VIRGIN Galactic aborted a “milestone” test flight yesterday just minutes after getting the all clear.

Dave Mackay, from the Scottish Highlands and the first Scot to go into space, was one of two pilots on board Virgin Galactic’s VSS Unity, which was due to take off at 8am MT – around 3pm GMT.

While the space plane was successfully launched to an altitude of 9.4 miles (15km) it failed to de-couple from its mothership.

In a tweet, the company said: “The ignition sequence for the rocket motor did not complete.

“Vehicle and crew are in great shape. We have several motors ready at Spaceport America.

“We will check the vehicle and be back to flight soon.”

The cancellation follows the tragedy in 2014 when the company attempted its first test launch. SpaceShipTwo broke apart during flight and crashed, killing one pilot and seriously injuring another after parachuting.

Sir Richard Branson’s company is expected to begin space tourism flights in 2021, with Justin Bieber and Leonardo DiCaprio among the first 600 paying customers who have signed up so far.

Yesterday’s flight was supposed to be the first of three final demonstration flights before the tourism service begins next year.

Former Nasa astronaut CJ Sturckow joined chief test pilot Mackay on the flight. They were both wearing special suits which were specifically designed to support flying regularly at more than three times the speed of sound into space and back.

Before the launch, Mackay said: “It’s a real honour for all of us in the Virgin Galactic Pilot Corps to wear these spacesuits.

“The thoughtfulness of the design ensures the suits are not only comfortable and practical, but also bespoke to each pilot.

“As soon as you step into the suit, you immediately get a sense of the significance of our mission.

“I’m very much looking forward to wearing my own spacesuit during New Mexico’s first human spaceflight and then many times in the future as we share the wonder of space with our Future Astronauts.”

The flight was expected to fulfill several objectives, including testing elements of the customer cabin as well as assessing the upgraded horizontal stabilisers and flight controls during boost. The flight also carried payloads as part of the Nasa Flight Opportunities Program.