US safety board seeks input to proposed removal of weight threshold for UAS accident reporting

The National Transportation Safety Board (NTSB) proposes amending the definition of “Unmanned aircraft accident” by removing the weight-based requirement and replacing it with an airworthiness certificate or airworthiness approval requirement. The weight threshold is no longer an appropriate criterion because unmanned aircraft systems (UAS) under 300 lbs. are operating in high-risk environments, such as beyond line-of-sight and over-populated areas. The proposed definition will allow the NTSB to be notified of and quickly respond to UAS events with safety significance.

Responses are invited by 20 July 2021.

According to the NTSB, the proposed definition will only affect those operations under 14 CFR part 107 that apply to small UAS that weigh less than 55 lbs. and hold an airworthiness certificate. It will not affect hobbyist/modeler operations. The NTSB does not intend to investigate such accidents.

As the FAA moves towards airworthiness certification for drones, the NTSB wants to replace the weight-based definition, instead referring to unmanned aircraft with an airworthiness certificate or airworthiness requirement, says Drone Life.

The NTSB prescribes regulations governing the notification and reporting of accidents involving civil aircraft. As an independent federal agency charged with investigating and establishing the facts, circumstances, and probable cause of every civil aviation accident in the United States, the NTSB has an interest in redefining a UAS accident in light of recent developments in the industry.

For NTSB purposes, “unmanned aircraft accident” means an occurrence associated with the operation of an unmanned aircraft that takes place between the time that the system is activated with the purpose of flight and the time that the system is deactivated at the conclusion of its mission, and in which any person suffers death or serious injury, or in which the aircraft has a maximum gross takeoff weight of 300 lbs. or greater and receives substantial damage.

At the time this definition was contemplated, the weight-based requirement was necessary because defining an accident solely on “substantial damage” would have required investigations of numerous small UAS crashes with no significant safety issues. See Final Rule, 75 FR 51953, 51954 (Aug. 24, 2010). Consequently, there is no legal requirement to report or for the NTSB to investigate events involving substantial damage to UAS weighing less than 300 lbs. because these are not recognized “unmanned aircraft accidents” under the NTSB’s regulations. While this definition ensured that the NTSB expended resources on UAS events involving the most significant risk to public safety, the advent of higher capability UAS applications—such as commercial drone delivery flights operating in a higher risk environment (e.g., populated areas, beyond line-of-sight operations, etc.)—has prompted the agency to propose an updated definition of “unmanned aircraft accident.” Moreover, in the August 24, 2010, Final Rule, the NTSB anticipated future updates of the definition given the evolving nature of UAS technology and operations.

he NTSB believes that an updated definition is necessary given the changing UAS industry. Pursuant to section 44807 of the Federal Aviation Administration (FAA) Reauthorization Act of 2018 (Reauthorization Act), the FAA has recently promulgated proposed rulemaking regarding UAS. Section 44807 directed the Department of Transportation to use a risk-based approach to determine if certain UAS may operate safely in the national airspace. A number of drone delivery operations, among other applications, have begun using: (1) FAA Special Airworthiness Certificates—Experimental, or (2) approvals under the exemption processes per section 44807 of the Reauthorization Act that allows the FAA to grant exemptions on an individual basis. As drone delivery and other applications develop, airworthiness certification will become more prevalent for certain unmanned aircraft similar to that of manned aircraft.

Therefore, an unmanned aircraft—of any size or weight—used for certain activities will require airworthiness certification or approvals due to higher risk potential, such as flights over populated areas for deliveries. Moreover, a substantially-damaged delivery drone may uncover significant safety issues, the investigation of which may enhance aviation safety through the independent and established NTSB process. This proposed definition change will treat a UAS with airworthiness certification or airworthiness approval in the same manner as a manned aircraft with airworthiness certification or airworthiness approval, thereby enabling the NTSB to immediately investigate, influence corrective actions, and propose safety recommendations.

Accordingly, the proposed definition will be flexible to account for changes in the UAS industry and will allow the NTSB to respond quickly to UAS events with safety significance, while not burdening the agency or public with unnecessary responses.

Deadline for comments: 20 July 2021

NTSB docket number: 2021-0004

e-Rulemaking portal:


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