FP SID STAR changes seem endless

[Tobias Dammers]

It is very common for ATC to change SIDs in Europe, to the point where, in most places, you aren't even supposed to file a SID, but rather just put your first enroute fix, and ATC will then assign you a SID. This is because most European SIDs are runway-specific, so in order to determine the correct SID, you need to know what the active runway is, which you often don't when you file. Some airports also have separate sets of SIDs depending on traffic flow, which in turn may depend on day of week or time of day (for noise abatement reasons), or active runways at nearby airports. The SID will be assigned as part of your IFR clearance though, and is extremely unlikely to be amended after.

STARs and transitions are given during descent, and are equally unlikely to change after, but for the same reasons as SIDs, you don't usually file them, but wait for ATC to assign them.

[Robert Vanderkam]

As OP, I'll point out a couple of things:

- I've been using Flightaware as suggested by someone here for the flight plans (thanks!).

- I can now easily delete or add waypoints in the MCDU after some practice, but the FBW NX does not allow edits to the SID/STAR waypoints (afaik), which seems reasonable. I can usually iron out things since I'm still parked.

- I still file my STAR with the flight plan, and use VATSIM arrival airport ATIS or metar before takeoff to set up the arrival and approach and check that it works.

But If I'm asked to change my approach or arrival on descent, I will try but when things go wrong, there's often nothing to do except disconnect if I don't want to ask the ATC to hold my hand trying to fix a FP with an unfinished aircraft. At least I can fly on VATSIM again. Comments appreciated and welcome.

[Tobias Dammers]

1 hour ago, Robert Vanderkam said:

But If I'm asked to change my approach or arrival on descent, I will try but when things go wrong, there's often nothing to do except disconnect if I don't want to ask the ATC to hold my hand trying to fix a FP with an unfinished aircraft. At least I can fly on VATSIM again. Comments appreciated and welcome.

You can still request vectors to final and tune the ILS freq manually, no?

[Robert Vanderkam]

11 minutes ago, Tobias Dammers said:

You can still request vectors to final and tune the ILS freq manually, no?

Yes, I remember that now. I'll keep it in mind.

[Dustin Rider]

5 hours ago, Robert Vanderkam said:

- I can now easily delete or add waypoints in the MCDU after some practice, but the FBW NX does not allow edits to the SID/STAR waypoints (afaik), which seems reasonable. I can usually iron out things since I'm still parked.

I still haven't made the switch to MSFS2020, so I'm only tangentially familiar with how these aircraft behave in the simulator. Most of what I know is informed by word of mouth or word of forum, and that's where these questions are coming from.

What kind of edits are you referring to? Can you proceed direct to a waypoint that's somewhere in the middle of the procedure? For example, take the POWDR1 STAR; if you've programmed the HBU transition, but ATC clears you direct POWDR, will that work? What if you're still on the procedure over BASEE and given direct POWDR? How about if ATC had you on the LARKS arrival (the adjacent STAR from this direction) and needs to put you on the POWDR arrival, but you're already abeam BASEE, so ATC clears you direct SKEED for the POWDR1? Granted, even in most normally-functioning flight management systems, that last clearance will still require loading up the whole procedure from some transition fix (HBU, DBL, JNC, etc).

On a related note, what navigation instruments come with the Airbus on MSFS2020? It still comes with two NAV radios for VOR navigation, right? Does it also have DME capability? If it does, you might be better served filing a /W equipment suffix and filing non-RNAV routes. That lets ATC know that you're still RVSM-capable, but without GNSS or RNAV. Strictly speaking, this is more of a workaround (since presumably the Airbus does have GPS capability), but it will give ATC a heads up to make sure they are putting you on the correct non-RNAV procedures and routes.

[Robert Vanderkam]

On 1/8/2021 at 7:49 PM, Dustin Rider said:

What kind of edits are you referring to? Can you proceed direct to a waypoint that's somewhere in the middle of the procedure? For example, take the POWDR1 STAR; if you've programmed the HBU transition, but ATC clears you direct POWDR, will that work? What if you're still on the procedure over BASEE and given direct POWDR? How about if ATC had you on the LARKS arrival (the adjacent STAR from this direction) and needs to put you on the POWDR arrival, but you're already abeam BASEE, so ATC clears you direct SKEED for the POWDR1? Granted, even in most normally-functioning flight management systems, that last clearance will still require loading up the whole procedure from some transition fix (HBU, DBL, JNC, etc).

Fingers crossed that I won't run into this for a while. At the moment, I'm really only concerned with being assigned a different STAR while on cruise. If that happens while I'm on the ground, as it does with SIDs, I can see if the ATC changes work on my FMC and then proceed. What goes wrong is that I get "spikes" (ie, leftover (?) waypoints that require a sharp deviation and return to the obvious route) or breaks in the route.

I am not skilled enough to handle those while on arrival, yet, and was wondering if everyone else can. From your and other descriptions, I'd guess the answer is yes. But I was hoping to not have to learn all the skills before flying on VATSIM so I've been trying to prioritise what's key vs what can wait.

On 1/8/2021 at 7:49 PM, Dustin Rider said:

On a related note, what navigation instruments come with the Airbus on MSFS2020? It still comes with two NAV radios for VOR navigation, right? Does it also have DME capability? If it does, you might be better served filing a /W equipment suffix and filing non-RNAV routes. That lets ATC know that you're still RVSM-capable, but without GNSS or RNAV. Strictly speaking, this is more of a workaround (since presumably the Airbus does have GPS capability), but it will give ATC a heads up to make sure they are putting you on the correct non-RNAV procedures and routes.

I'll keep this in mind, but it sounds like something I'd rather not prioritise. I haven't done VOR nav since FS4 in the GA aircraft.

Thanks

[Dustin Rider]

1 hour ago, Robert Vanderkam said:

Fingers crossed that I won't run into this for a while. At the moment, I'm really only concerned with being assigned a different STAR while on cruise. If that happens while I'm on the ground, as it does with SIDs, I can see if the ATC changes work on my FMC and then proceed. What goes wrong is that I get "spikes" (ie, leftover (?) waypoints that require a sharp deviation and return to the obvious route) or breaks in the route.

This sounds like typical behavior for a flight management system under most circumstances. Take my example about already having passed the initial fix on a procedure, but ATC has to change your STAR. In order to load it, you'll likely have to pick some fix on the new procedure that's already behind you in order to load up the whole procedure and select the correct one that is (hopefully) in front of you. Now, most FMS's won't execute a new path until you tell it to, but it sounds like the one you're dealing with will. In that case, all you should have to do is sync your heading bug to your present heading, put your autopilot in heading mode, make the changes and select the new waypoint you've been cleared to, then reactivate your NAV mode. So long as you are able to select the new waypoint ATC gives you, and tell your FMS to go "direct to" you shouldn't have any issues.

Route breaks also happen all the time when you are changing your routing. Once an FMS is programmed to fly a path from origin to destination, any changes to that route will need to include one of two things: new routing all the way to the new airport (e.g. ATC assigns you a new STAR), or some way of rejoining the route you had been issued. The latter example is typical of summertime reroutes for weather avoidance, which I don't think is typically simulated on VATSIM.

I could easily go down a rabbit hole here and explain how new STARs will often times affect and "break" the route that you had programmed to get from STAR to instrument approach for your anticipated runway (and therefore it's typically easier to wait until you've received your runway assignment from the approach controller), but I wanted to see if I'm on the right track for the behaviors you're seeing with your aircraft.

[Robert Vanderkam]

8 hours ago, Dustin Rider said:

In that case, all you should have to do is sync your heading bug to your present heading, put your autopilot in heading mode, make the changes and select the new waypoint you've been cleared to, then reactivate your NAV mode. So long as you are able to select the new waypoint ATC gives you, and tell your FMS to go "direct to" you shouldn't have any issues.

Great. Making notes. And yes, you have the situation clearly described.

Edited January 11, 2021 at 12:22 AM by Robert Vanderkam
Clarity