The eVTOL Certification Marathon: How the Class of 2025 Is Actually Progressing
In 2021 and 2022, a wave of investor decks and press releases confidently projected that urban air mobility would be carrying paying passengers by 2024. Some named specific cities. Some named specific launch partners. A few named specific ticket prices.
It is now mid-2026, and nobody is flying fare-paying passengers in a certified eVTOL aircraft anywhere in the world. The question worth asking — not rhetorically, but operationally — is why, and more importantly, what the realistic path forward actually looks like for the programs that are still standing.
This is not a story about failure. The engineering being done by the leading eVTOL programs is genuinely difficult, genuinely novel, and in several cases genuinely impressive. But the certification process has exposed a structural mismatch between how aerospace startups communicate externally and how aviation regulators actually work. Understanding that mismatch is the only way to form an accurate picture of what happens next.
Where the Leading Programs Actually Stand
Joby Aviation
Joby is the most advanced eVTOL program in the United States by most credible measures. The company has flown its S4 prototype more than 1,000 times, holds a Part 135 Air Carrier Certificate (a meaningful operational credential, not a certification shortcut), and has a signed agreement with the U.S. Air Force under AFWERX that has accelerated some testing timelines.
As of mid-2026, Joby is in Stage 4 of the FAA’s five-stage type certification process — the compliance demonstration stage. This is where the actual test evidence gets submitted and reviewed against agreed means of compliance. Stage 4 is not a formality. It is where programs that believed they had solved their compliance challenges discover that the FAA’s interpretation of acceptable evidence does not always match the applicant’s interpretation.
Joby’s primary open items involve flight control system software, the propulsion system’s interaction with the airframe under failure modes, and battery thermal management under sustained high-power conditions. None of these are unsolvable. All of them require time and test data.
Realistic type certificate: late 2027, with commercial service in 2028 or 2029.
Archer Aviation
Archer’s Midnight aircraft is a lift-plus-cruise design — a configuration that, from a certification standpoint, is somewhat more tractable than a full tilting-rotor design like Joby’s S4, because the flight envelopes for the lift rotors and the cruise propeller are more clearly separable. This is a real advantage in means of compliance negotiations because it reduces the surface area of novel compliance arguments.
Archer completed its first transition flight test in late 2023 and has been accumulating flight test data since. The company is working through Stage 3 (compliance planning) and early Stage 4 work, with an emphasis on getting the software certification artifacts aligned with FAA expectations before generating the bulk of flight test data.
That sequencing decision — software compliance path first, test execution second — reflects a lesson the industry learned the hard way: generating thousands of hours of flight test data against a software certification basis that FAA subsequently disputes is extraordinarily expensive. Archer appears to have internalized this lesson better than some competitors.
Archer also has a United Airlines partnership that creates commercial pressure but not regulatory pressure. The FAA does not accelerate type certification because an airline wants to fly the aircraft.
Realistic type certificate: 2027–2028.
Lilium’s Successor Programs
The original Lilium GmbH entered insolvency in October 2023. The jet-vectored-thrust design was technically ambitious — arguably too ambitious for a first-generation certification campaign — and the company ran out of runway before it ran out of engineering problems.
What emerged from the wreckage is more complex. Lilium GmbH was acquired by a consortium and relaunched as Lilium eAircraft in early 2024, operating primarily under EASA jurisdiction with Germany as the state of design. A separate U.S.-focused entity, Lilium Inc., was assembled around some of the original IP and team members.
The EASA certification path is in some respects more structured than the FAA path — EASA’s SC-VTOL special condition framework provided earlier regulatory clarity — but the jet-based propulsion concept faces genuinely novel certification challenges that the rotor-based designs do not. Specifically, the lack of autorotation or graceful rotor degradation capability means the failure mode analysis for propulsion system faults is handled almost entirely through redundancy architecture, and demonstrating that redundancy architecture to EASA’s satisfaction requires a specific test program.
As of mid-2026, Lilium eAircraft is conducting ground testing in Germany and has not yet resumed crewed flight operations with the new organization. The timeline for any commercial operation is realistically 2029 at the earliest.
Wisk Aero
Wisk is worth separate treatment because its strategy is structurally different from every other program discussed here. Wisk is pursuing a fully autonomous (no pilot) eVTOL — the Cora and now the Generation 6 design — which means its certification campaign has to solve a problem that the other programs can defer: what is the regulatory basis for an aircraft that carries passengers but has no onboard pilot?
The FAA has no established type certification pathway for passenger-carrying autonomous aircraft. There is AC 20-178, there is ASTM F3269 for means of compliance for highly automated systems, and there is ongoing FAA rulemaking, but there is no approved special condition specifically for autonomous passenger operations under Part 135 or Part 23.
Wisk’s near-term strategy appears to involve initial operations with a remote pilot-in-command, accumulating safety data, and using that operational data to support eventual fully autonomous certification. This is a credible long-term strategy and a significant short-term constraint.
Realistic commercial operations: 2028 with remote PIC, fully autonomous in the 2030s.
Overair’s Legacy
Overair ceased operations in January 2024, unable to secure additional funding. The Butterfly aircraft — a quadrotor tiltrotor design — had completed early-stage hover testing but was far from flight test maturity. The engineering team dispersed across the industry, and the IP was acquired by parties who have not announced plans to continue development.
Overair’s failure is instructive primarily because it illustrates the funding cliff problem that is distinct from the certification problem. The company did not fail because FAA certification was too hard. It failed because the capital required to get from early prototype to type certification is measured in hundreds of millions of dollars, and the investors who funded the early stages were not prepared to sustain the certification marathon.
The Real Bottlenecks
Means of Compliance Negotiation
Every eVTOL program is certifying under some combination of FAA Special Conditions, EASA SC-VTOL, and either Part 23 or Part 27 as the base certification basis. None of these frameworks were written with distributed electric propulsion in mind. This means that for a large fraction of the aircraft’s novel features, the applicant and the regulator have to negotiate what evidence will constitute acceptable compliance demonstration.
This negotiation is not adversarial — it is collaborative — but it is slow. The FAA has limited bandwidth of engineers who understand both distributed electric propulsion and certification methodology. When an FAA Aircraft Certification Office has a novel compliance question that requires new engineering guidance, it goes through an internal review process that can take six to eighteen months.
The programs that have made the most progress in means of compliance negotiations are the ones that arrived at the table with fully developed compliance arguments — not just the aircraft design, but the logical chain from regulatory requirement to design feature to test evidence. This requires treating requirements as traceable engineering artifacts from the beginning of the program, not assembling a compliance argument retroactively.
Software Certification Under DO-178C
The flight control software for a distributed electric propulsion aircraft is among the most complex software ever submitted for aerospace certification. A typical eVTOL with six to twelve independently controlled rotors requires a flight control law that handles propulsion system failures, asymmetric thrust conditions, and degraded-mode operations across a flight envelope that transitions between hover and forward flight.
DO-178C, the software development standard for airborne systems, requires rigorous documentation of software requirements, architecture, code, and verification — at a level of detail that most software engineers outside aerospace find extraordinary. For a novel aircraft, the additional challenge is that the software requirements derive from the aircraft-level safety requirements, which themselves depend on the means of compliance that the FAA has accepted. If the means of compliance changes, the software requirements may change, and the DO-178C artifacts have to be updated accordingly.
This dependency chain is why software certification is the longest pole in the tent for every program. It is not that the software is badly written. It is that the certification artifacts for complex, novel software take years to produce and verify.
Battery Certification
The FAA issued Special Conditions for lithium battery propulsion systems — the first for a transport-category-adjacent eVTOL application — that require applicants to demonstrate cell-level, module-level, and pack-level safety across a range of abuse conditions including thermal runaway, external short circuit, overcharge, and crash load scenarios.
The challenge is not that the batteries are unsafe. Modern lithium battery technology is well understood. The challenge is that generating the test data required by the special conditions takes time that cannot be compressed. Cell aging under realistic charge-discharge cycles requires months of testing. Pack-level thermal propagation testing requires building production-representative packs, which requires the manufacturing process to be sufficiently mature. The certification evidence and the manufacturing readiness are coupled in ways that most programs underestimated.
Human Factors
For the piloted programs — Joby, Archer, Lilium — the cockpit design and crew training curriculum require human factors certification that, for a novel aircraft type, is anything but routine. The FAA’s human factors guidance in AC 25.1302-1 was written for fixed-wing transport aircraft. Applying it to an aircraft that spends meaningful time in hover, transitions between flight modes, and relies on fly-by-wire for all normal operations requires applicant-specific means of compliance that the FAA must review and approve.
The specific open items across programs include failure annunciation design (how does the pilot know which of twelve rotors has failed, and what action is required?), mode awareness (what flight mode is the aircraft in, and what is it about to do?), and training syllabus minimum hour requirements for a type rating on a novel aircraft category.
Why 2024 Slipped — and What 2027 Actually Requires
The 2024 entry-into-service projections were based on an optimistic reading of two things: FAA certification speed and technology readiness. Both were wrong, but in different ways.
The FAA speed assumption was wrong because it treated certification as a document-review process rather than a physics-verification process. Regulators need to be convinced that the aircraft is safe, not just that the paperwork says it is safe. That takes time proportional to how novel the aircraft is.
The technology readiness assumption was wrong because several programs began their certification campaigns before their designs were stable. When the aircraft design changes during certification — because testing reveals a needed modification — the compliance argument has to be rebuilt from that change point forward. Programs that changed their designs significantly after beginning the formal certification process have paid for those changes in years, not months.
The programs that will reach type certification in 2027–2028 are the ones that have maintained design stability since approximately 2023, have DO-178C artifacts that are ahead of (not behind) their flight test programs, and have FAA agreement on means of compliance for all major novel features. That description fits Joby most closely, Archer second.
Modern requirements management tooling has played a measurable role in the programs making the most progress. Maintaining live traceability between aircraft-level safety requirements, system requirements, software requirements, means of compliance commitments, and test evidence — across a program with hundreds of engineers and thousands of requirements — is a systems engineering problem as much as it is an engineering problem. Tools like Flow Engineering, which are built around graph-based requirements models rather than document-based RTMs, allow certification teams to answer the question “if this means of compliance changes, what else changes?” in hours rather than weeks. For a certification campaign where FAA feedback can arrive at any time, that kind of responsive traceability is not a nice-to-have.
Honest Assessment
The eVTOL class of 2025 — the programs that expected to be flying passengers by now — is not failing. It is maturing, more slowly than the market expected and more realistically than the original projections allowed.
Joby and Archer are the most likely candidates for type certification in the 2027–2028 window. Wisk will follow with a constrained operational model. The Lilium successor programs face the longest road. Overair’s design is, for practical purposes, discontinued.
The honest summary is that novel aircraft certification takes about as long as it takes. The physics, the software, and the regulatory process do not compress on investor timelines. The programs that understood this earliest, and built their engineering processes accordingly, will be first to market. The programs that believed the optimistic projections and staffed and funded accordingly have already paid the price.
The urban air mobility market is real. The technology is real. The certification path is navigable. It just takes longer than anyone wanted to admit in 2021.