> I can't imagine what would've happened if we adopted block signaling for ATC ...
You don't have to imagine. We already do in many places. The North Atlantic Tracks are essentially exactly that. Aircraft give position reports and estimates, those positions reports are used to decide whether an aircraft can climb though which levels etc.
It's also used extensively in an IFR non-radar environments. Exactly why aircraft have to cancel IFR at uncontrolled airfields in the US or under a procedural ATC service in the UK. You hear it a lot around the Caribbean and Bahamas too.
You don't have to imagine. We already do in many places. The North Atlantic Tracks are essentially exactly that. Aircraft give position reports and estimates, those positions reports are used to decide whether an aircraft can climb though which levels etc.
It's also used extensively in an IFR non-radar environments. Exactly why aircraft have to cancel IFR at uncontrolled airfields in the US or under a procedural ATC service in the UK. You hear it a lot around the Caribbean and Bahamas too.