Dollars or pounds, what should trigger a drone accident investigation?

Comments closed this week on a notice o f proposed rulemaking put forth by the National Transportation Safety Board, the government agency responsible for investigating transportation accidents, on the definition of drones and how that definition should be used to trigger accident investigations.

Only two submitted comments were posted to the official docket, but both are in agreement that NTSB should be able to expand its authority to investigate drone accidents – with some conditions. Currently, the NTSB is authorized to investigate any accident involving a drone when that drone has a gross takeoff weight of more than 300 pounds.

Both the Small UAV Coalition and the Association for Unmanned Vehicle Systems International (AUVSI) are in favor of changing the accident investigation threshold from strictly a weight-based trigger to one that incorporates a damage threshold.

“AUVSI welcomes fact-based investigations from the NTSB into UAS (unmanned aircraft systems) accidents,” AUVSI wrote in its comments. “In the extremely rare instances where drones have been involved in incidents, media sensationalism and the resulting social anxiety have worked against the UAS industry.”

Finding a new trigger

In the notice, NTSB said the current weight threshold was no longer appropriate.

“The weight threshold is no longer an appropriate criterion because … 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,” the notice stated.

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The agency seeks to alter its definition of unmanned aircraft, noting that at the time the definition was created in 2010, “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.”

The result is that there is no legal requirement to report a drone accident when the drone weighs less than 300 pounds. With the expansion of drone deliveries and more drone operators being given Federal Aviation Authority approval to fly over people and buildings, NTSB is concerned that accidents could go unreported.

Aligning with FAA

NTSB wants to move to an airworthiness certification as awarded to operators by the FAA as a standard.

“As drone delivery and other applications develop, airworthiness certification will become more prevalent for certain unmanned aircraft similar to that of manned aircraft,” NTSB said.

The agency, which has authority to investigate manned aircraft accidents, is looking for the same authority for drones, regardless of size or weight.

“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,” the agency said. “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.”

Both AUVSI and the Small UAV Coalition agree with NTSB, to an extent. The groups’ comments indicate concern that NTSB may be overreaching with the authority request to investigate all UAS with airworthiness certification or a “substantially damaged delivery drone.”

Instead, the groups argued NTSB should adopt a $500 property-damage limit excluding the drone itself. AUVSI also proposed NTSB maintain a weight-based criteria but tie it to FAA’s current “substantial damage” clause within that agency’s definition of “small unmanned aircraft system category,” which is UAS of less than 55 pounds.

Damage trigger

AUVSI also said NTSB should align its language with the FAA’s Part 107 rule (14 CFR 107) accident reporting language.

“Specifically, we propose the condition to specify that these accident investigations are only undertaken if the cost of repairs exceeds $500 and/or the fair market value of property damage exceeds $500, as is the case in the Accident Reporting clause of §107.9. This will ensure that the NTSB’s authority is targeted in a cost-effective manner that yields true benefits to aviation safety,” AUVSI said in its comments.

The Small UAV Coalition agreed in its comments, also noting concern over NTSB’s proposal of substantial damage triggering an investigation impacting drone operators that build in redundancies to purposely damage the drone when that is the lesser of two evils.

“The coalition agrees with the FAA’s example of a remote pilot who decides to crash the drone to avoid the risk of collision with a person or property. Even if the board does not agree to revise its focus from the aircraft to property other than the aircraft, drones that are crashed intentionally by the operator should not be reportable,” it said.

AUVSI noted that many drones are designed to deploy a parachute or otherwise crash themselves when a malfunction or weather conditions necessitate action to protect people and property.

“These and many other types of risk mitigations are built into UAS that are receiving an airworthiness certification. Therefore, clarification that an accident investigation is not required when the UAS acts as intended as defined by the airworthiness certificate or approval, even if damage is incurred, would be appropriate,” AUVSI said.

Unnecessary investigations

“The proposed revised definition would result in required investigations for events that incur no measurable impact upon property. This would needlessly waste the time and resources of both the UAS operator and the government and has the potential to substantially impact the financial viability of commercial drone operations,” the Small UAV Coalition said in its comments.

The groups said NTSB should adopt current FAA rules, which exclude investigations of air accidents when less than $500 of property damage occurs.

“While the NTSB proposal does not address FAA investigations of unmanned aircraft accidents, the coalition recommends the NTSB and FAA agree on criteria to determine whether the NTSB or FAA should be the lead agency of an UAS accident investigation, consistent with FAA Order 8020.11D,” the Small UAV Coalition said. “In sum, the coalition seeks a revision to the definition of ‘substantial damage’ to related to property other than the drone; and a revision to the proposed language to exclude experimental category aircraft; and a clarification that the NTSB’s use of the term ‘airworthiness approvals’ means exemptions under section 44807.”

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