Veritcal Aerospace begins pivotal phase 4 testing following Civil Aviation Authority clearance

Vertical Aerospace has secured approval from the Civil Aviation Authority (CAA) enabling the start of “Phase 4 – Transition” in its flight‑test programme for the four‑passenger VX4 eVTOL aircraft. Successfully completing phase 4 is crucial for certification and Vertical Aerospace’s plans to launch commercial operations in 2028.

image: Vertical Aerospace

The permit authorises piloted transition flights – the key capability to shift from vertical (hover) to wingborne (airplane‑mode) flight. Essentially this is the point where an eVTOL proves it can do what makes it unique – combining vertical take-off and landing with efficient forward flight – and sets the stage for certification and commercial use.

To prepare for this latest phase in development, 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 the 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 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. Phase 4 is a critical demonstration of the VX4’s unique tiltrotor capability and a major technical and certification unlock.”

Vertical Aerospace progress towards phase 4:

• Phase 1: Tethered: the VX4 prototype will perform stabilised hover while loosely tethered to the ground. Completed 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. Completed February 2025.

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

• Phase 4: Transition: The VX4 prototype will transition between thrustborne and wingborne flight, and vice versa. Underway and full transition expected by the end of the year.