The Coast Guard is searching the waters off the coast off of Nauset beach in Orleans after a plane that was set to land in Chatham never arrived.
The plane, a small single-engine Piper 28, had been due to land in Chatham Sunday night.
Teams began the search overnight after it was notified something went wrong at around 10:30-pm.
The Harwich, Chatham and Orleans harbormasters are also assisting in the search.