Airbus AS 350 B2 N71HD incident near Los Angeles, California

Probable cause

an inflight collision with a hard object of polycarbonate construction, with size and features consistent with that of a small UAS (drone).

NTSB analysis

The helicopter was operating under the provisions of 14 CFR Part 91 as an electronic news gathering flight, under visual flight rules, within Class G airspace. The pilot heard a noise which he first thought might be a bird strike, and made a precautionary landing. Post flight examination led the pilot and operator to believe they collided with a drone.

A search by ground and electronic methods did not locate a drone.

Laboratory examinations indicated that the shape and dimensions of the damage to the horizontal stabilizer were consistent with the configuration and dimensions of many popular small drones. A small mark inside the larger round dent was consistent with the propeller shaft diameter of common small drones.

Infrared examination revealed material transfer of polycarbonate polymer, which is a commonly used construction material of small drones. Although many items which could come in contact with the helicopter as ground FOD, are manufactured of polycarbonate (e.g. safety glasses, light lenses), the shape and configuration of the indentations and scuffs were very consistent with a small drone.

The reported collision occurred in Class G airspace, but higher than the 14 CFR Part 107 regulatory maximum of 400 feet agl for small drones. A provision in Part 107 allows for operations above 400 feet if the drone is within 400 feet laterally of a tall structure. Downtown Los Angeles was approximately ¼ mile away from the collision site, therefore, although the altitude and location are not authorized for drones without a waiver, it is not inconceivable that a drone operator could have been operating near the tall buildings, and deviated or exceeded the lateral requirements.

Although no drone was located, preventing complete certainty, all the available evidence was consistent with a collision with a small UAS.

Text from the NTSB. Open the NTSB docket for DCA20IA034 for the full record.