flying bridge vs fly bridge

flying bridge and fly bridge both are nouns.

Word	Noun	Adjective	Verb	Adverb
flying bridge	Yes	No	No	No
fly bridge	Yes	No	No	No

As nouns, flying bridge and fly bridge are synonyms defined as:

flying bridge and fly bridge: the highest navigational bridge on a ship; a small (often open) deck above the pilot house

Other synonyms of flying bridge include flybridge, monkey bridge.

flying bridge (noun)	fly bridge (noun)
the highest navigational bridge on a ship; a small (often open) deck above the pilot house	the highest navigational bridge on a ship; a small (often open) deck above the pilot house