On 14 December 2017 the National Transportation Safety Board determined the operator of a drone that collided with an U.S. Army helicopter failed to see and avoid the helicopter because he was intentionally flying the drone out of visual range and did not have adequate knowledge of regulations and safe operating practices.
The incident took place near Hoffman Island, New York, 21 September 21, 2017, when a DJI Phantom 4 small unmanned aircraft system and a U.S. Army Sikorsky UH-60M Black Hawk helicopter collided at an altitude of about 300 feet. The helicopter landed safely; the drone was destroyed. A 1 1/2 – inch dent was found on the leading edge of one of the helicopter’s four main rotor blades and parts of the drone were found lodged in the helicopter’s engine oil cooler fan.
The drone operator was unaware of the collision until an NTSB investigator contacted him. The operator was also not aware of temporary flight restrictions that were in place at the time because of presidential travel and a United Nations General Assembly session. He was flying recreationally and did not hold an FAA remote pilot certificate.
The full investigative report is available online at https://go.usa.gov/xnnkh.
According to the NTSB:
“The United States Army UH-60M helicopter was operating under visual flight rules within Class G airspace about 300 ft above mean sea level (msl) when it collided with a privately owned and operated DJI Phantom 4 small unmanned aircraft system (sUAS). The helicopter sustained minor damage and landed uneventfully; the sUAS was destroyed. Although the pilot flying the helicopter saw the sUAS before impact and immediately applied flight control inputs, there was insufficient time to avoid the collision.
“The sUAS pilot was operating the aircraft recreationally and did not hold a Federal Aviation Administration (FAA) Remote Pilot certificate. Hobby and recreational pilots are expected to operate their aircraft in accordance with Title 14 Code of Federal Regulations Part 101, which includes maintaining visual contact with the aircraft at all times and not interfering with any manned aircraft. There are no training or certification requirements for model aircraft pilots.
“During the incident flight, the pilot of the sUAS intentionally flew the aircraft 2.5 miles away, well beyond visual line of sight and was just referencing the map on his tablet; therefore, he was not aware that the helicopter was in close proximity to the sUAS. Although the pilot stated that he knew that the sUAS should be operated at an altitude below 400 ft, flight logs revealed that he had conducted a flight earlier on the evening of the incident, in which he exceeded 547 ft altitude at a distance of 1.8 miles, which was unlikely to be within visual line of sight. In addition, even though the sUAS pilot indicated that he knew there were frequently helicopters in the area, he still elected to fly his sUAS beyond visual line of sight, demonstrating his lack of understanding of the potential hazard of collision with other aircraft. In his interview, the sUAS pilot indicated that he was not concerned with flying beyond visual line of sight, and he expressed only a general cursory awareness of regulations and good operating practices.
“A Temporary Flight Restriction (TFR) was in effect for the area of the flight; the helicopter was authorized for flight within this area. The helicopter was operating over water and not in the vicinity of any vessels; therefore, its operating altitude was in accordance with FAA regulations and Army guidance. The sUAS pilot was unaware of the active TFRs in the area that specifically prohibited both model aircraft and UAS flight. Further, the sUAS pilot relied only on the DJI GO4 app for airspace awareness. Although the TFR airspace awareness functionality in the DJI app (GEO) was not active at the time of the incident, this feature is intended for advisory use only, and sUAS pilots are responsible at all times to comply with FAA airspace restrictions. Sole reliance on advisory functions of a non-certified app is not sufficient to ensure that correct airspace information is obtained. Had the functionality been active, the sUAS pilot would still have needed to connect his tablet to the internet before the flight in order to receive the TFR information. Since the sUAS pilot’s tablet did not have cellular connection capability, it is unlikely that he would have been able to obtain TFR information at the time of the flight. Because the pilot solely relied on the app to provide airspace restriction information; he was unaware of other, more reliable methods to maintain awareness.
“The collision occurred 2 minutes before the end of civil twilight. Although modeler (recreational) sUAS pilots may fly at night under certain conditions, when asked about night flight, the incident pilot only stated that he had built-in position lights; thus he was likely unaware of any guidelines or practices for night operations.
“There was no evidence of any mechanical or software problems with the sUAS relevant to the flight. The pilot did not report any anomalies, and stated the recorded information on the flight logs accurately reflected the incident flight. The sUAS operated as expected at all times. Although the recorded data showed a 9-second gap in telemetry, this was likely due to distance from the remote controller.
“The National Transportation Safety Board determines the probable cause(s) of this incident to be:
the failure of the sUAS pilot to see and avoid the helicopter due to his intentional flight beyond visual line of sight. Contributing to the incident was the sUAS pilot’s incomplete knowledge of the regulations and safe operating practices.”