As the crow flies and First off

As the crow flies adverb - By the shortest and most direct route.

First off and as the crow flies are semantically related. In some cases you can use "First off" instead an adverb phrase "As the crow flies".

First off adverb - Before anything else.

As the crow flies and first off are semantically related. You can use "As the crow flies" instead an adverb phrase "First off".