Virgin Galatic's six-passenger SpaceShipTwo successfully fired its rocket engines in flight for the first time on Monday, marking a big milestone for the company, and for the private spaceflight industry as a whole.

The SpaceShipTwo's engines burned for 16 second to a speed of about 1.2 times the speed of sound and an altitude of 17 000 meters, according to the Wall Street Journal. This marks a critical step toward the goal of launching commercial operations in 2014.

The project has incurred its fair share of delays for its operations based out of Spaceport America in New Mexico-the original timetable of 2008 slipped to 2010 and then 2012.

Watch a video of the SpaceShipTwo below:

"It was stunning," Richard Branson, founder and chairman of the Virgin Group, told Reuters.

"You could see it very, very clearly. Putting the rocket and the spaceship together and seeing it perform safely, it was a critical day."

Branson said that everything went 100-percent according to plan, with SpaceShipTwo's hybrid rocket motor blasting away on a 16-second burn on its first-ever in-flight test. "The pilots said it was as smooth as anything," he said.

A ticket on Virgin Galactic's SpaceShipTwo is not cheap at $200,000 per person. More than 500 people have put down deposits. Branson said the price will remain that high until after 1,000 passengers have travelled. 

SpaceShipTwo is based on a three-person prototype called SpaceShipOne, which in October 2004 clinched the $10m Ansari X Prize for the first privately funded human spaceflights.