[rdpintqogeogsaa]

From what I can tell, at least it's historically inherited. 4.4BSD had a list of airports in the same location.

Its inclusion in 4.4BSD seems a mystery though. No other files on the 4.4BSD distribution seem to reference it. The atc(6) game involves airports, but it doesn't seem to actually open this file, both in 4.4BSD and in OpenBSD.

[fanf2]

It goes back a bit further than that, to 4.3BSD-Reno https://minnie.tuhs.org/cgi-bin/utree.pl?file=4.3BSD-Reno/sh...

The previous release, 4.3BSD-Tahoe, did not have /usr/share