Joby Aviation says it has begun routine piloted transitions between vertical and cruise flight during flight testing of its S4 tiltprop electric air taxi.
The achievement keeps the company on track to begin flight tests in Dubai this summer and start certification testing with the FAA early in 2026.
Piloted transition between thrustborne vertical and wingborne horizontal flight is a key milestone for electric vertical-takeoff-and-landing (eVTOL) aircraft developers. Previously, only Beta Technologies had flown piloted transitions with a full-scale winged eVTOL prototype, which it first achieved in April 2024.
Joby completed its landmark flight on April 22 with chief test pilot James “Buddy” Denham flying the fourth and latest aircraft to roll off the production line in Marina, California, registered N544JX. The company has since completed multiple transition flights with three different pilots at the controls.
The startup says it is the first eVTOL developer to routinely perform crewed testing from hover to wingborne flight. Both EHang and Volocopter are routinely flying crewed, but their multicopter eVTOLs operate in thrustborne mode only and do not transition to wingborne cruise flight.
Joby conducted the first uncrewed transition of a full-scale prototype in 2017 and completed hundreds of remotely piloted transitions before the milestone piloted flight.
“This was planned all along, to be able to get to this point of the program in a very methodical way that tangibly moves us closer to type certification,” says Didier Papadopolous, Joby’s president of aircraft OEM. “This is not a demonstration—I want to be clear about that. This is a step into a new phase of our active flight test program.”
Getting to the piloted transition involved breaking the aircraft down to its constituent parts and developing a design, build and test program to achieve the confidence level required to put a pilot on board and fly through the complete flight envelope from hover to cruise and back.
“We tested every piece of equipment all the way to the aircraft in normal conditions, and then we tested it in abnormal conditions, or failure cases,” Papadopolous says. “A few weeks ago, in the Integrated Test Lab, we started injecting failures, failing propulsion units, actuators and seeing how the aircraft continues to operate.
“When this was a success, we took it to the aircraft and we flew in a remote piloted configuration,” he says. This testing was conducted at Edwards AFB, California. “We would turn off a propulsion unit, a second propulsion unit or a full battery pack and would ensure that the aircraft continues to fly safely and land at a destination on purpose.”
The remote testing at Edwards was the “last unlock” for piloted transition, Papadopolous says. Injecting failures of propulsion units, batteries, actuators and other systems in the full range of flight phases from hover through semi-thrustborne flight to wingborne cruise “was the key unlock for this next phase.”
At the same time, all the test plans, build methodologies and procedures were the same as Joby plans to use when it receives type inspection authorization from the FAA and begins flight testing for certification credit. “It’s a double win,” Papadopolous says.
Joby currently has four active test aircraft, each assigned to specific types of testing, such as loads and flutter. “We have multiple airplanes that are capable of both remote flying and piloted flying through full transition,” Papadopolous says. “We’ll continue to use that mix because it is more efficient.”
With routine pilot transition capability, Joby will start looking at different aspects of the aircraft. “We’re now talking about what the passenger comfort and the acoustics look like,” he says. In addition to the pilot, Joby plans to begin carrying flight-test engineers on the aircraft.
Piloted transition is also critical to plans to begin experimental flights in Dubai this summer ahead of launching commercial air taxi service in the emirate, which is targeted for 2026.
Joby plans for all flight tests in Dubai to be piloted, says chief product officer Eric Allison, as it is easier to gain approval for crewed versus uncrewed flying. “If you go in remote, then you have to worry about your spectrum approvals and the complexities on that front,” he says.
“We’ve unlocked the ability to deliver on the Dubai mission,” Papadopolous adds. “All of the missions we will be doing in Dubai, we are doing here first. We’ve finished a good chunk of them already, including on the same airplane that will be operating in Dubai.”