Jump to content

Cruise Altitude Constraint


Recommended Posts

Hi, planning a flight fro LMFL to LIRA using the following route

NASIK UP856 DIVUL UM728 BTA UL146 ELKAP,

and validating it, I found that there is a constraint in BTA where the max FL is 295 (following the RAD 1411). The I tried to insert a constraint in the advanced page:

BTA FL290.

After computation I obtained the correct flight plan that was validated correctly

-N0436F390 NASIK UP856 DIVUL UM728 RATAP/N0404F290 UM728 BTA
UL146 ELKAP

but the flight log is wrong:

--------------------------------------------------------------------
AWY FL IMT MN WIND OAT EFOB PBRN
POSITION LAT EET ETO MORA ITT TAS COMP TDV
IDENT LONG TTLT ATO DIS RDIS GS SHR TRP AFOB ABRN
FREQ
--------------------------------------------------------------------
UM728 390 117 .77 208/045 M62 3906 2298
RATAP N4243.4 0001 ... -- 118 434 P001 M05
E00906.3 0028 ... 11 174 432 3 375 .... ....
UM728 390 117 3811 2393
BTA N4234.4 0003 ... -- 119 P001
BASTIA E00928.5 0031 ... 19 156 3 375 .... ....
114.15
ROMA UIR************************************************************
-LIRR N4237.3 0002 ...
E00945.0 0033 ... 13 143
UL146 348 075 3798 2406
MOULE N4237.3 0002 ... -- 077 P001
E00945.0 0033 ... 13 143 1 376 .... ....
UL146 290 075 .69 198/040 M44 3722 2482
ELB N4243.8 0004 ... -- 077 405 P001 M01
ELBA E01023.7 0037 ... 29 114 424 2 376 .... ....
114.70
UL146 290 091 .68 200/040 M44 3661 2543
ELKAP N4243.3 0001 ... -- 093 399 P001 M01
E01038.6 0038 ... 11 103 408 2 376 .... ....
290 119 .68 200/040 M44 3622 2582
*TOD N4239.8 0001 ... -- 121 399 P001 M01
E01046.5 0039 ... 7 96 390 2 376 .... ....
As you can see over BTA we are at FL390 and not a FL290 as requested. What was the mistake?
Link to comment
Share on other sites

Hello Andrea,

Here is a default OFP where I set descent one waypoint earlier to be level at BTA:

attachicon.gifcapture_001.jpg

Hi Stephen, sorry but I'm not sure if I understood correctly. What is the process you followed to obtain the result? In which way you set the descent?

I notice that the advanced option to set an altitude constraint is quite a bit wrong because if I indicate BTA FL290, I mean that over that point the airplane has to be at FL290, not that from that point the airplane has to start the descent, also because in this way there is not any chance to determine when and where the airplane could be at the indicated FL. While instead when I estabilish the constraint, the system has to calculate where start the descent to reach the indicated FL over the decided point.

Do you agree with me?

Thanks

Link to comment
Share on other sites

Hi Andrea,

Unfortunatly it is the way PFPX works: you enter the point where you wish to start your descent and not the point where you want to be levelled at.

I suppose it was not possible to program PFPX differently.

It is true that PFPX being only a planner we should use it mostly to calculate fuel and times and I found out that the best way to work with the constraints and to get good results was to start the descent (on the planner, not in flight) well before the point where you have to be levelled at and in that case the fuel would be correct.

I had a post on a similar subject sometimes ago and I understand it is the correct way to proceed.

I wish we could do it differently but it is up to the developpers to amend the program.

Regards,

JP

Link to comment
Share on other sites

Hi Andrea,

Unfortunatly it is the way PFPX works: you enter the point where you wish to start your descent and not the point where you want to be levelled at.

I suppose it was not possible to program PFPX differently.

It is true that PFPX being only a planner we should use it mostly to calculate fuel and times and I found out that the best way to work with the constraints and to get good results was to start the descent (on the planner, not in flight) well before the point where you have to be levelled at and in that case the fuel would be correct.

I had a post on a similar subject sometimes ago and I understand it is the correct way to proceed.

I wish we could do it differently but it is up to the developpers to amend the program.

Regards,

JP

Ok, thanks a lot. I read again the thread you are talking about. Maybe I had to read it more carefully to understand better what was the problem. So now I perfectly understand the situation and the probable criteria with which the advanced option works.

Perhaps it could be a good idea to have an option to impose a constraint in the way we are discussing. Anyway, the strange thing is that I inserted BTA FL290, PFPX (as described in the Thread you indicated) used it as a "start to descend" point but in the ATC Flight Plan, it indicated RATAP/N0404F290 as it was RATAP the "start to descend" point (even if 19NM to descend 10000ft are not enough unless you want to make a sudden 4000ft/min descent). Something is not so clear as it should be.

Link to comment
Share on other sites

Hi Andrea,

I ran the route again applying the FL290 at restriction to RATAP, it passes validation as your in descent.

My restriction entry shown below.

attachicon.gifcapture_003.jpg

attachicon.gifcapture_002.jpg

Yes Stephen, I made another test indicating OKROK and this is the best solution to be at FL290 over BTA

Thanks a lot.

Link to comment
Share on other sites

Helle Andrea,

You are absolutely right, there is something wrong in the logic of the altitude constraint.

I did a FPL EGHI / LFPO. I am cruising FL230 but I need to be at LGL FL190 (French ATC restrictions).

If I enter in the advanced LGL FL190, the ATC FPL (1) is correct but the OFP FPL (1) is not because it is starting the descent at LGL instead to be levelled FL190 by LGL.

To be level LGL FL190 I have to enter in the advanced DVL FL190, then in the ATC FPL (2) I'll be level FL190 at LGL but on the ATC FPL (2) it shows that I would be level FL190 by DVL.

I do not know if we should rise a ticket?

May be Steven would have an idea.

Regards,

JP

post-92552-0-68928000-1415872387_thumb.j

post-92552-0-88655400-1415872388_thumb.j

post-92552-0-98804100-1415872389_thumb.j

post-92552-0-34890200-1415872391_thumb.j

Link to comment
Share on other sites

Hello JP,

From the EuroControl IFPS manual:

EN-ROUTE CHANGE OF SPEED AND LEVEL
(2) Requirements
Changes to the speed and/or level may be indicated in the route field of a flight plan or
associated message submitted to the IFPS for processing; any such change of speed and/or
level shall be associated with a specified point in the route of that flight. Changes to
speed/level shall be specified at each point at which either a change of speed and/or level is
planned to commence.

Link to comment
Share on other sites

Hello Steve,

It is a good thing that I am retired now! Stupid of me I should have remember that it is the point where the change is planned. It is true that I did not file a FPL for some years but if I had to go back to my exams I would be failed.

Sorry again.

Regards,

JP

Link to comment
Share on other sites

Hello Andrea,

The document confirms the requirement to file your intended change of altitude at the point of descent. In you example you have a FL restriction at BTA so any change of level is filed prior to that:

" Changes to speed/level shall be specified at each point at which either a change of speed and/or level is planned to commence."

Link to comment
Share on other sites

Ok, but there is a difference between ATC flight plan and the flight log. Here the problem is that there is a strange behaviour of PFPX. If is correct to consider that in the advanced option we have to insert the point from which the decent has to start (and it could be more useful if it could be possible to indicate the point at which there is the constraint and PFPX could calculate where to start the descent), why the ATC flight plan section indicates a previous point ?

Regards

Andrea

Link to comment
Share on other sites

Hello Andrea,

Perhaps one of the dispatchers will correct this but from the flightplan submission and validation to EuroControl as long as you are descending prior to the FL restriction the requirement is satisfied. In your example descending from RATAP satisfies the restriction and the flightplan is validated.

Link to comment
Share on other sites

Hello Steve,

I did some more tests and it appears that starting the constraints from the planner would not give all the time a FPL CFMU approved and we have to amend the ATC FPL to have it approved.

Anyway the main thing is, as you mention, to have the FL restriction satisfied and your FPL approved and when you are in flight you negociate with ATC to maintain your FL or a DCT or start your descent later or earlier, and so on. Most of the time it worked. I assume today it is still the same despite than traffic is getting heavier.

Regards,

JP

Link to comment
Share on other sites

Hmm, here is my result of setting FL290 at BTA in the advanced tab to meet the required restriction as required by IFPS and the validated CFMU result:

(FPL-AFR164-IN
-B738/M-SDE1FGHIJ1RWXYZ/LB1
-LFML1100
-N0450F390 DCT NASIK UP856 DIVUL UM728 RATAP/N0406F290 UM728 BTA UL146 ELKAP
DCT
-LIRA0053 LIRF
-PBN/A1B1C1D1L1O1S1 NAV/RNVD1E2A1 DOF/141117 REG/FEBRA
EET/LFFF0008 LIRR0029 RVR/200 OPR/EUROSTAR AVIATION VA
PER/C
-E/0143)

post-5872-0-19579100-1416047624_thumb.jp

EDIT: re-planned with FL290 set at BTA

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Privacy Policy & Terms of Use