AA Callsigns

[CesnaCaptn]

Why does American Airlines use alphanumeric call-signs? Today I heard one ending in papa.

 

[snowback]

It's most likely to avoid having the same two callsigns in the air at the same time.

Say there's a flight #123 from Nashville to Las Vegas with a stop in Dallas. If the BNA-DFW leg is 3 hours late, but the company wants to get the DFW-LAS flight out on time, they may add a letter to the callsign to avoid having the same callsign arriving and departing at the same time. Delta uses 9000 series flight numbers when that happens.

 

[CesnaCaptn]

I figured that, but the papa part seems arbitrary.