDM, 10 miles away
Weather report (METAR): METAR KRDM 021656Z 02003KT 10SM CLR 16/06 A2998 RMK AO2 SLP134 T01610056
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Photographs from the investigation 1 picture from the NTSB's docket, as the NTSB released them
The NTSB's photographs with the NTSB's captions, at screen size. Open a picture to see it full size or to report one that should not be shown.
Documents from the investigation the NTSB's docket: the evidence folder behind the report
2 documents, released by the NTSB on August 27, 2026. 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, 10 pages | View Download |
| 2 | Investigation Photographs | PDF, 4 pages · our copy | 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.