Caitlin O'Shannessy enters the series the way she lives it: mid-flight, mid-argument, and completely unwilling to back down. When Hawke first crosses her path in Season 2's 'Sweet Britches', she is a Texas Highway Patrol helicopter pilot in Pope County — dismissed by a crooked sheriff as a glorified traffic cop, and about to prove exactly how wrong that assessment is.
The corruption case that brings Hawke to Texas costs Caitlin her illusions and nearly her life — and when the dust settles, she follows the mystery of the man and his impossible black helicopter all the way to California. Dom hires her at Santini Air for her flying; the audience keeps her for everything else. Feisty, red-headed and immune to Hawke's brooding, she becomes the third seat the team never knew it was missing (she tells the story of how she talked her way in during 'The Truth About Holly').
Across Seasons 2 and 3, Caitlin logs hours no highway patrol ever imagined: surviving a hijacked airliner's ditching in 'Flight #093 Is Missing', wearing a bomb in 'Kingdom Come', and holding her own in the Airwolf cockpit whenever the mission needs a third pair of hands. She lightens a famously dark show without ever becoming its comic relief — her courage is played absolutely straight.
When the series was rebuilt for its fourth season, Caitlin was simply never mentioned again — one of fandom's longest-running sore points. Jean Bruce Scott's two seasons remain, for many fans, the classic line-up's defining era.