3DR Solo – Accident – 2017-05-10

Drone Manufacturer: 3DR
Drone Model: Solo
Country: United States of America
Type: Accident
Date: 2017-05-10
Applies: Daytime
Pilot Qualifications: Unknown Status
Pilot Flight Experience: Unknown Hours
Link to External Information About This submission: https://www.safecom.gov/safecom/17-0271
File Uploaded: None


In May 2017 Yosemite NP had a missing person SAR in progress and requested UAS assistance from an outside National Park with an established UAS program. One area that ground searchers could not effectively search was below Glacier Point. On the morning of May 10 a UAS operator and 2 visual observers drove to Glacier Point which was closed to visitors. During the first flight, the UAS was having a problem maintaining a stable flight and the operator had to turn GPS off to complete mission and fly UAS back to landing site. After hovering over the landing site, the UAS began to wobble side to side and clipped a bush, damaging a prop. After performing a compass recalibration, the operator attempted another flight, which went smoothly. On the 2nd flight after the compass re-calibration, the operator visually could see the UAS unable to maintain altitude. The operator turned off the GPS and flew the UAS back to the landing site. After establishing a hover, the operator turned GPS back on for the landing and UAS made a sudden, fast descent, made a hard landing, flipped over, and damaged all 4 props.

Reported Cause

It was determined by the operator that there was too much interference affecting the UAS““s GPS. After talking with a Yosemite Ranger bot involved in the search the operator was made aware of a nearby repeater /cell tower. Since turning off the repeater / cell tower was not an option the mission was stopped. While the UAS was in flight the corrective action was to fly manual by turning off the GPS assistance. In a training environment the operator needs to practice landing without GPS assistance.