A 27-year-old man's ambitious plan to propose to his girlfriend after scaling a cliff face led to a rockier road than he might have imagined after he had to be winched to safety by a rescue helicopter.

Michael Banks climbed Morro Rock, just off California's Central Coast, to propose to his girlfriend, who was watching via FaceTime video.

The good news for Mr Banks was that his girlfriend said yes; the bad news was that he got stuck.

Morro Bay fire captain Todd Gailey said Mr Banks "took a different trail down, much steeper" and became stranded.

"He couldn't go any direction, on a sheer ledge, with his feet dangling 80ft off the ground."

A rescue helicopter was called in, with Capt Gailey descending by cable to hoist Mr Banks from the narrow ledge in a tricky operation, with the rotors spinning close to the cliff and ocean spray battering both men.

Mr Banks was calm for most of the ordeal, but "a little unnerved" during the crucial airlift, Capt Gailey said.

Morro Rock is a landmark located just offshore from the community of Morro Bay. Climbing is banned but some people attempt the ascent anyway, and there have been several fatal falls over the years.

Typically when someone needs to be rescued they are fined, Capt Gailey said. It was not immediately clear if Mr Banks, who was unharmed in the incident, was punished in any way.

Mr Banks said nothing during the rescue about any second thoughts on his choice of setting for the proposal, Capt Gailey said.

However, the fire captain suggested that other romantics should consider a place "where you're not in danger of falling off a cliff".