The 29-year-old ground service agent, whose name was not released, hijacked a 76-seat Q400 aircraft belonging to Alaska Airlines' regional carrier Horizon around 7:30 p.m.
He said the pilot then "pulled pretty much straight up and kind of at an angle", adding he "somehow he got it levelled back off and then made his way down toward the island".
The plane crashed either while the man was doing stunts or because of a lack of flying skills, according to the Sheriff's Department.
Witnesses reported seeing the plane being chased by military aircraft before it crashed.
Still, the episode appears to expose alarming gaps in airport security in the post-9/11 era, according to experts.
The incident shut down Sea-Tac Airport but flights are returning to normal.
Later, Mr Russell said: "I've got a lot of people that care about me". I would like to apologize to each and every one of them. Just a broken guy, got a few screws loose I guess. "Never knew it, until now".
People on Twitter who were following the aviation audio reported that the man attempted a "barrel roll" with the plane at one point - or at least claimed he was going to do so. "We will provide more details when appropriate". I don't know! I don't want to.
A Horizon Air Bombardier Dash 8 Q400, reported to be hijacked, flies over University Place, Washington, the US, before crashing in the South Puget Sound, August 10, 2018 in this still image taken from a video obtained from social media.
Earlier in the flight, the man says: "This is probably, like, jail time for life, huh?"
Investigators expect they will be able to recover both the cockpit voice recorder and the event data recorder from the plane. Two F-15 jets were scrambled in response to the stolen plane from the Oregon Air National Guard in Portland, Oregon.
"I don't know, man", the pilot answers. After flying around an unpredictable path, the plane crashed at a nearby island.
"The person who stole it was either doing it on a lark, or was suicidal", Pastor said, adding there was no indication anyone else was on the plane. While the jets were in pursuit of the small plane, air traffic control helped the rogue plane stay clear of the Seattle cosmopolitan area.
"If that goes good, I'm going to go nose down and call it a night", Rich says. Near the end of the video, you can also see the aftermath of the crash. "It's going to disappoint them to hear that I did this".
A sheriff's department spokesman said the man may have been suicidal but there was no terrorism connection.
"The FBI continues to work with our state, local, and federal partners to gather a complete picture of what transpired with tonight's unauthorized Horizon aircraft takeoff and crash", the agency said.
Press Secretary Sarah Huckabee Sanders said Saturday morning Trump is monitoring the situation.
The statement was read by family friend Mike Matthews, on behalf of Mr Russell's loved ones, who pleaded for privacy for the family and said this would be the only time the family would address the media.
Only minutes after the plane made its weird, unauthorized takeoff around 8 p.m., the North American Aerospace Defense Command (NORAD) scrambled two F-15s out of Portland to intercept it.