Green’s Dictionary of Slang

air loft n.

(US Und.) a warning to run away.

[US]‘Boxcar Bertha’ Sister of the Road (1975) 173: When [the police] were coming he gave us the ‘Air-loft,’ or warning to get away.

In phrases

take the air loft (v.)

to make an escape after being given a warning of problems, e.g. a police raid.

[US]‘Boxcar Bertha’ Sister of the Road (1975) 184: Many times we had to take the air loft, but there was no actual raid until the last Saturday I was there.