Okay, I understand about ATC and callsign confliction and the need for alpha numeric call-signs.
The second part of the question being the naming covention used. Someone makes a conscious decision that RYR99TR inward is becomes RYR35LK outward. Why not RYR99TS or RYR100TR? There must be a system for naming call-signs RYR and others use.
Somone must know the answer!
airsmiles.