Vertical Aerospace has received its Permit to Fly from the UK Civil Aviation Authority, entering Phase 4 transition flight testing for its VX4 prototype. The approval has enabled the company’s flight test team to begin evaluating the defining transition manoeuvre between hover and wingborne flight referred to as helicopter mode and airplane mode.

Phase 4 represents the final stage of the VX4 prototype flight test programme and follows the completion of Phases 1 to 3 earlier in the year. Those phases confirmed the aircraft’s flying qualities and included operating in open airspace for the first time. To prepare for piloted transition engineering and test teams recently completed extensive simulation ground testing and flight testing with the UK CAA while verifying all 200 Minimum Safe Aircraft requirements. Test pilot Paul Stone flew the first flight of this phase at on the morning of 13 November.

More than 20,000 pages of updated safety and technical information were submitted to the CAA in support of the Permit to Fly. The authority is working with EASA on certification and concurrent validation of the VX4 to commercial safety standards.

Stuart Simpson, CEO, Vertical Aerospace, says: “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.”