I believe (Could be wrong) That certain chief are "Air Recon Trained" if that's even a thing.
ARC was established before Drone Units
Its usually Brooklyn BCs since they have to go to Floyd Bennet Field.
Dating back (Forgot the date)
9X6 Chief working that were AR trained were B3,38,39,41,42,58
And for the 6X9 were 21,33,39,40,42,58
But the 58 was the 1st up ARC when needed. If the 58 should be unavailable. Not sure which would be next up