air lane vs flight path

air lane and flight path both are nouns.

Word	Noun	Adjective	Verb	Adverb
air lane	Yes	No	No	No
flight path	Yes	No	No	No

As nouns, air lane and flight path are synonyms defined as:

air lane and flight path: a designated route followed by airplanes in flying from one airport to another

Other synonyms of air lane include airway, skyway.

air lane (noun)	flight path (noun)
a designated route followed by airplanes in flying from one airport to another	a designated route followed by airplanes in flying from one airport to another
	the path of a rocket or projectile or aircraft through the air