By Brian Garrett-Glaser

Brian covers the ecosystem emerging around eVTOLs and urban air mobility. Follow him on twitter @bgarrettglaser.


Industry and regulators look to each other for progress, harmonization on eVTOL certification requirements

With numerous eVTOL prototypes regularly flying and the Federal Aviation Administration (FAA) actively working on at least four active type certification applications, disagreements continue to mount between regulators and aircraft developers on how to most effectively ensure a high standard of safety for commercial operations without preventing the air taxi industry from ever leaving the ground.

Volocopter Skyports
Volocopter is one of a few eVTOL ‘trailblazers’ racing to certify the first of a new type of aircraft, with both OEMs and regulators navigating uncharted waters together. Volocopter/Skyports Image

Regulators are moving cautiously, emphasizing a “crawl, walk, run” approach to introducing brand-new technology — powertrains, aircraft, manufacturing techniques, autonomy systems — into the airspace. The FAA, in particular, has the added pressure of the Boeing 737 MAX crisis on it shoulders, which heightened public and congressional attentiveness to issues surrounding aviation certification.

Through the agency’s rewritten Part 23 guidelines for certifying small airplanes, applying performance-based standards rather than prescriptive requirements, the FAA has paved the way for eVTOLs to reach certification — though not yet explicitly permitted it. The European Union Aviation Safety Agency (EASA) has chosen to publish a Special Condition for small-category VTOL aircraft and is finalizing subsequent means of compliance documentation.

Meanwhile, some prominent industry voices continue to pressure FAA and EASA to more rapidly provide guidance to eVTOL developers — and to ensure the two agencies’ approaches are harmonized enough to avoid a market split, where aircraft designed to the standards of one body can’t easily be transferred to the other.

“Every day I’m holding my breath, waiting for the federal register to show the G-1 [certification basis issue paper] for one of the eVTOL developers,” Mark Moore, director of strategy at Uber Elevate, said during the Vertical Flight Society’s Forum 76. “There has been such great work done with [FAA Part 23] Amendment 64 and Part 23 consensus standards, and we’ve got to open up the path clearly and publicly for these aircraft . . . until we see that, the industry will be blocked.”

While individual certification bases contain proprietary information and are not expected to be released publicly, the FAA is expected to publish a policy memorandum that allows eVTOLs with certain characteristics to pursue certification under Part 23 with special conditions, and others — such as multicopters — to be considered more akin to powered-lift aircraft. The FAA did not immediately respond to inquries from regarding upcoming publications.

In response to Moore’s comments, Wes Ryan, unmanned and pilotless aircraft lead at the FAA, made two points: the agency is bound by the proprietary nature of many of the details involved in specific certification projects, and is reticent to publish generic standards until it works through the process for more eVTOL aircraft.

“It’s a great challenge for us to continue [to tackle], but I would also volley it back to you to say, industry has got to keep developing detect-and-avoid technologies, automation technologies, and the electric propulsion and battery technologies to make sure we have viable, flyable products that are safe for civil use,” Ryan said.

That’s a point Reggie Govan, former chief counsel for the FAA, echoed during a recent virtual discussion on the future of drone policy — another new aviation industry struggling to live up to hype around its potential, and often pointing to the speed of regulators as the limiting factor.

“All too often, the default criticism about the pace of the realization of the full benefits of the drone economy have been that the federal regulatory structure is too slow; it’s mired in bureaucracy; if only they would establish the proper regulatory regime, we’d be off to the races,” Govan said, referring to regular approval to fly beyond an operator’s visual line of sight (BVLOS) and in populated areas. “And I think that really oversells the current state of R&D and the very significant work that still needs to be done.”

Most leading eVTOL developers contacted by spoke positively of their relationship with FAA and EASA — unsurprisingly, as they are beholden to the regulators for certification of their aircraft and permission to proceed to commercial operations.

“The pace of regulatory guidance has not hindered Joby,” said Greg Bowles, head of government affairs for Joby Aviation. “The FAA has been working independently with each manufacturer/applicant on means of compliance for their aircraft. The FAA has indicated it wants to get a number of these projects completed before issuing broader regulatory guidance.”

A Volocopter spokesperson similarly told the company “had not felt hindered by regulation in the years that we have worked together with the EASA. Rather, we have felt it is a very fruitful exchange and effective cooperation.”

Mike Whitaker, former deputy administrator of the FAA and now global head of policy for Hyundai UAM, told he sees both sides of the coin.

“I understand the cautious approach of the FAA and its mission to preserve the stellar safety record of our airspace, as well as the frustration of the OEM [original equipment manufacturer] that wants clarity and speed to certification,” Whitaker said. “At the end of the day, neither the regulations nor the technology is quite ready for prime time, and industry and the FAA will need to continue working together to bring this technology and the supporting ecosystem online as fast as can safely be achieved.”

It is easier for Whitaker at Hyundai to acknowledge the inherent frustration in working with safety regulators to introduce entirely new types of aircraft and commercial operations, as Hyundai intends its aircraft to be part of the “second wave” of eVTOLs that achieve certification later this decade.

Investors tell they expect these later entrants to benefit tremendously — saving tens or even hundreds of millions of dollars — from their status as “fast followers,” in part due to technological mistakes and pathfinding by forerunners, but also due to explicit knowledge of general regulatory requirements.

The right approach to safety

EASA, with its proposed SC-VTOL means of compliance already published and more guidance material slated for release in November, has already committed to hold eVTOL aircraft intended for commercial passenger-carrying operations to the same aircraft reliability standards used for commercial airliners: a target level of safety (TLS) of 10-9, meaning that the total probability of a catastrophic failure of an aircraft system is less than one in a billion per flight hour.

EASA’s SC-VTOL includes the above table laying out quantitative safety objectives and functional development assurance levels for small VTOL aircraft. EASA Image

The FAA has not yet decided if it will require that level of reliability from eVTOL aircraft intended to carry passengers. Anything less than 10-9 opens the agency to criticism and increases the odds of a pivotal, industry-defining early crash that damages confidence in the new aircraft type — a top concern of regulators and major OEMs alike.

Uber Elevate’s Mark Moore has repeatedly argued that setting the bar that high for aircraft systems reliability over-emphasizes the occurrence of airworthiness system failures, which represent just 16 percent of Part 135 fatal accidents — as opposed to operational errors, which account for 70 percent. To that end, Uber intends to voluntarily implement a safety management system and recently selected GE Aviation to develop flight data monitoring requirements for its eventual air taxi service.

“The FAA or EASA or any one of these eVTOL developers, they have a constrained amount of resources. That is manpower, experts, money, effort to put into requirements,” Moore said during Forum 76. “With this recognition, the question begs to be asked: where do you put your attention? And in my opinion, these statistics clearly show that it’s in such technologies that can reduce that operator error . . . if we jump to this simple, nice answer of throwing a 10-9 requirement for the design of these eVTOLs, we’re actually going to increase accidents because we’re pushing resources where they are not going to make a difference.”

Mark Moore slide on actual level of safety
Presenting at the Vertical Flight Society’s Forum 76 in October 2020, Mark Moore stressed the importance of targeting operational safety as well as aircraft systems. Mark Moore Image

It is worth noting that the Part 135 failure rates cited by Moore for the most part involve well understood, certified aircraft with long track records; initial models of new aircraft almost always experience more system failures.

But for Uber and OEMs, it’s not just a question of how to best achieve stated safety objectives; there is significant cost to achieving a given reliability standard — a cost that will be passed on to Uber Air passengers and determine the size of the market for the service.

“Our initial estimates show that aircraft amortization and maintenance cost will increase 10 to 25 percent with a 10-9 standard compared to 10-8, and we believe the marginal safety benefits have not been substantiated,” Ryan Naru, regulatory affairs specialist at Uber Elevate, told “Regulatory requirements that do not yield a substantiated safety benefit impact an OEM’s programmatic risk tolerance and willingness to invest in non-mandatory safety technologies.”

Such a requirement is also a way for experienced and well-resourced aerospace manufacturers to increase the barrier-to-entry for competition. Nate Sirirojvisuth, a cost research analyst at PRICE Systems who has worked with Uber and numerous eVTOL developers, told it is “very hard to reach that level of safety from the get-go . . . especially for startups. That [requirement] will be an eliminating factor.”

“It is a significant factor to the cost,” added Anthony DeMarco, president of PRICE. “To meet those higher standards, it could easily increase the cost of a vehicle by anywhere from 25 to 100 percent . . . In our working with different platforms and different reliability and safety standards, we’ve seen those types of cost differences. It could fundamentally change the design.”

The FAA is expected to soon publish special conditions for certification of electric propulsion units (EPUs) and high-voltage architecture, two of the missing pieces of certification material Moore and others are waiting for, while continuing to work individually with eVTOL developers with open certification applications.

For its part, the FAA has repeatedly advised OEMs to engage “early and often” in order to clarify an individual project’s path to certification. But regulatory decisions such as 10-8 or 10-9 TLS for aircraft systems, or design assurance level requirements for avionics software, could set back a development project if announced late into the OEM’s design process. 

“Every aircraft manufacturer needs to establish a certification basis for the aircraft and reach agreement with the authorities on how they plan to show compliance to their certification plan,” Martin Peryea, recently named CEO of Jaunt Air Mobility, told “An OEM cannot start designing an aircraft that they intend to certify and produce without understanding the certification requirements ahead of time. It is very costly to redesign an aircraft late in development.” 

Jaunt, however, is pursuing certification for its single-rotor Journey eVTOL as a traditional rotorcraft under Part 29 with special conditions — and, like Hyundai, is more of a fast-follower than a trailblazer.

And while waiting for regulatory certainty could be a wise approach for OEMs less far along in their design than leaders like Joby Aviation, they may be waiting longer than anticipated and have little influence over general requirements currently being negotiated between regulators and the trailblazers.

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