OnCourse Software

Whatever you try, you can't relate on PF3 to get you down in a normal manner.
If you just let the AP fly it always gets it right, PF3 never.
It is so annoying, if it wouldn't be for most other parts are working more or less correctly I would have given up on PF3 long time ago.
Sorry, I know, not my friendliest message but I have to get it out my system.
If any user here actually manages to land an airliner like FBW a32nx correctly with PF3, I beg you, let me know how you achieve this, really.
Cheers,
Luc

Hi Luc,

I'm sorry that you are experiencing these problems.
The FMC will always be able to position an aircraft correctly for landing as it is constantly recalculating an 'ideal' flight path based on the flight plan.
PF3 is emulating real ATC, so issues altitude and speed instructions that need to be used to constrain the FMC's current 'thinking'.
It is certainly possible to have them work together, but it does take a bit of effort to set it up correctly - I have managed to do it successfully.
I will try to find a recent flight plan that shows how to achieve this, otherwise I will check out a new one and post it here with details.

Cheers,
Martin

Hi Luc,

I hear your frustration but I'm pleased you haven't given up on us as we really appreciate your concise feedback, which helps us tremendously in tweaking PF3 to (hopefully) make it even better.

Now, let me mention a few things here. Firstly, PF3 is not a flight planner nor is it an FMC emulator, it's an ATC program. As in the real world PF3/ATC has no idea what your FMC is indicating, the controllers main aim is to get you down safely without bumping into anything or anyone. That said, in the real world most experienced controllers would roughly know when you need to start your descent and they would give you a 'descend to xxx, when ready' and that would usually come before your actual TOD. As I say though, that's through experience because they are handling so many flights and are used to where a particular aircraft type normally begins a descent. PF3 will give that same command if your flight plan indicates a descent before your actually TOD, as it has calculated it, which again may not be what your FMC actually states.

Me personally, I'm a really lazy simmer and it's a good job I'm not nor ever was a real world pilot. Due to most of my flights being for testing purposes I really don't have the time nor the inclination to configure the FMC, so I NEVER use it and only fly via the AP. Now, I'm not suggesting for one moment you should do the same, I just want to make a point here so please bear with me.

I will always hand fly (usually the PMDG 737) during takeoff and up to the point where I'm given the 'resume own navigation' command from ATC. At that point I turn on the AP, HDG, ALT and SPD and always use VCP Mode 3. In addition I have a routine in PF3 (that's only active on my machine) that simulates LNAV, and that works right up until I reach my last waypoint where I will then be handed off to Approach. So all that time my VCP and the AP handle everything for me, according to my flight plan for the LNAV and ATC for my climb/descent/speed.

I can honestly say, hand on heart, that I never, NEVER have a problem in being too high or too low for any flight I've done over the many years since the release of PF3. I'm not saying it's perfect, especially for those experienced simmers who wish for as much realism as possible.

So the next time you have such a problem, and each time you have such a problem, please attach your log so I can check it out. If there's anything I can do to help improve things you know I will do so.

Thank you

SkyCamel wrote: *

Thu Dec 14, 2023 3:31 pm

If any user here actually manages to land an airliner like FBW a32nx correctly with PF3, I beg you, let me know how you achieve this, really.

It is very unlikely PF3's descent profile will match that of your FMC. Each aircraft or FMC has its own flight-path angle used for calculating descent.

I load the flight plan in my FMC and then (before connecting PF3) adjust the altitudes on the PF3 flight plan page to closely correspond with the altitudes in the FMC. This puts the two in fairly close agreement. This is only necessary for the descent phase, not the climb. Remember that when you adjust an altitude on the flight plan page, the other altitudes are NOT automatically adjusted, so you will also need to adjust the altitudes of any XXX waypoints that occur during your descent. Hover your cursor over the waypoint names to see a popup showing the distance to adjacent waypoints, and adjust the altitudes of the XXX waypoints so you have a reasonable descent profile (a good rule of thumb is about 30 miles for 9,000 ft of descent). If you want to start down sooner, adjust the altitudes so you leave cruise earlier. If the altitudes on the flight plan page have you descending 10,000 feet in 10 miles, that is what you will get, so review the altitudes for the descent phase carefully before saving.

I'll throw out a related but 'easier approach to VNAV. ATC will normally give a crossing restriction..."cross XXX at FL200" or "Descend via the XYZ arrival" (which would contain the crossing restrictions). I look at the arrival char and determine two things: 1) where the enroute decent should start to meet restrictions and 2) what is the final altitude for the arrival (typically its listed and if not I use 6000MSL). Then i set all the PF3 altitudes to the final altitude after the initial decent point. That way PF3 will either progressively step me down or just give me the final altitude while I let the plan fly VNAV. I also look at the arrival and remove way points after big divergent points - example...going into KPHL the arrival goes to a spot and then can branch depending on the landing runway - i remove the branches so that if PF3 wants to send me to a different runway i can plug it into the FMS without having ATC telling me i'm off course because the preplanned route now goes to the wrong runway.

All,
thank you for your comments and insight. It somehow motivates me to continue getting things right.
In the next days/weeks I will try to figure out what goes wrong with the descent so you might get some radio silence from my part.
Before I do I would however make some general remarks;

- It is still my(!) perception that the whole TOD and descent changed for the worst in the last few Beta releases. I have the honest feeling that, while I still had issues before, they got worse. Again, that's my perception, other users might have an other feeling about this.

-I understand that PF3 is not a flight planner or a FMC emulator, nor do I expect it to be. However it should somehow respect the FL which are indicated in the Flight plan. My flight plans are made by Simbrief and based on my aircraft profile (fbw a32nx) So it will give me the route and the FL inclusive taking into account the FL constraints on that route. These FL are indicated in the FP I submit to PF3. So why and which corrections should I make into the FP3 flight plan if all the waypoints have their FL as calculated by Simbrief? It doesn't make sense to me.

- When loading the Flight Plan into PF3 I get remarks. Now, that I get waypoint too close to departure or arrival airport I can understand.
But yesterday in a flight I got remarks "waypoints too close"? Yes, they were like 5 NM apart, but, in the middle of my cruise with a few waypoints before and after with the same FL. So who cares that they're close? Of course I can just ignore that remark but then you have to go into the FP and go and figure out what's the issue when there's none.

- When loading a flight plan it's based on the departure and arrival runway. Of course, as in real live, those can change, understandable.
As far as the departure is concerned there's not really an issue. However, for the arrival runway that's another story. Yes I can adjust the route in my MCDU and fly that, but I can't make any changes in the FP I loaded into FP3. So when I get an opposite runway I will fly a totally different route with waypoints not included in the preloaded FP into PF3, so how does FP3 then make sure that I'm descending at the right FL?

- After doing some thinking about the last flights where I had issues I came to realize that it's not so much the TOD which gives problems but the descent path cleared by FP3. Again, the flight of yesterday, I got clearance (TOD) to descent from FL290 to FL260. But then I'm "hanging" there for some forty odd NM before I get the next FL. Why, I don't know. Doesn't seem useful to me to let me fly 3000' lower for such a long distance. So I feel that PF3 gives me clearance to get to the next FL way too late. And that happens in 90% of the flights I made. Maybe PF3 should give clearance for the FL which are two or three waypoints ahead? I can take care of the descent path to the next cleared FL as long if it's not exceeding my max descent rate for the AC I'm flying.
Also, I have to concur with @Sabretooth78, since a few Beta releases back, I never get the instruction "......when ready" which I actually always got before.

@Dave, in my head it's all simple and straightforward but please, rest assured, I know it's far from simple and I admire your programming skills.
I'm not a programmer and I don't know anything about the PF3 code so all my comments are based on my guesswork, reality might (will) be way different.

Cheers,
Luc

I guess the log speaks for itself.
Cheers

Hi Luc,

I have just successfully undertaken a test flight under FMC control using the flight plan that you provided earlier, including a correctly initiated descent.
I will write up exactly how I set it up as it is definitely not just a case of simply loading the flight plan into PF3, it does require adjustment.
Unfortunately I have commitments tomorrow, so it may be a day or so until I am able to provide full details, but I will do it as soon as I can.

Cheers,
Martin

pointy56 wrote: *

Thu Dec 21, 2023 6:14 pm

it is definitely not just a case of simply loading the flight plan into PF3, it does require adjustment.

And that's exactly what is so disturbing to me. Why should I start adjusting something which is made for and is perfectly correct
for the aircraft I'm flying? The FP I'm loading into FP3 is made by Simbrief and based on the aircraft I'm flying.

Cheers,
Luc

SkyCamel wrote: *

Fri Dec 22, 2023 6:45 am

pointy56 wrote: *

Thu Dec 21, 2023 6:14 pm

it is definitely not just a case of simply loading the flight plan into PF3, it does require adjustment.

And that's exactly what is so disturbing to me. Why should I start adjusting something which is made for and is perfectly correct
for the aircraft I'm flying? The FP I'm loading into FP3 is made by Simbrief and based on the aircraft I'm flying.

Cheers,
Luc

Hi Luc,

You're correct, the log certainly speaks for itself. Yes, you created a flight plan using SimBrief which included the departure and arrival procedures. In my opinion the altitude set for KERKY seems a little high to me but then I'm no expert. PF3 actually reduced that from 9200' to 7000', as you are still using the default setting for descent profiles. Had you used the medium setting KERKY would have been set to 6000' and using the long option it would be 5000'. All of which are within the Max/Min allowed, which are 9000/4000 respectively.

Nevertheless, you decided to completely disregard the STAR and went off on your voyage of discovery, way before the entry point to the WODY3B transition. Why would you want to include a STAR and then go off in the opposite direction? Obviously PF3 had to play catch-up and work out where you were going, eventually it gave up and instructed you to proceed to KERKY and descend to 3000', as you were still at about FL140.

Martin has already posted that he was able to use your flight plan without any issue and will be explaining exactly what he did to accomplish it. Unfortunately he's unavailable today but I'm sure he will post his full findings as soon as he can.

Please see below the track of your approach