I'm interested in what FEDex are doing re self spacing for landing (by airborne systems)?
Do you mean FedEx in Memphis (MEM) or UPS in Louisville (SDF) ?
My info is a couple of years old but...
FedEx was getting cute -- their dispatchers (reportedly) were telling them to slow down or speed up (hundreds of miles out) trying to set up their arrival times -- forgetting to tell ATC. Supposedly (again, just rumor) a few would ask for a reroute to a different arrival becuase the dispatchers were shuffling gates.
UPS has a full-blown experimental program using ADS-B and Continous Descent Approaches (CDAs). All the eggheads and managers think CDAs are the best thing since beer. I don't know of any controllers that think they will work in congested airspace. I
know they didn't work well at ATL or CLT. (Very limited experiments on the midnight shift.)
Experiments on the midnight shift at an isolated airport (SDF) with just one company (UPS) isn't going to tell us much about the real world.
Don Brown