Vertical Aerospace, a pioneer in electric aviation, has achieved a pivotal milestone by receiving its Permit to Fly from the UK Civil Aviation Authority (CAA). This approval initiates ‘Phase 4 – Transition’ flight testing, the final stage for its VX4 prototype. This critical phase focuses on testing the aircraft’s defining manoeuvre: seamlessly transitioning between hover, or “helicopter mode,” and efficient wingborne, “airplane mode” flight.
The first flight of this phase was successfully piloted by Paul Stone on 13 November 2025. This transition capability is the core technological unlock for the VX4, a tiltrotor aircraft designed for urban air mobility. ‘Phase 4’ builds upon the completion of earlier flight test phases, which validated the prototype’s exceptional flying qualities and operation in open airspace.
Preparation for this milestone was extensive. Vertical’s engineering and test teams collaborated closely with the UK CAA, completing rigorous simulation, ground testing, and flight testing to verify over 200 Minimum Safe Aircraft requirements. This robust approach to certification was supported by the submission of more than 20,000 pages of safety and technical information to the regulator.
The UK CAA is working in tandem with the European Union Aviation Safety Agency (EASA) for the concurrent validation and certification of the VX4, ensuring it meets the highest safety standards required for future commercial operations.
CEO Stuart Simpson hailed this as a defining moment for the company, underscoring it as a major technical and certification achievement that demonstrates the VX4’s real-world capability. This progress follows a recent business update where Vertical also shared a first look at its new certification aircraft’s leading cabin design, highlighting its focus on passenger comfort for the advanced air mobility market.
