I can’t help but stir this pot…
As you may know, the old way of seperating aircraft was having one STAR for props, and one for Jets. The only place they got tangled up with on the vector to final, which approach controllers could handle with some slick speed and altitude adjustments.
Lately, props have been let go by most companies (piedmont and horizon the names that come to mind that still fly dashes) and have been replaced with slow jets. This has created some big problems in the enroute world. There used to be a 70/30 split of traffic, with similar speeds on similar routes. Now, there is a 90/10 split of traffic, and the 90 percent isn’t all as fast as the big boys would want.
On top of this, airlines are implementing “fuel conservation programs” to save money. Basically, if a flight is running a little early, they message the pilot via ACARS to slow way down to save gas. One that comes to mind, is an EGF E145 that requested M0.60 at FL350. That will NOT work for in trail spacing in most cases. So, the FAA is going to do thier best to think up a solution for where to put all these high flying slow as hell jets.
So far, the best they have come up with is NRP-Qroutes. Well, at least they plan on using that technology as that premise to solve the problem. Basically, the idea is that each major city pair would have two routes. One would be for fast jets, the other for slower jets. Both would be flexable to go around weather, and get the best fuel economy using the winds aloft. Then, each STAR would be changed to best suit the climb and descent characteristics of newer planes. Seperation will soon be based upon newer jets climbing at 4500 fpm in RNAV SIDs that include VNAV. LIkewise, STARs will assume jets descneding like thier FMC would like as well.
Again, this isn’t a final plan. ALot of it still in testing. However, from direct observation of the NAS, I have realized what the future holds, and it will be MUCH different that you expect. It won’t include everyone going direct as they please. Not free-flight-esq. Instead, the routes will be more like NAT tracks. Flexable and user friendly. The question is, how to do you create ATC sectors based on routes that aren’t always in the same place? Perhaps bigger sectors with URET and datalink?