Drone / Helicopter Mid Air Collision Over Los Angeles City Hall ‘Probable’ Said NTSB (Airbus AS30B2 N71HD)
July 6, 2020
The U.S. National Transportation Safety Board (NTSB) explain in their safety investigation report (issued June 29 2020) that the pilot, “… reported colliding with an unknown object at 1,100 feet above mean sea level (msl) in the vicinity of Los Angeles City Hall. The pilot conducted a precautionary landing at a nearby helipad. Post-flight examination revealed minor damage to the right horizontal stabilizer and tail rotor blade.”
The helicopter was equipped with a SpiderTrax [sic] flight following system, which indicated the helicopter passing northeasterly in the vicinity of LA City Hall at 7:15 p.m. at 1,104 feet msl (approximately 828 above ground level (agl)).
The three occupants were uninjured.
There was a small round dent which partially punctured the leading edge of the horizontal stabilizer. Further dents and scuff marks were approximately 6 to 8 inches outboard of the round dent on the leading edge and along the upper surface. One of the tail rotor blades exhibited a small gouge in the composite surface approximately midchord. The horizontal stabilizer and tail rotor were sent to the NTSB Materials Laboratory for examination. Visual examination was consistent with an inflight hard-body impact. The dent and scuff marks were compared to the dimensions of common small drones and were consistent with the distance and orientation between the motor and center fuselage/battery compartment.
These peaks were consistent with a polycarbonate polymer. Examination of an exemplar popular drone indicated the primary construction material is polycarbonate. (Polycarbonate plastics are used in many other common items, such as safety glasses or light lenses). Under magnification, inside the round dent, a small circular indentation was noted of approximately 0.125 inches (~3 mm) in diameter, exhibiting tears and cracking around its circumference.
No evidence was found of a missing drone however, the operator reported that the onboard cameras were stowed and did not record video at the time of the reported collision. The operator and NTSB investigator conducted a search of social media for any possible indications of a lost drone in the area, nothing definitive was found. Two drone detection companies were operating in the area but did not have any targets in the area at the time of the report. Both companies reported less than complete coverage of the area.