The man, an airline employee, stole the 76-seat Horizon Air plane from Seattle-Tacoma International Airport on Friday.
Kaelin said it has been painful for him to hear reports with audio of Russell's conversations with air traffic control during the flight that ended with him crashing on Ketron Island, about 25 miles southwest of where he took off.
The official wasn't authorised to discuss the matter and spoke on the condition of anonymity.
The 29-year-old used a pushback tractor to first manoeuvre the aircraft so he could board and then take off on Friday evening, authorities added.
Officials at the Sea-Tac Airport say an airline employee conducted an unauthorized takeoff in Washington state and has crashed.
"Our hearts are with the families of the individual aboard as well as all of our Alaska Air and Horizon Air employees", said Constance von Muehlen, the airline's chief operating officer.
"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", he said. The plane crashed either while the man was doing stunts or because of a lack of flying skills, according to the Sheriff's Department.More news: Gerard Pique: Barcelona and Spain confirms global retirement
The FBI Seattle field office on Friday said early signs do not point toward terrorism.
Video taken by a bystander showed the passenger airplane making an unlikely upside-down loop, then flying low over Puget Sound before crashing into the sparsely populated Ketron Island in the northwestern U.S. state of Washington. There were no passengers aboard.
A ground service agent's responsibilities don't involve touching planes' controls, CNN aviation analyst Mary Schiavo said.
Southers said the man could have caused mass destruction.
Video showed fiery flames amid trees on the island, which is sparsely populated and only accessible by ferry.
In a video posted on YouTube last December, Russell shows luggage coming off and being loaded onto aircraft, and describes what the life of a ground service agent can entail.
Alaska Airlines and Horizon Air officials said they were still working closely with authorities to investigate what happened.More news: British pound falls lower against dollar, euro
Flights were grounded with some passengers tweeting that their plane stopped abruptly on the runway. Horizon Air is a division of Alaskan that flies shorter routes in the western US.
Two F-15s fighter jets pursued the plane but were not involved in the crash, local TV station KIRO7 reported. Although he never claimed he was trying to kill himself while conversing with air traffic controllers, some of his comments about never intending to land the plane and having a few "screws loose" indicate he may have had suicidal intentions and/or was mentally ill.
After a ride full of unsafe loop-the-loops moves and weird conversation with the air traffic controllers, Richard wasn't able to land safely and crashed into a heavily wooded area on Ketron Island causing the jet became engulfed in flames.
The man sounds calm at times and jokes with operators on the ground, who try to direct him to places to land.
Horizon president and CEO Gary Beck said that to the airline's knowledge the man who took the plane did not have a pilot's license. "I would like to apologise to each and every one of them", he said. "Normal operations at Sea-Tac Airport have resumed", the airport wrote.
Eckrote said it was very fortunate that the plane crashed in a relatively unpopulated island.More news: New Zealand to ban single-use plastic bags
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