N378QS is taken. It's currently assigned to a 2006 Cessna 680.
See the full aircraft record →Checked against FAA data from Jul 27, 2026. Not an official FAA determination — always confirm with the FAA before filing.
A tail number only frees up if the owner deregisters the aircraft or moves it to a different N-number — and even then the FAA holds it before releasing it to the public.
N378QS has been worn before. Past registrations from FAA deregistration records:
Tails one nudge away from N378QS that aren't assigned or reserved: