There was similar speculation about a Sturgeon-class attack sub, SSN-687, possibly associated with the incident below.
On Friday, Horizon Air ground service agent Richard B. Russell got in one of the airline’s Bombardier Q400 aircraft and took off from Seattle’s SeaTac Airport. In audio recordings released over the internet, Russell can be heard chatting in an upbeat, enthusiastic tone with the air traffic controllers trying to talk him down.
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the Q400, which ultimately crashed into Ketron Island, about 30 miles from the airport.
https://www.popularmechanics.com/flight/airlines/a22713369/richard-russell-ground-crew-steal-planes/