UPS is a bit unique in that they are pretty much monopolizing airports where they have hubs at their busiest times - There's not many pax flights going into Louisville in the middle of the night. But, UPS' own planes all descend upon KSDF in a pretty short timeframe, which was resulting in lots of low altitude holding and vectoring, which was using a LOT of fuel.
The solution they built uses ADS-B and a method of communicating back to the planes (I don't know the specifics of that part). They can use the data they receive on the ground to very accurately determine the time when each flight is going to arrive in the SDF area, and then they send a signal back to the planes and slow down some of the flights by a few knots, such that the aircraft hit the arrival gates into SDF at even intervals and get sent right down the approach, eliminating the low-level delays and associated fuel.
It was proposed that eventually, when everyone was equipped, that it would be possible for airlines to cooperate with each other to achieve the same thing going into busy hub airports, but that doesn't appear to have happened yet.
You already do that, trusting that Bob's Bonanza has an encoding altimeter that's working properly... Obviously that's only one of the three dimensions but it is an important one. Plus, it should be easy enough using only long-range Center radars to determine whether Bob's ADS-B is working properly. It was never intended to replace ALL radar.
Interesting, guess they wanted a more real time always on company position report, which we normally send via ACARS at predetermined time intervals or if asked
Per radar, not exactly, you still have a live primary target, and the reason you need two way radio radio comms is also altitude verification, hence when someone isn’t talking to ATC, they will give you the location and altitude of traffic but add “altitude unverified”
Maybe someone marketed replacing all radar with ADSB, but I promise you that day was never going to come, for many reasons
Someone has a electrical issue, no comms no ADSB, gets lost and flys through the approach corridor, in the all ADSB no radar world he would be invisible until someone hopefully saw him out the window, or smashed into him
The fidelity issue, ADSB is just not fast enough nor accurate enough for tight work, let alone if some poor soul needs to be walked down
National security, no radar no detection of aircraft without ADSB out, I’m sure you can see where that goes
GPS, if there was a solar flair or other wide GPS issue, you would have to stop all IFR flights, airlines, medevacs, cargo, charter, everything
