Robinson Helicopter R44 accident near Sonora, Texas, April 18, 2018
On April 18, 2018 at about 4:00 pm local time, a 2006 Robinson Helicopter R44, registered N4487D, was substantially damaged in an accident during maneuvering (low-alt flying) near Sonora, Texas. It was an aerial observation flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot’s failure to maintain clearance from trees while maneuvering at a low altitude.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 18, 2018 · about 4:00 pm local time
- Place
- Sonora, Texas · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Robinson Helicopter R44 UNDESIGNAT, built 2006 · all R44s on the register
- Registration
- N4487D · no longer on the register · serial 1654
- Damage
- Substantial damage
- Flight
- Aerial observation flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that, while he was spotting deer, the helicopter hit a treetop, damaging the tail rotor. The helicopter began to spin, and the pilot closed the throttle. He landed the helicopter, and it then rolled onto its left side. The helicopter sustained substantial damage to the tailboom and fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. The pilot's recommendation was to fly at a higher and safer altitude.
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
- Low altitude operation/event during maneuvering (low-alt flying) defining event
- Collision with terrain or object (not controlled flight into terrain) during maneuvering (low-alt flying)
- Loss of control in flight during maneuvering (low-alt flying)
- Roll over during landing
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Altitude › Not attained/maintained
- cause Personnel issues › Psychological › Attention/monitoring › Monitoring environment › Pilot
- cause Environmental issues › Physical environment › Object/animal/substance › Tree(s) › Effect on operation
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; rotorcraft: helicopter
- Flight time: 12,882 hours in all; 9,558 in this make and model; 374 in the last 90 days; 47 in the last 30 days; 12,371 as pilot in command
- Last flight review: August 19, 2016
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 3,719.6 hours
- Last inspection: 100-hour inspection, April 6, 2018
- Maximum gross weight: 2,400 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming O-540-F1B5 (piston); 625 hours total
The flight
- Flight plan: not recorded
Weather at the time
- Light: daylight
- Wind: from 010° at 12 knots, gusting 21
- Visibility: 10 statute miles
- Sky: broken clouds at 2,300 ft
- Temperature: 70°F (21°C), dew point 59°F (15°C)
- Altimeter: 30.11 inHg
- Observation at 4:15 pm from KECU, 22 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 2 |
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 N4487D the same tail number, which may have belonged to a different aircraft at the time
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.