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NavDataPro: STAR Altitude & Speed Restrictions

Started by MRFarhadi, Thu, 24 Nov 2022 01:31

MRFarhadi

Hi,

I was messing around with the NavDataPro data cycle and found something odd.
As I recently switched to NavDataPro, I was interested in how accurate the data is. So I loaded up LTFM STAR ERSEN2A for ILS Y RW36 and observed the 280 knots and FL270B restrictions were missing from the F-PLN. I was thinking about emailing Aerosoft about the issue, then I discovered if I insert the same STAR and APPR in RTE 2 with no performance figures, routes, or any previous departure procedures (just flat-plain STAR and APPR in RTE 2 with nothing else), the restrictions were present and the data was intact, with all the bells and whistles of the arrival procedure.

Is this something to do with how Aerowinx handles FMC stuff, or is it on Aerosoft NavDataPro?


Best,
Reza


Edit: Also checked with EHAM NORKU2A, EEL1A, RKN2A arrivals. All their initial altitude constraints, if there are no discontinuities in the previous leg from the start of the STAR, do not appear on the legs page nor are respected by FMC. In other words, the speed/altitude restrictions for the first leg of the STAR, are only forwarded from the database to the flight plan when the last waypoint of the flight plan legs is not common with the start of the arrival procedure, resulting in a flight plan discontinuity.
Mohammadreza Farhadi

Hardy Heinlin

#1
Hi, this involves two aspects:

First, as far as I see, ERSEN2A was changed in cycle 2207, and the constraint at ERSEN is just FL270B, with no speed constraint.

Secondly, the missing constraint is an intentional effect in PSX. It's not related to the database.

The effect is this: Say, ERSEN is the last waypoint in your route and an arrival is not entered yet. And there is no constraint at ERSEN. Now you select ERSEN2A on the DEP/ARR pages: The FMC will not add another ERSEN. It will keep the existing ERSEN. And that has no constraint.

If ERSEN is not the last waypoint and you then select ERSEN2A on the DEP/ARR pages, you will get the ERSEN from that STAR along with the FL270B constraint, and with a disco before ERSEN.

Edit: Now I see your edit; you have noticed the logic already.

Maybe I should modify this logic. I'm open for a discussion. I'm not sure if this logic is FMC version specific.
The reason for the current logic is this: If you manually entered a constraint at the last waypoint (e.g. because instructed by ATC), and you then select a STAR that has no constraint at its first waypoint, this first STAR waypoint would then delete you manually entered constraint, and this deletion might not be desired.


Regards,

|-|ardy


MRFarhadi

Dear Hardy,

First of all, thanks for the thorough explanation.

Secondly, I've checked with the latest database from Lufthansa Syetem's LIDO effective November 24th 2022 and also with the Turkish AIS through Eurocontrol's EAD, and both still do have the 280 knots speed restrictions over ERSEN (As LIDO is copyrighted, I can send you a screenshot if you please; Just send me an email).

Lastly, the logic seems kinda logic  ;D
I do understand your point and this looks to be fine. The only problem one might encounter is the necessity of "Manual Reversions" a.k.a. editing the flightplan which when selecting an Arrival or Approach, seems redundant or even misleading (let's just say: not-foolproof  :D ). I've never witnessed a Boeing FMC in action and believe experiences from real-life 747 pilots can be beneficial to the discussion.

As Always, thanks for keeping the PSX community up and running!

Best,
Reza

Edit: Is it possible to only implement this logic (that the FMC ignores the database restrictions if there was already a point, let's call it ERSEN for the sake of the example we had been discussing) only and if only when there was a previous altitude+speed constraint before inserting an arrival procedure?
Mohammadreza Farhadi

Hardy Heinlin

Quote from: MRFarhadi on Thu, 24 Nov 2022 10:49Edit: Is it possible to only implement this logic (that the FMC ignores the database restrictions if there was already a point, let's call it ERSEN for the sake of the example we had been discussing) only and if only when there was a previous altitude+speed constraint before inserting an arrival procedure?

I just had the same idea: If the existing last wpt has no SPD and no ALT constraint, the FMC's initial procedure fix should copy its entire constraint to that wpt.

But I don't know if the real 744 FMC uses the same priority logic. PSX should simulate the real FMC, of course. So we need to clarify this first.

Re LTFM: As I had to test the new Navburo version yesterday, I got a chance to test the next Lido cycle 2212, and that had no SPD constraint at that point. The ERSA2A record's "last change" data is 2207.


Regards,

|-|ardy

MRFarhadi

Quote from: Hardy Heinlin on Thu, 24 Nov 2022 11:53Re LTFM: As I had to test the new Navburo version yesterday, I got a chance to test the next Lido cycle 2212, and that had no SPD constraint at that point. The ERSA2A record's "last change" data is 2207.

Just to make sure, by ERSA2A you meant ERSE2A? I'll be happy to send you the terminal charts regarding the latest LIDO cycle 2247, effective Nov. 24th until Dec. 14th.

Quote from: Hardy Heinlin on Thu, 24 Nov 2022 11:53I just had the same idea: If the existing last wpt has no SPD and no ALT constraint, the FMC's initial procedure fix should copy its entire constraint to that wpt.
But I don't know if the real 744 FMC uses the same priority logic. PSX should simulate the real FMC, of course. So we need to clarify this first.

Awesome! Thanks.
Mohammadreza Farhadi

Hardy Heinlin