[4] Over the following years, Harbor Airlines encountered a series of financial problems, which culminated in being evicted from Seattle–Tacoma International Airport (the most important destination in its route network) in March 2001 due to unpaid bills worth US$100,000.

[3] In the mid 1970s, destinations included Seattle, Oak Harbor, Bellingham, and Hoquiam in Washington State; and Astoria and Portland in Oregon.

[2] Hoquiam began as a destination in July 1974 when Harbor took over a route from Hughes Airwest, but was discontinued in January 1975 due to lack of business.

Flight 308, a Britten-Norman Islander (registered N66HA) en route from Seattle to Oak Harbor crashed in Riverton, Washington four minutes after takeoff, killing four of the six occupants (the pilot and three passengers) on board.

During the subsequent investigation, an unknown substance was found inside the pitot tubes of the aircraft, which had caused unreliable airspeed readings.