Do you ccept the FMC descent prediction or over-ride it?

[davidz]

Outside of the United States it's common because most places don't have the traffic volume or the fleet mix to go against magenta lining it from departure to destination.

 

I wouldn't agree that it's due to traffic volume and fleet mix that major US airports don't utilize RNAV STARs to the IAF.

 

Look at the technology that controllers are having to use to manage the traffic - in other places, aircraft are sequenced well prior to arrival (Australia and Europe are examples where aircraft are often sequenced before they leave the ground) and delaying action is taken well before the TMA. This allows aircraft to enter the TMA with sufficient spacing for Approach controllers to make final adjustments to the spacing with speed control and minor track adjustments.

 

Traffic mix is not necessarily a barrier to using RNAV STARs to the IAF. The best solution is probably segregation of routes and possibly even segregation of runway usage (if possible - perhaps this is even more feasible in the US where there is a higher percentage of non-jet public transport aircraft as well as more runways available at many ports). Non-similar types can be merged at a late stage (e.g. IAF or a little bit before) with the merge planned well in advance with the automated sequencing tools, supplemented by speed control and minor track adjustments by the Approach controllers.

 

Possibly the other complexity that the US faces in many TMAs is the number of significant aerodromes in the one TMA (NY and SOCAL are probably the most obvious examples). However, the STARs can be designed to route aircraft via existing vectored paths and also build in vertical separation at crossing points.

[Overload]

the FPV is your friend

Never really understood how to use the FPV to my advantage. I kinda understand what it's telling me, the projected path of the aircraft both vertically and horizontally, if my understanding is right, but never seemed to see the practical advantage when flying. I've always felt I might be missing a trick, am I?

Eugene

PS Same goes for the rising runway - never taken much notice of it....either concentrating on the ILS or looking out the window, not sure how it fits in.

[scandinavian13]

 

 

I kinda understand what it's telling me, the projected path of the aircraft both vertically and horizontally, if my understanding is right, but never seemed to see the practical advantage when flying. I've always felt I might be missing a trick, am I?

 

Glide path is 3 degrees, so you can put the FPV on the 3 degree line of the PFD and bang - right on the money.  No need to try and figure out a good VS for approach.

 

Also, it'll show you your drift angle.  Compensating for the wind is pretty simple once you see how much deflection you're getting on the FPV.

 

 

 

Look at the technology that controllers are having to use to manage the traffic - in other places, aircraft are sequenced well prior to arrival (Australia and Europe are examples where aircraft are often sequenced before they leave the ground) and delaying action is taken well before the TMA. This allows aircraft to enter the TMA with sufficient spacing for Approach controllers to make final adjustments to the spacing with speed control and minor track adjustments.

 

We have a lot of traffic management software that does very similar, but only when absolutely necessary (and for some of the reasons you later mention).  So, we do the same thing, but only when we really need to.  There are a lot more efficient ways to sequence traffic without metering off of the gate or runway.  With that kind of metering everything has to work perfectly, or the ripple effect (given the traffic loads we see over here on the East Coast) can really mess up the system and be wholly counterproductive.

 

 

 

Traffic mix is not necessarily a barrier to using RNAV STARs to the IAF. The best solution is probably segregation of routes and possibly even segregation of runway usage (if possible - perhaps this is even more feasible in the US where there is a higher percentage of non-jet public transport aircraft as well as more runways available at many ports). Non-similar types can be merged at a late stage (e.g. IAF or a little bit before) with the merge planned well in advance with the automated sequencing tools, supplemented by speed control and minor track adjustments by the Approach controllers.

 

It really is, though.  If you don't have the advantage of multiple runways, then you can't utilize this.  Granted, here in the States, we generally have airports with multiple parallels, but this is not always the case.  Even with segregation of routes, you still need a merge point, and that must be sequenced to greater than the leading aircraft's required minimum separation.  We do have a couple offset STARs here to suit similar purposes, but since we're talking about STARs that dump onto the approach, you at least need to merge prior to the IAF.  This means that the main stream has to absorb the delay so that the outlier can operate at normal speed, or even with some slight delay.  Multiply this by each aircraft that does not fit the fleet mix and you have a ripple effect back for each normal operator.

 

You'll note that our high traffic, high fleet mix airports have absolutely no STARs that dump onto approaches for this very reason:

Our controllers take the traffic at standard separation and utilize vectors in order to allow the various flights to operate at closer to their optimal speeds.  This tactical approach allows controllers to apply a solution based on the current traffic picture.  The strategic approach, while smart and more optimal on paper, can only go so far unless you have the variances to allow it.  If the traffic levels allow enough spacing between the aircraft, without causing ripple delays back through the inbounds, then that's just fine.

 

As it stands, though, LGA has four distinct arrival streams to one runway.  Setting a restriction such that all streams combine down to minimum separation (with four streams, that 12nm per stream) would cause so much delay for that airport that it would make it almost not worth it to fly there for some operators.  This also assumes that each one of those aircraft would hit the appropriate fix with the exact stagger to be 3nm from the next at the merge point.  This is very difficult, especially in the case where you have props mixed with jets.  In order to cut some of that spacing and variance down, however, lower separation is used, and controllers tactically adjust the spacing through utilizing vectors extensively.  While this increases controller workload (and to some degree, the crew as well), it also allows the system to operate with higher overall efficiency.

 

 

 

Possibly the other complexity that the US faces in many TMAs is the number of significant aerodromes in the one TMA (NY and SOCAL are probably the most obvious examples). However, the STARs can be designed to route aircraft via existing vectored paths and also build in vertical separation at crossing points.

 

This is a smart thought, but the issue in the terminal areas isn't so much that of separation from other arrival streams.  Our STARs are developed to accomplish that, while still allowing variance at the end for tactical adjustment.  To illustrate that fact, you need only look at N90 (the NY area).  Aircraft are kept on separated arrival streams through the use of STARs.  The narrower margins in the airspace delegation actually restrict the amount of vectoring that can be done, but even then it's still used, which is rather telling.

 

The practice of magenta lining it from departure to destination simply won't work for the traffic mix and volume we see at some of our airports.

 

On the flip side, ATL and LAX do this where possible, but they also have four parallels to work with.  ATL also still uses vectors on the opposite-side arrivals, as well, to tactically sequence them into the gaps of the same-side arrivals.

 

 

 

I'm not saying it's wrong over there.  I'm just saying it doesn't quite work over here at some of our fields.  As we tend to avoid metering as much as possible (to avoid unnecessary delays to our operators, and maintain as much efficiency as possible), which also generally means we utilize a lot of tactical adjustment, which renders magenta lining it rather useless.

[davidz]

That's a fair analysis, Kyle, but keep in mind that even when you're using STARs that join the IAF, you are still free to take aircraft off the STAR - it's still not a walk in the park for the Approach guys. To be fair, you won't see this a lot in somewhere like Australia, but definitely in places like Europe and the Middle East, the Approach controllers are still doing significant work to fine tune the spacing down the minimum.

 

To this effort, you see two paradigms for STAR design that the Europeans/Middle Easterns are playing with. First is the Point Merge System that Oslo and Dublin are now using; second is the trombone pattern you see at many German ports and in Dubai. There is still a need to meter traffic because there is no point stuffing the TMA full of aircraft - this just raises the workload for no reason because now you are getting the Approach controllers to try and implement a lot of the delaying action when it could have been done upstream. However, once in the TMA, the controllers can now arrange the aircraft so that they are at minimum sep.

 

Another thing to keep in mind that when you set up your metering programs, you aren't trying to preprogram separation - that will kill your operation. The guys that do this every day have an idea of how many aircraft you can land per hour in given runway config/weather conditions and the idea is to set your acceptance rate very near to the limit for those conditions, because at the end of the day, your capacity is physically limited and there is no point trying to exceed those physical limits. Of course, you guys in the US have some special rules that do help push those physical limits a bit

 

Btw, Rob has seen a bit more traffic than what Sunshine Coast gets... I hear the Middle East is rather popular for air travel these days.