Vertical Aerospace, a global aerospace and technology company that is pioneering electric aviation, today announced it has received its Permit to Fly from the UK Civil Aviation Authority (CAA) and commenced ‘Phase 4 – Transition’ flight testing, the final stage of its VX4 prototype flight-test programme.

This regulatory approval enables Vertical’s flight-test team to begin testing the VX4 prototype’s defining transition manoeuvre - seamlessly shifting between hover (“helicopter mode”) and wingborne flight (“airplane mode”).

Vertical’s Test Pilot, Paul Stone, flew the first flight of this phase at 10:11am GMT on 13 November 2025.

‘Phase 4 – Transition’ represents the final stage of the VX4 prototype flight test programme and follows completion of Phases 1-3, earlier in the year. These confirmed the VX4’s exceptional flying qualities and included flying in open airspace for the first time.

To prepare for piloted transition flight, Vertical’s engineering and test teams recently completed extensive simulation, ground, and flight testing in collaboration with the UK CAA, verifying all 200 Minimum Safe Aircraft requirements.

In support of our Permit to Fly, more than 20,000 pages of safety and technical information were updated and submitted to the CAA. The CAA is working closely with the European Union Aviation Safety Agency (EASA) on the certification and concurrent validation of the VX4 to the highest global safety standards required for commercial use.

Stuart Simpson, CEO, Vertical Aerospace, said: “Receiving our Permit to Fly and starting Phase 4 marks a defining moment for Vertical Aerospace. Our team has spent months verifying every core system under close regulatory oversight, reflecting our unique and robust approach to certification. Phase 4 is a critical demonstration of the VX4’s unique tiltrotor capability and a major technical and certification unlock.”

Last week, as part of its Q3 Business & Strategy update call, Vertical shared an animation explaining this critical step of transition and a first look at its new certification aircraft's leading cabin size and comfort.

Vertical’s piloted flight test programme explainer:

- Phase 1: Tethered: the VX4 prototype will perform stabilised hover while loosely tethered to the ground. Complete: 12 September 2024.

- Phase 2: Thrustborne: the VX4 prototype will take-off and land vertically and conduct low speed flight manoeuvres with lift generated by the propellers. Complete: 4 February 2025.

- Phase 3: Wingborne: the VX4 prototype will take-off, fly and land like a conventional aircraft, with lift generated by the wing. Complete: 5 Sept 2025.

- Phase 4: Transition: The VX4 prototype will transition between thrustborne and wingborne flight, and vice versa. Underway and full transition expected before YE 2025.