It often seems to happen that if you set an ILS approach for a particular runway and then want to add a STAR, the latter will duplicate one or more of the ILS waypoints.

An example: fly into Lisbon LPPT, runway 02. Select the ILS for that runway (no transition) and then STAR TROI9A. You then have a plan which includes the waypoint PESEX twice, once near the end of the STAR and again, after CF02, as part of the ILS approach. How is that resolved in practice? (Why would a STAR approach duplicate one of the ILS waypoints like this in any case? Surely most times a pilot will choose to add a STAR to an ILS approach, not use the STAR instead of the ILS. They hardly fulfil the same function of course). Does the flight computer ignore the duplicate waypoints, or does the aircraft turn and try to pass the waypoint(s) again? Or do you have to fiddle with editing the plan in the FMC. Or...?

Thanks

The box will fly exactly what is in the box. It’s incapable of thinking.

The star ends at PESEX so should link right up with PESEX on the ILS 02. When you choose no transition you’re telling the box not to connect the two procedures so it puts in a discontinuity and keeps the procedures separate.

PT422 . /+4000
PESEX 180/+4000
- - - discontinuity - - -
PESEX /4000
NETVO

So you either go back and link the two procedures in the arrival page or manually delete the discontinuity.

PESEX is the clearance limit of the TROI9A STAR so if you haven’t been cleared for the approach and you have only been “cleared to” PESEX you’d enter a hold at PESEX as published when you get there.

If you leave the discontinuity in the box you should get some sort of warning as you approach PESEX informing you of the discontinuity. When you get to PESEX with the discontinuity the plane should do a triple click aural to warn you of a mode reversion and switch to HDG / ALT and will fly hdg 025 at 4000 until you tell it to do something else.

That all makes sense, I think, thank you. Only thing is (and the crux of this example) is that the ILS into runway 02 at LPPT runs: CF02, PESEX, (RW02). So if the STAR leads you to PESEX and the ILS approach then becomes active, I guess the plane will head back to CF02 and then try to proceed back to PESEX from there (unless you 'fix' things in the FMC, of course)?

I think that is a flight sim issue.

The charted ILS 02 approach plate doesn’t show a CF02

When you load the ILS 02 it will try to link the approach to the STAR with an APPR VIA PESEX. Which then loads the box with PT422 PESEX NETVO without the discontinuity.

If you do no transition then it loads the ILS with the FAF and one fix before the FAF - for this procedure there is no fix before the FAF - PESEX is the first fix on this ILS procedure and also serves as the FAF. so I’m guessing the flight sim made one up for you that a real FMS database wouldn’t have.

The only time I see a CF waypoint is if I select a runway with no approach. Then the box puts a CF waypoint along the extended centerline of the runway.

But if you leave a CF02 in the flight plan behind you, the box will recognize that you’ve passed CF02 and auto sequence the TO waypoint to PESEX and see that it’s passed PESEX as well and sequence the TO waypoint again to the next waypoint NETVO or RWY02.

Though I have no idea what logic has been programmed for your flight simulator to follow.

I think that is a flight sim issue. The charted ILS 02 approach plate doesn’t show a CF02

I suppose it must be. I use Navigraph, updated every month. I invariably get an approach with 'CV..' and 'FI..' waypoints, ILS or no (9all airports). I don't get 'NETVO' for this approach either...

But if you leave a CF02 in the flight plan behind you, the box will recognize that you’ve passed CF02 and auto sequence the TO waypoint to PESEX and see that it’s passed PESEX as well and sequence the TO waypoint again to the next waypoint NETVO or RWY02

Ah, interesting. That's really what I was wanting to know. I will try out a flight soon and see if that is the case in the sim (X-Plane 11 + a 'Toliss' A321 probably: the Toliss aircraft is certified by Airbus and amazingly accurate (as far as I can tell, not being a real-world Airbus pilot!), so the chances are that the sim will do just what the real aircraft would do).

Thank you very much once again for taking the time to reply.

Martin

Those fixes are called path terminators in ARINC database coding. Think “path to a termination point. CF is a course to a fix, where the path ends.

https://www.icao.int/safety/pbn/Seminar ... 07/D.3.pdf

Downloaded the pdf, thanks.

Martinlest wrote:

It often seems to happen that if you set an ILS approach for a particular runway and then want to add a STAR, the latter will duplicate one or more of the ILS waypoints.

An example: fly into Lisbon LPPT, runway 02. Select the ILS for that runway (no transition) and then STAR TROI9A. You then have a plan which includes the waypoint PESEX twice, once near the end of the STAR and again, after CF02, as part of the ILS approach. How is that resolved in practice? (Why would a STAR approach duplicate one of the ILS waypoints like this in any case? Surely most times a pilot will choose to add a STAR to an ILS approach, not use the STAR instead of the ILS. They hardly fulfil the same function of course). Does the flight computer ignore the duplicate waypoints, or does the aircraft turn and try to pass the waypoint(s) again? Or do you have to fiddle with editing the plan in the FMC. Or...?

Thanks

For that particular STAR in the AIP chart it says that PESEX is the clearance limit and it has a hold. The real FMC might place a hold in there. Clearance limit means you will need to be cleared for example "FROM GODGI via PESEX cleared ILS 02" to actually start the ILS, otherwise you must hold at PESEX.

If you were given "FROM GODGI via PESEX cleared ILS 02" you would arm the approach after GODGI, G/S and LOC would be blue on the second line meaning they are armed, near PT421 you would see LOC* as it turns to captures the localizer, and then LOC when it is captured. The lateral tracking in LOC mode moves away from the FMC and is flying the LOC beam. The duplicate PESEX points in the FMC will sequence without doing anything.

Woodreau wrote:

I think that is a flight sim issue.

The charted ILS 02 approach plate doesn’t show a CF02

When you load the ILS 02 it will try to link the approach to the STAR with an APPR VIA PESEX. Which then loads the box with PT422 PESEX NETVO without the discontinuity.

If you do no transition then it loads the ILS with the FAF and one fix before the FAF - for this procedure there is no fix before the FAF - PESEX is the first fix on this ILS procedure and also serves as the FAF. so I’m guessing the flight sim made one up for you that a real FMS database wouldn’t have.

The only time I see a CF waypoint is if I select a runway with no approach. Then the box puts a CF waypoint along the extended centerline of the runway.

But if you leave a CF02 in the flight plan behind you, the box will recognize that you’ve passed CF02 and auto sequence the TO waypoint to PESEX and see that it’s passed PESEX as well and sequence the TO waypoint again to the next waypoint NETVO or RWY02.

Though I have no idea what logic has been programmed for your flight simulator to follow.

Indeed it does sound like a flight sim issue. The real FM does not insert a duplicate waypoint. As long as the STAR and approach link up, the path is logical with the point not duplicated.

If the STAR and the approach do not link up, you get a discontinuity. In that case either you've put in the wrong VIA, not put in a VIA at all, or the STAR terminates in a "vector" leg, where you'll just be vectored onto the approach.

In some cases, the FM will automatically insert the applicable VIA waypoint, if any. In others not. It is fairly self-explanatory in most cases, though there are places where the STAR and the approach don't link up logically. Yes, I'm looking at you, Jakarta...

The old ILS system at he one side and the new EGNOS/WAAS enviroment at the other side are not really compatible right now.

Woodreau wrote:

I think that is a flight sim issue.

That was my initial thought upon checking into this thread having had some experience with FMC issues in Flight Sim in the past, but nonetheless, it sparked my curiosity about real-world FMC use. I'd be interested to hear what any real-world pilots have to say about the training that goes into using FMC systems on different aircraft and whether there's differences training between systems or simply cursory "here's a weird thing on this one that you'll want to keep in mind..." explanations when you move from one aircraft to another. Basically, any "shop talk" about the ins and outs of day-to-day use might be of interest, but I suppose it might be one of those things that folks who actually sit up front will tell me is yawn-inducing minutiae.

gunsontheroof wrote:

Woodreau wrote:

I think that is a flight sim issue.

That was my initial thought upon checking into this thread having had some experience with FMC issues in Flight Sim in the past, but nonetheless, it sparked my curiosity about real-world FMC use. I'd be interested to hear what any real-world pilots have to say about the training that goes into using FMC systems on different aircraft and whether there's differences training between systems or simply cursory "here's a weird thing on this one that you'll want to keep in mind..." explanations when you move from one aircraft to another. Basically, any "shop talk" about the ins and outs of day-to-day use might be of interest, but I suppose it might be one of those things that folks who actually sit up front will tell me is yawn-inducing minutiae.

They are quite different in some ways. I can vaguely muddle my way around a 777 FM, but no way could I easily find all the items I would need in order to "operate" it like a pilot rated on type .

Same goes for the A330 vs A350. The underlying principles are the same, but the interfaces are very different. It takes some learning and practice before you can use both proficiently.

gunsontheroof wrote:

That was my initial thought upon checking into this thread having had some experience with FMC issues in Flight Sim in the past, but nonetheless, it sparked my curiosity about real-world FMC use. I'd be interested to hear what any real-world pilots have to say about the training that goes into using FMC systems on different aircraft and whether there's differences training between systems or simply cursory "here's a weird thing on this one that you'll want to keep in mind..." explanations when you move from one aircraft to another. Basically, any "shop talk" about the ins and outs of day-to-day use might be of interest, but I suppose it might be one of those things that folks who actually sit up front will tell me is yawn-inducing minutiae.

The FCOMs are good at explaining what the system involves, however they are generally poor at teaching people how to use them. It gave rise to 3rd party manuals like the "Big Boeing 747, 757, 767, 777 FMC User Guide" which is more focused on how to use it practically rather than how the FMC works. Pilots learn how to use the FMC by CBT, then IPT, the SIM, and also line indoc.

Martinlest wrote:

Or do you have to fiddle with editing the plan in the FMC.

Martinlest, yes, sometimes you do, depending on how the procedures (STAR/approach) load into the FMS, based upon transitions, VIAs, etc.

As you can tell from the previous responses, the best "takeaway" I can offer you in this case--and we do this regularly in real world operations--is once you have the procedures loaded into the FMS, carefully scroll through all the waypoints (and you can view them on the ND as well)--this is Airbus--to make sure you have no duplicate points and to ensure there are no "discontinuities," unless you want them for a particular reason. The sequence should be logical and make sense.

Then, of course, once you receive ATC clearance, make sure the flight plan you loaded into the FMS is consistent with that clearance.

e38

e38 wrote:

Martinlest wrote:

Or do you have to fiddle with editing the plan in the FMC.

Martinlest, yes, sometimes you do, depending on how the procedures (STAR/approach) load into the FMS, based upon transitions, VIAs, etc.

As you can tell from the previous responses, the best "takeaway" I can offer you in this case--and we do this regularly in real world operations--is once you have the procedures loaded into the FMS, carefully scroll through all the waypoints (and you can view them on the ND as well)--this is Airbus--to make sure you have no duplicate points and to ensure there are no "discontinuities," unless you want them for a particular reason. The sequence should be logical and make sense.

Then, of course, once you receive ATC clearance, make sure the flight plan you loaded into the FMS is consistent with that clearance.

e38

Spot on. Consistent methodology every time, and cross-checking, will lead to consistent results.

The DIFSRIPP mnemonic is handy for FM (MCDU) pre-departure data entry on Airbus.
- DATA - Aircraft Status. Check database validity, performance factor, and idle factor.
- INIT - Enter data, import winds and check IRS alignment.
- F-PLN - Enter SID, route, STAR and approach. Scroll through all points, checking against the charts and flight plan. Use PLAN on the ND with CSTR enabled for the SID, STAR, and approach.
- SEC F-PLN - Copy the active flight plan into the secondary and adapt as needed. In most cases, I'll put in a return to the departure airport starting from the SID endpoint. Just the approach with no STAR. In the secondary performance APPR page, enter the ATIS data and minimum.
- RAD NAV - Check that the departure runway ILS (if any) is autotuning with correct course.
- INIT B - Enter ZFW, ZFWCG, and block fuel. Check takeoff and landing weights against flight bag app (and later loadsheet).
- PROG - Check cruise, optimum, and rec max altitudes. Set distance reference to the runway or other appropriate point.
- PERF - Enter takeoff and climb performance data.
(- If there are any climb restrictions, go back to the F-PLN page to check that you can meet them given weight and climb derate. Adjust as needed.)

Do these steps in the same order every time and you'll minimise mistakes.

For descent preparation, use the "Top Hat" pattern.
- F-PLN - Check STAR and approach.
- RAD NAV - Check that the ILS (if any) is autotuning with correct course.
- PROG - Set distance to the arrival runway or other appropriate point.
- PERF - Set approach weather and minima data. Set go around thrust reduction and accel altitudes if non-standard.
- FUEL PRED - Check fuel prediction page and adjust data as needed.
- SEC F-PLN - If needed, copy active flight plan and adjust. For example if you expect a runway change enter data for the expected runway.