Originally Posted by
Pringle_
One of the drawback is that crews don't always enter the correct callsign. <-- the same could be said for entering the correct SSR code, both are easily changeable as far as I'm aware.
My understanding is that ORCAM codes are still issued because not every ATCU uses mode-s as the primary means of identification. It also helps if an aircraft is squawking a discrete unit code a service is being provided outside of controlled airspace as the controller knows which unit to get traffic information/coordination from.
This is correct. Just because aircraft are fitted with these snazzy modern bits of kit it doesn't mean every radar unit with a jobsworth watching the purse strings has the facility to display the information.