NTSB: ‘All available evidence’ shows Helinet mid-air collision was with drone

Avatar for Oliver JohnsonBy Oliver Johnson | July 7, 2020

Estimated reading time 4 minutes, 50 seconds.

A Helinet Aviation Airbus AS350 B2 AStar that was struck by an object while flying near downtown Los Angeles was likely hit by a drone, according to the U.S. National Transportation Safety Board’s (NTSB’s) final report into the incident.

Helinet operates the Airbus AS350 B2 on electronic newsgathering operations for ABC7 News. Skip Robinson Photo
Helinet operates the Airbus AS350 B2 on electronic news gathering operations for ABC7 News. Skip Robinson Photo

None of the three people on board the helicopter were injured, with the pilot making a precautionary landing soon after hearing what he thought might be a bird striking the aircraft.

The collision happened at 7:15 p.m. on Dec. 4, 2019, as the helicopter was performing an electronic news gathering flight for ABC7 News. Known by the station as Air7 HD, it was flying under visual flight rules (VFR) at about 1,100 feet above mean sea level (830 feet above ground level) within Class G airspace at the time – well above the 400 feet above ground level maximum for small drones.

A popular drone is shown against the damaged stabilizer to illustrate its size against the impact marks. NTSB Photo
A popular drone is shown against the damaged stabilizer to illustrate its size against the impact marks. NTSB Image

While a provision in the regulations governing small drone use (14 CFR part 107) does allow for operating them above 400 feet if the drone is within 400 feet of a tall structure, downtown Los Angeles was about ¼ mile away from the collision site.

The regulations also forbid operating drones at night, unless the operator has secured a waiver from the Federal Aviation Administration (FAA) to do so.

The Helinet aircraft was moving between story locations at the time of the collision, and was cruising at between 100 and 110 knots. The pilot told the NTSB he didn’t see anything prior to hearing a loud noise as the object hit the aircraft.

Tests showed traces of a polymer commonly used in drone construction among the damaged areas. NTSB Photo
Tests showed traces of a polymer commonly used in drone construction among the damaged areas. NTSB Photo

The Los Angeles Police Department searched the area around the incident after the helicopter had landed, but couldn’t find a drone.

The object had struck the aircraft’s horizontal stabilizer and tail rotor blade, puncturing and leaving scuff marks along the leading edge of the stabilizer, and leaving a small gouge in the composite surface of one of the tail rotor blades.

The NTSB said laboratory examinations indicated the shape and dimension of the small round dent to the horizontal stabilizer matched the dimensions of “many popular small drones,” and were consistent with a fore-to-aft impact with a “hard cylindrical object.”

An infrared examination also showed traces of a type of plastic that is commonly used in small drones.

One of the aircraft's tail rotor blades suffered gauging in its composite surface. NTSB Photo
One of the aircraft’s tail rotor blades suffered gouging in its composite surface. NTSB Photo

Lab tests that simulated a collision between the horizontal stabilizer and a small drone showed a similar pattern of damage to the stabilizer.

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

In its report, the NTSB noted that it has now completed three investigations where a collision with a drone has been confirmed, and gathered information on two other collisions where the evidence is consistent with a drone strike. As yet, no collisions of this type have resulted in substantial damage or injuries.

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