HAV said it had applied for Type Certification, which signifies the airworthiness of a particular category of aircraft, and a process with the Civil Aviation Authority for its Airlander 10 was underway, as it seeks to commercialise a new type of flying.

The Airlander 10 emits up to 90% less carbon than conventional flying although it is much slower, with journeys expected to take just under double the time.

But its sustainable credentials mean HAV has already secured interest from airline customers like Spain's Air Nostrum, and HAV believes its Airlander could be in service by 2028.

"Applying for Type Certification is a key milestone in our journey," said HAV Chief Executive Tom Grundy.

In 2016 Airlander, nicknamed the "flying bum" after its double-hulled shape, crash landed during trials, and a year later it was pictured ripped and deflated after it came loose from moorings.

But HAV said it has improved its technology since then.

Using aerodynamics, buoyancy and vectored thrust from four combustion engines, the Airlander flies at about the same altitude as a helicopter when it is pumped full of helium, a key difference from the hydrogen-filled airships made infamous by the Hindenburg disaster of 1937.

Airlander's hardened fabric shell is almost as long as a football pitch and the height of six double decker buses, and it carries a cabin below which can fit 100 seats.

HAV said it will agree a plan with the CAA to set out the basis for certification which will include analysis, simulation, laboratory, ground and flight tests.

(Reporting by Sarah Young; Editing by Chizu Nomiyama)