Flight ID
Mode - S for flight id is not restricted by the age of the processors but the current lack of complete cover, mode 3A ground based systems (airport movement) and the need to communicate with other non-mode-S neigbouring ATSUs.
It is a great shame given the money that we will have to spend on a central european Mode 3 A assigner (CCAMS).
Our new FDP system replecement is also not Mode-S compatible (yet).
To have to change Mode 3A codes at busy times (due to a lack of investment not just by NATS) is a poor situation.