Questions are swirling since a Horizon employee stole a plane from Sea-Tac Airport Friday. 28-year-old Richard Russell took the plane from a storage hangar and pulled it to a nearby tarmac.

According to Alaska Airlines and federal investigators, the ground service agent was able to tow the Q400 out of a cargo area on the northern edge of the airport and redirect it using a tractor.

This is normal activity in the cargo area, according to former NTSB investigator Greg Feith. Russell "probably wouldn’t have drawn suspicion by anybody, given the qualifications,” Feith said Sunday.

RELATED: Childhood friend doesn't believe Russell was suicidal when he stole the plane

Russell had passed background checks and had all the credentials to be in the area. It was only after he taxied a couple hundred feet to runway 16C when air traffic controllers became suspicious.

“Who’s the aircraft on 16 Center?” said one controller on audio obtained by KING 5. Another noted: “His wheels are smoking left and right, uh, as they are right now, rolling down the runway.”

“He came flying out of the cargo area,” reported the controller. “We need to call and scramble now.”

WATCH: Questions remain in the wake of the Horizon Airlines stolen plane incident

“It would only have been a matter of minutes,” noted Feith, who also said it would be tougher to try and stop the plane than some people may think. “To try and send a fire truck out there, or an operations vehicle, to get on the runway and block a takeoff, or taxiway, you create an undue hazard to the people in that vehicle. You have spinning propellers, you create a collision,” he said. “You create a safety hazard.”

Russell flew the plane, at times erratically, for more than an hour before crashing into a small Pierce County Island. On Sunday, the FBI located Russell's body and the plane's flight data recorder from the wreckage on Ketron Island.

Aviation security expert Jeff Price said Sea-Tac Airport did what they were supposed to in terms of keeping unauthorized from accessing the airfield, because Russell was credentialed.

LISTEN | Horizon employee talks with air traffic control in cockpit

"It’s actually a specific airline responsibility, there’s a transition of responsibility there, to prevent unauthorized people on the airplane itself," Price said. "I think from an airline perspective what they’ll have to do is revise their procedures about who is allowed on the aircraft, when the aircraft is being serviced or when the aircraft is not being attended."

Price said incidents like this are preventable if someone noticed early that something was not right.

"That is going to make everybody aware that there are layers of security that you don’t see," Price said. "Most people see the checkpoint and think that’s it. There’s other layers out there and I think there’s going to be a renewed focus in those types of areas."

WATCH: Debris cleared on Ketron Island after plane crash

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