The theft of an empty plane by an airline worker who performed dangerous loops before crashing into a remote island in Puget Sound in Washington state has illustrated the potential perils of airline or airport employees causing mayhem.

Video footage shows a 76-seater Horizon Air Q400 aircraft which was stolen from Sea-Tac International Airport carrying out large loops and other dangerous manoeuvres as the sun set on Puget Sound near Seattle.

The flight lasted about 75 minutes, and ended when the pilot, named by sources as Richard Russell, crashed into the small island after being chased by military jets. The two F-15C aircraft scrambled from Portland did not fire on the plane, authorities said.

Erroll Southers, a former FBI agent and transportation security expert, said: “The greatest threat we have to aviation is the insider threat.

“Here we have an employee who was vetted to the level to have access to the aircraft and had a skill set proficient enough to take off with that plane.”

Mr Southers said the man could have caused mass destruction.

He said: “If he had the skill set to do loops with a plane like this, he certainly had the capacity to fly it into a building and kill people on the ground.”

Richard Russell's friendsFriends of Richard Russell talk to the media (AP)

Officials said the man had worked with Horizon for three-and-a-half years, and had clearance to be among aircraft. To their knowledge, he was not a licensed pilot, and he took the empty turboprop plane from a maintenance area.

It is unclear how Mr Russell attained the skills to carry out loops in the aircraft. Ground service agents direct aircraft for take-off and gate approach and de-ice planes, as well as handle baggage.

Horizon Air CEO Gary Beck said it was not clear how the man knew how to start the engine, which requires a series of switches and levers.

At a news conference, officials from Alaska Airlines and Horizon Air said they are working with authorities.

The crash siteThe site of the crash on Ketron Island (AP)

Brad Tilden, the CEO of Alaska Airlines, said: “Last night’s event is going to push us to learn what we can from this tragedy so that we can ensure this does not happen again at Alaska Air Group or at any other airline.”

Investigators expect they will be able to recover both the cockpit voice recorder and the event data recorder from the plane.

Mr Russell could be heard on audio recordings talking to air traffic controllers, who tried to convince him to land the plane.

“There is a runway just off to your right side in about a mile,” the controller said, referring to an airfield at Joint Base Lewis-McChord.

The site of the crashThe turboprop plane was stolen from Sea-Tac International Airport (AP)

“Oh man. Those guys will rough me up if I try and land there,” Mr Russell responded, later adding: “This is probably jail time for life, huh?”

Later, Mr Russell said: “I’ve got a lot of people that care about me. It’s going to disappoint them to hear that I did this … Just a broken guy, got a few screws loose, I guess.”

Mr Russell’s family said in a statement that they were stunned and heartbroken.

They referenced the recordings and said it is clear Mr Russell, who went by the nickname Beebo, did not intend to harm anyone and “he was right in saying that there are so many people who loved him”.