U.S. aviation authorities won’t permit Virgin Galactic Holdings Inc. to fly its space plane until an investigation is complete into whether a July 11 flight deviation threatened public safety.

The Federal Aviation Administration is reviewing why SpaceShipTwo flew outside the area in which it was cleared by the agency during the trip to space that carried company founder Richard Branson and others. The flight landed safely.

“Virgin Galactic may not return the SpaceShipTwo vehicle to flight until the FAA approves the final mishap investigation report or determines the issues related to the mishap do not affect public safety,” the FAA said in an emailed statement.

The company is working with FAA to address the flight deviation, which didn’t endanger the passengers or the public, it said in an emailed statement. 

“We take this seriously and are currently addressing the causes of the issue and determining how to prevent this from occurring on future missions,” it said in the statement. “We have been working closely with the FAA to support a thorough review and timely resolution of this issue.”

The FAA news sent Virgin Galactic shares down 2.9 per cent to US$26.01 at the close in New York.

Virgin Galactic was planning its next flight to the fringes of space for later this month or in early October. The research flight is scheduled to include two members of the Italian Air Force, an aerospace engineer and a Virgin Galactic employee, the company said Thursday in an earlier statement. Virgin declined to comment on whether the FAA’s edict would alter that flight’s schedule.

It will be the company’s first commercial research mission. 

The FAA regulates commercial space flights and sets rules to protect the uninvolved public on the ground and other aircraft near launches. But Congress has prohibited it from setting safety standards for crew members. 

The flight deviation occurred because the spacecraft, which floats back into the atmosphere using devices designed to keep it stable and limit its speed, was outside the optimal descent path, the New Yorker reported Wednesday.

The ship, which becomes a glider once it reenters thicker air, flew beneath an area that FAA had set aside to prevent conflicts with other aircraft, the company said on Wednesday. It was outside the protected area for one minute and 41 seconds, it said. 

It then reentered protected airspace for the remainder of the flight, according to the company. 

“Although the flight’s ultimate trajectory deviated from our initial plan, it was a controlled and intentional flight path that allowed Unity 22 to successfully reach space and land safely at our Spaceport in New Mexico,” the company said in a statement Wednesday.