Joby Aviation, the FAA Type Certificate Race, and the Electric Air Taxi That Is Closer to Your Airport Than Most People Think

Joby Aviation’s S4 electric air taxi is further along in FAA certification than any other eVTOL aircraft currently in development. The company already holds a Part 135 air carrier certificate - the operating authority required to carry passengers for compensation - putting it years ahead of most competitors in the urban air mobility race. With conforming production-representative aircraft flying and more than 30,000 miles of test flights logged, the program has moved well past the concept and prototype phases that define most of its competition.

What Is the Joby S4 and How Does It Work?

The S4 is a purpose-built electric vertical takeoff and landing (eVTOL) aircraft - not a scaled-up drone, not an electrified helicopter. It uses six tilting rotors, three forward and three aft, that point upward for takeoff and landing, then rotate forward as the aircraft accelerates into fixed-wing cruise.

The tilting configuration allows the wings to carry most of the lift in cruise, which is how the S4 reaches speeds approaching 200 mph while keeping battery consumption manageable. Payload is one pilot and four passengers, with a range of approximately 150 miles on a full charge.

The noise signature is the number that drives the entire business case: roughly 45 decibels at 1,500 feet, which Joby compares to a car passing at 15 mph. Six distributed rotors spinning at lower RPM are dramatically quieter than one or two large rotors at high speed. That noise target wasn’t retrofitted - it shaped the fundamental design from the start.

The battery architecture also matters beyond the current numbers. Range and performance figures were achieved with existing lithium-ion technology, meaning they represent a floor. Every improvement in energy density adds range, payload, or reserve margin without requiring an airframe redesign. The S4 was built to absorb better batteries as they arrive.

Why the FAA Certification Path Is Unprecedented

The FAA has certified thousands of aircraft, every one of them built on recognized aerodynamics and proven propulsion with decades of regulatory precedent behind it. The S4 offered none of that. It operates as a rotorcraft for takeoff and landing, transitions to fixed-wing flight, uses six independent electric motor systems, and carries passengers in dense urban airspace - a combination with no existing home in FAA Part 23 or Part 27 regulations.

The FAA’s solution was a G1 issue paper: a negotiated agreement defining specific airworthiness criteria for each novel aspect of the design. Joby received their G1 in 2021, establishing a fixed certification basis rather than an open-ended moving target. That commitment - to a defined rulebook - is more significant than most coverage reflects.

The redundancy philosophy built into the power system is part of what the G1 had to address. No single cell failure cascades. Six independent motor systems mean multiple failures have to stack before the aircraft faces a serious situation. That is not trivial to engineer, and it is not trivial to certify.

Where Joby Stands in the Five-Stage Certification Process

The FAA’s certification path for the S4 has five distinct stages:

Stage 1 - Define airworthiness criteria. Completed with the G1 in 2021.
Stage 2 - Initial FAA design approval. Completed in 2022.
Stage 3 - Flight test evidence.
Stage 4 - Conforming production-representative aircraft. Current stage.
Stage 5 - Final review and type certificate issuance.

Stage 4 is the critical distinction from what most competitors are doing. Conforming aircraft means machines built the way the production line will build them - not hand-built prototypes that prove a concept. The aerodynamic data coming off these flights represents actual production performance, not development-aircraft approximations.

In 2023, the FAA issued Joby a Part 135 air carrier certificate, the same operating authority a charter airline holds. To issue that certificate, the FAA already evaluated Joby’s maintenance procedures, pilot training framework, and safety management systems. When the type certificate arrives, Joby does not build an airline from scratch - the operational infrastructure is already certified.

The Institutional Backing Behind the Program

Toyota has invested more than $400 million in Joby. Delta Air Lines committed $200 million and structured a partnership to integrate S4 service into Delta’s travel ecosystem at major airports. The Department of Defense has awarded Joby contracts for military applications of the aircraft, which also funds accelerated flight testing and manufacturing development.

In 2020, Joby acquired Uber Elevate, the ride-hailing company’s air mobility division, bringing engineering talent, market research, and relationships with city governments that had been studying urban air mobility infrastructure for years.

Joby’s manufacturing facility in Marina, California is being built for scale production. A program that can build one aircraft per year is a research project. A program that can build hundreds per year is an airline supplier. Joby is building for the latter.

How the Competition Compares

Archer Aviation is probably the closest competitor in certification progress. Archer’s Midnight aircraft is also in FAA certification, with United Airlines as a launch customer. The configuration differs from the S4, but the mission profile is similar: short urban corridors, quiet operation.

Wisk Aero, backed by Boeing, is pursuing full autonomy - no pilot required. That is not a near-term certification path. The FAA is not currently positioned to certify pilotless passenger aircraft, and Wisk is building toward a regulatory framework that does not yet fully exist.

Supernal, Hyundai’s eVTOL subsidiary, is at an earlier stage with the S-A2 aircraft. The resources behind that program are substantial, but resources do not compress the FAA certification timeline.

Lilium, the German company using electric ducted fans, went through bankruptcy in 2024 and has been revived under new ownership. The technical approach is sound; the energy economics per passenger mile are still being validated.

The Infrastructure Problem No Aircraft Solves Alone

The aircraft certification is arguably the easier half of the problem. Several parallel challenges have to resolve before any eVTOL service operates at meaningful scale.

Vertiports have to be built and permitted at urban locations that were never designed for aviation. Air traffic control procedures for low-altitude urban corridors do not yet exist - the National Airspace System was not designed for hundreds of electric aircraft flying short hops between rooftops in dense metro areas. Battery charging infrastructure at every landing site places serious electrical grid demands on buildings that have no aviation load history. Pilot type ratings for the S4 require simulators that have to be built, certified, and operated before the first revenue flight.

None of these are unsolvable. They are being solved in parallel with aircraft certification, on different timelines, by different organizations under different regulatory frameworks. When the type certificate arrives, Joby will not immediately be flying everywhere. A ramp-up period, likely measured in years, follows while infrastructure catches up to the hardware.

When Commercial Service Is Realistic

Joby has publicly stated a commercial service target of 2025. That date has slipped before and may slip again - type certificate programs consistently run longer than projected, and the S4 is being certified under criteria with no historical baseline for duration.

The more credible near-term scenario, based on current Stage 4 status, is limited commercial operations beginning in a specific geography - likely a market such as New York or Los Angeles with Delta integration - in the 2026 to 2027 timeframe. Broader expansion follows as vertiport infrastructure develops behind the initial routes.

Why This Matters for Pilots Who Will Never Fly an S4

The certification frameworks being built for the S4 are the foundation of electric aviation regulation. The G1 issue paper structure that Joby negotiated is already being applied by other manufacturers across the industry. The distributed electric propulsion failure analysis methodologies that Joby and the FAA developed together are becoming the standard approach for certifying any multi-rotor electric aircraft.

When the first commercial turbine aircraft went through FAA certification in the early 1950s, engineers created frameworks that governed jet aviation for the next several decades. Joby’s Stage 4 reviews are doing the same thing for electric aviation right now. The rules being written in these reviews will shape what is technically permitted - and what is prohibited - for a very long time. Whether you ever step into an S4 or not, those rules will define the next generation of aircraft you do fly.

Key Takeaways

Joby’s S4 is in FAA Stage 4 certification with conforming production-representative aircraft flying and more than 30,000 miles of total test flight hours completed.
Joby holds a Part 135 air carrier certificate (issued 2023), meaning maintenance, pilot training, and safety management systems are already FAA-approved - not pending.
The G1 issue paper, negotiated in 2021, locks in a defined certification basis. The FAA committed to a fixed rulebook, not an open-ended target.
Commercial service is realistically projected for 2026–2027 on initial limited routes, with broader expansion dependent on vertiport and charging infrastructure buildout.
The certification precedents Joby is establishing with the FAA will define the regulatory framework for all electric aviation that follows - including aircraft currently flying today.