ADS-B and Mode A/C/S (MSSR) are both secondary radar. but the equipment differs, in particular the ground equipment looks different. It could be that the MSSR e

ADS-B and Mode A/C/S (MSSR) are both secondary radar. but the equipment differs, in particular the ground equipment looks different. It could be that the MSSR equipment gets phased out as ADS-B prevails. Primary radar will continue to be used though, in particular at airports (ones other than the many local uncontrolled variety).