Short Trip Cruise Altitude Problems - Still Not Correct

[B.Fatih KOZ 3]

Hi Christian and support team ...

I saw that the topic I opened for Short Trip Cruise Altitude problems are closed and locked , so I'm opening it again 'cause this issue is not solved and/or closed .

PFPX "still" (for more than 6 months) calculating wrong flight levels and forcing users to obey them without any modification option. Development made progress with 1.13 a little bit and now it's gone back with 1.14 ! It was correct at first releases but changed on purpose as you know , and unfortunately not corrected 'till then .

You can read the details and see examples if you wish again with Boeing reference documents and real flight plans here ; http://forum.aerosoft.com/index.php?/topic/75859-short-trip-cruise-altitude-calculation-still-wrong-and-forced/

Today I updated to 1.14 with wishes of seeing improvements but I was upset again and again and again ...

Simply a partly loaded 737-800 is "forced" by PFPX to fly at FL250 for a 210 nm route ... Empty one is forced to FL290 at the same route ! In fact real world planning and Boeing FFPM and QRH offers much higher levels for that distances . So basically PFPX's Short Trip Cruise Altitude Calculations are corrupt and not correctable .

Would you "really" mind fixing this issue or finding a final solution to leave the decision to dispatcher for modifications !

Best wishes

[dougsnow 50]

Then simply lower the cruise altitude! Boeing used to set their short range cruise altitude based on 1 minute of level cruise at the cruise FL. Some carriers will do that and plan that way. Some airlines will set 1/3 of the trip distance as the min cruise distance and set the Crz FLs accordingly, but the Boeing guidance will not change - thats their operational philosophy (usually for pax comfort). For example, at my carrier, we were ferrying an airplane on a short-distance ferry for storage (about 100NMs), and with an empty MD11 it got planned at FL410. Needless to say, the FPL didnt get sent that way, but thats what came out of the FPS.

Like I tell our dispatchers at my worldwide airline when I am training on the flight planning system - do not depend on the flight planning system to CYA (An American euphemism to cover your ass). if you dont like what comes out of the FPS, modify it. Dont sign a bad plan.

For example, I was just able to run a plan for one of my RPLs from LFPG-EDDF our max FL of FL230. I set the Altitude Cap of FL230 which is what our RPL is filed at, and out comes a correct plan.

If you are expecting that specific short range cruise tables from the FPPM are programmed into the aircraft model, they are not.

615 MD11 SEL/KMAS TYPE CI 75 FL230 ROUTE RPL 287 MI

ELEV LFPG 392 FT EDDF 364 FT OAT P01 ETE-0100

N0408F230 RANU3G RANUX UN858 BETEX Z110 RASVO T180 PIPEP DCT

UNOKO UNOK1R

LFPG PLND PAYLOAD 115000 J/S 0 PAYLD 115000

PZFW 371620 MZFW 451300

PTOW 404784 MTOW 508464 MRTW 630500/FLAPS 10/S +9C/Q1028/RW 09R

PLDW 387820 MLDW 491500 MRLW 491500/50/EXT/S +8C/Q1030/RW 07R

---------------------------------------------------------------

FFF / PERF 6.5 PCT CRZ CI 75 US FLAG

---------------------------------------------------------------

FLIGHT PLAN FUEL REQUIRED DISCRETIONARY

TIME/BURN TIME/BURN

---------------------------------------------------------------

TAXI 00:20/ 2.0

TRIP LFPG-EDDF H017 01:00/ 17.0

INTL HOLD 00:30/ 6.6

10 PCT 00:06/ 1.5

HOLD 00:05/ 1.1

TANKER / 4.8

EXTRA 00:10/ 2.2

---------------------------------------------------------------

**********

MIN FUEL FOR T/O * 26.1 *

**********

**********

BLOCK FUEL * 35.2 *

**********

[bcars 23]

Doug:

I , too, have seen both methods ( the 1min cruise and 1/3) Boeing's thought is that the most economical is a parabolic flight path.

A question and an observation with PFPX.

What is the method that PFPX assumes for the short range cruise?

I have had cases in the past ( and some tests run today with 1.14.7) where I plan a short flight ( KLAX-KSAN 110nm ) and by default, PFPX will assign 17,000 This results in a 25 mile cruise seg ( about 1/4 of the trip distance)

This is no matter what I set for the altitude cap , nor whether I select MAX for initial cruise alt. I tried Max Opt ( to ignore the initial ) same thing.

What I normally do is set an unachievable Initial Altitude ( say FL320) and then compute . PFPX will give a popup showing the max achievable. I can then use something close to that. However even if I put a value of 210 in the Altitude Cap, and MAX in the initial and it gives 17000. IF I put 230 in the initial and 210 in the Cap, it still plans for 230. The only way I can control it is to put an actual value in the Initial Altitude.

This is not bad, just unexpected , and like you say, this is a TOOL and not absolute. You have to have an idea about what is reasonable and expected and use the 'suggested' altitudes that PFPX offers as a Guideline. It is extremely accurate most of the time.

[tcasclimb 0]

For example, at my carrier, we were ferrying an airplane on a short-distance ferry for storage (about 100NMs), and with an empty MD11

**********

Please tell me you went full power on takeoff!

[B.Fatih KOZ 3]

Hi Dougsnow ,

I assume you got my post a little bit wrong 'cause I simply want ;

A: To be able to modify the flight levels which is currently "forced" by PFPX !

B: To be able to fly higher levels within short distances according to Boeing FFPM + QRH values

But unfortunately PFPX is not allowing both And the issue is reported more than 6 months ago , nothing done for improvement since then .

I fully agree with you on "CYA" I did not and will not sign an operational flight plan if it does not fit to the situation , that is ok ...

Yesterday I prepared a ferry flight for aprx. 220 nm , offered level was FL390 by the software I use at office , I reduced max alt. to FL350 after checking the vertical profile according to my company regulations , then the software offered FL330 which was ok according to winds (they were better at 330 compared to 350) . But PFPX "forces" FL290 for the same conditions and this is not editable , this is what I do not accept !

So , who makes the error ... In other words , what part of the software deciding and forcing the flight levels ;

A: PFPX

B: Aircraft Performance Files

C: Both

The answer may help us to pinpoint the issue (and maybe the dev team to fix it).

Best wishes

[Flightoff27 0]

Hello!

Are you using advanced tab to modify FLs or you're using main flight planning tab?

I never had such problem and I was able to fly at any desired FL.

With best regards, Alex.

[dougsnow 50]

For example, I just created with an MD11 a 162 mile flight plan with a 100000 lb payload. KORD-KIND along the route DCT EARND DCT ELANR DCT EMMLY DCT JAKKS DCT VHP. PFPX returned as an optimum flight plan at FL250. At FL250 I will cruise at 8 minutes over a 38 minute flight. By entering FL370 in the Init Cruise Alt Box, PFPX happily returns a 36 minute flight; the minute I hit top of climb, its time to start back down.

You're not giving enough details to allow me to figure out what you want. What aircraft type/engine combination, what city pair, what routing, what payload, what fuel policy, did you create the aircraft performance file, did use a template...

[B.Fatih KOZ 3]

Hi Dougsnow ,

Would you mind checking my detailed post with examples ; http://forum.aerosoft.com/index.php?/topic/75859-short-trip-cruise-altitude-calculation-still-wrong-and-forced/#entry541879 [ Post no 8 and further ]

I assume required information was already given , therefore I referenced this post before . [ With operational flight plan examples and results + reference document screenshots ]

City Pair : ADB-AYT / LTBJ - LTAI

Aircraft : B737-800 ( Used template offered with PFPX , no manual input to performance files )

Payload : Used only DOW for ferry test (42800 kgs) , used DOW+17200 kgs for 189 pax

Route : BAPSI UN135 NESIL (shorter route) or KULAR UN131 KOZLU (longer route)

Policy : EU-OPS

Just leave the ALT CAP and INIT CRUISE as default , see the result ... Then you can change the ALT CAP to for exp. FL350 and leave INIT CRUISE at OPT or change it to MAX if you wish ... Nothing changes 'cause at this modes PFPX is calculating the flight according to built in STCA logic.

With this tests, I assume you will see what I'm complaining about .

FL410 + OPT ALT = FL270 ? No according to Boeing specs and docs

FL350 + OPT ALT = FL270 ? No according to Boeing specs and docs

FL350 + MAX ALT = FL270 ? No according to Boeing specs and docs

Simply OPT and MAX selection will give you/change nothing ...

Then you can continue to test PFPX with FL350 at both fields to manually , logically the INIT CRUISE ALT field must be at OPT or MAX ( If "INIT" means "initial" ) we have to change the ALT CAPT field to force the software for a desired flight level . We can discuss the logic later on if necessary 'cause I have to prepare for an eight hour shift

Best wishes

[Flightoff27 0]

Did you try to change FLs in advanced tab? Just try to put your desired FL for first waypoint of your route. And leave all others empty. Also, you can just put your desired FL in INIT ALT. It's just a walkaround.

Regarding problem you described:

I can recommend to check Navdata (not to you, but to team) to check if there are any incorrect restrictions on airway. I met some airways with incorrect MAX levels and allocation scheme.

[CaptainTim 11]

B Faith,

Im not sure what your getting at here... Does this mean you want a FL350 cruising altitude for 5 or 6 minutes??? Or don't?

Years ago I flew on an A330 from London to Manchester (50 min flight time) with half the passengers and little fuel compared to a long haul flight. We cruised at FL260 which was well below what the optimum would be for the aircraft at the time considering its fuel load and payload.

Flight planning requires common sense.

Cheers,

Tim

[BW901 58]

I'm a wee bit confused as well.

I just ran a quick DUB-EDI, 222nm on a 738. Leaving Cruise Altitude/FL as "OPT" PFPX calculated at FL230. Co-incidentally right now on Flightradar24.com the real FR816 is in the cruise between DUB and EDI at FL230.

If I want to plan at a higher level I just hit Re-Plan, type say 31000 into the Cruise Altitude/FL box, hit Compute and PFPX now recalculates at FL310. I haven't touched Altitude Cap or any other variable, just manually typed in my desired cruise altitude.

Jon

[B.Fatih KOZ 3]

@Flightoff27 ;

I know the workaround and wrote this on my last post's last part shortly If you put FL330 or FL350 to "INIT CRS ALT" section PFPX calculates the flight with that level , but logically this is not the way to prepare a flight . A flight planning software like PFPX must handle this without any initial altitude forcing 'cause sometimes the initial altitude must be lower than the optimum altitude ... Payload / SID / ATC Restriction / WX may affect this , so logically the correct field for "desired" altitude must be the "ALT CAPT" one.

After departure aircraft uses optimum settings, if there are no restrictions on the SID (or a part of the route) a/c directly continues to climb to the desired level which is and must be inputted via ALT CAPT field of PFPX (we have MAX ALT section on our professional planning tool). But if there are restrictions on a SID (or a part of the route) a/c climbs up to that limit, then it continues to the desired level.

If you use the "INIT CRS ALT" then you will really force the a/c to climb to that level just after departure. In some cases this may not be possible and this is not the correct way for flight planning

I assume the developer team is well aware of this logic 'cause they are professional aviators, therefore I did not deeply explained all of this at my messages ...

@CaptainTim and @BW901 ;

There may be some ATC restrictions for that city pair or route , as flight dispatchers we face them everyday. So your example flight may be one of them , maybe not ... I'm not experienced on Airbus series maybe that was the optimum for that aircraft. Therefore I'm not telling that the flight level was wrong for your example but professionally I can say that for the same distance a Boeing 737-800 can fly higher with full pax using optimum/documented settings.

I'm a professional flight dispatcher , working for an EU-OPS based airline , planning/dispatching a fleet of +65 Boeings during my shifts (just came home from an 8 hour shift) ... So simply I'm well aware of the common sense you are referring But as I explained above to Flightoff27 , this is not common sense , we have an error here.

According to Boeing documents like "Flight Planning And Performance Manual" (FPPM) and "Quick Reference Handbook" (QRH) , professional examples and dispatcher experience I clearly say that there is problem within PFPX for STCA (Short Trip Cruise Altitude) calculations.

If it is ok for the manufacturer and if the aircraft is capable , 5 minute cruise time is ok for me . I'm not the authority to increase it , none of us are Boeing gives some options for STCA calculations like 1 - 5 - 10 - 15 - 20 mins and there is a line for "minimum trip fuel" , you can check the below graphic (taken from FPPM)

For a 225 nm route and 15 mins cruise time Boeing offers aprx. FL330 ... If you don't care the cruise time and go for "Minimum Trip Fuel" then this offer goes up to FL370 . This is not a claim I'm making , or this is not my personal wish . This is the manufacturer document and planning tools "must" use this info.

The rest like using a higher cruise time , reducing the level due to some ATC restrictions or due to wx "must" be the users choice .

@All ;

This logic was correct months ago during the early versions, PFPX was making the calculations without any problems ... But after some user complaints Christian decided to alter (or maybe tune) the STCA logic and this problem started. If the problem of the users were flying high the answer must be kindly "Then simply lower the cruise altitude!" like Dougsnow said to me

@DevTeam (Replies above also usefull for the DevTeam) ;

Please check the STCA logic of PFPX, if you believe that it is fully compatible with Boeing (manufacturer) specs then check the offered Boeing 737NG performance files of PFPX 'cause clearly we have problem with one of them and this is not corrected for months.

Best wishes to all

[B.Fatih KOZ 3]

5 days passed ... No reply from the dev team or support , also no replies from experienced users helping the dev team Same happened for my earlier posts ...

There is clearly a problem with STCA and no one responds , rejects and/or acknowledges it with proof !

I hereby provide you my evidence with latest Boeing Documents (FPPM , QRH) + Real Life Examples + Professional Experience but nothing happens .

Will continue to write until STCA issue is fixed (which I believe is not a hard task 'cause it was working fine before) .

Safe flights

[Aerosoft Team [Inactive Account] 51558]

I have asked the project manager to contact the developers. As you will understand we are totally unable to solve this issue in our offices.

[B.Fatih KOZ 3]

Hi Mathijs,

I never meant Aerosoft in my posts 'cause Aerosoft is not the developer also for this problem Aerosoft can not give direct support , I know and understand this , we have no problems here ...

Thanks for your valuable input and efforts for the issue we are facing .

Best wishes

[dougsnow 50]

5 days passed ... No reply from the dev team or support , also no replies from experienced users helping the dev team Same happened for my earlier posts ...

Jeeze - youd think you were trying to run an real airline with PFPX. Supporting PFPX isnt my job - its a hobby, and I do it when I can, and want to. I have a life outside of PFPX, and a full time job.

As I said before, the short range cruise tables are not programmed into the PFPX data files for the various aircraft. If you cant cap a flight plan to the altitude you need, then I cant help you. Everytime I need or want to restrict an altitude for any reason, I have been able to.

Guess what, in most flight planning systems (SABRE Dispatch Manager, SABRE Flight Plan Manager, SABRE FOS, Unimatic, Delta's FPS 2,0) the short range cruise tables aren't programmed in either as those are simply manufacturer recommendations. They are not in the Airplane Flight Manual, so they are not mandatory. I thankfully cant speak for Lido (my carrier looked at Lido, then looked away). Maybe Lido does, but since the short range cruise tables do not have an equivalent data format in the SCAP files, or the BPS OUT files, or the Airbus PEP outputs, they are not loaded into most flight planning systems.

If I want to create a flight plan at 10000 from LFPG all the way to UUEE, or any other city pair, I have been able to.

[B.Fatih KOZ 3]

Dougsnow , first of all please calm down ... If my previous post (or posts) made you feel sad or angry , I'm sorry for that 'cause I did not want to do that .

You are trying to help , I understand that well 'cause I'm doing exactly the same to my friends ... But unfortunately your attitude is a little bit "hard" . Maybe you are reading fast to help more people , maybe you do not have enough time or maybe I'm not able to explain the situation correctly .

I also used some other flight planning systems in real life , some had good calculations for short trips some not . All of them allowed manual modification and this is why we work as planners/dispatchers [ This may surprise you but I too have a life outside FS and PFPX ]

Developers of PFPX most probably used/using Lido for their real ops . I'm not telling that Lido is perfect , but at least it can calculate the short trip flight levels good for Boeing NG's . Maybe they had it programmed , maybe it is a user configuration done by request I do not know .

* If you are only helping users it's ok , but if you are being a bridge between users and the dev team I only expect from you to pass this problem to dev team . [ After reading your last post , I think you are only helping users ]

* I did not asked for your help , you asked for details and I provided them ... Then you decided not to help or you do not have any answer/time , this ok . You can simply write this with some simple words like "I can not help you more" ,then I can only say "thank you" .

PFPX - Professional Flight Planner X - is a new and innovative flight planning tool developed by real-world pilots and dispatchers.
It's a valuable and realistic addition to your flight simulation experiences, enabling you to create professional quality flight plans similar to those used by real-world airlines.

This is the PFPX introduction ... You can simply read the developer's claim above . They said that PFPX is a "valuable and realistic" add-on for creating "pro. quality flight plans similar to real-world" ones

I followed the development phase , waited for a long time , read the improvements after first release then decided to "buy the usage rights" of this software . So I'm just a simple "customer" for the dev team and Aerosoft . I paid for this software (most probably will pay for next years server subscription) and want to use it without errors or with minimum and acceptable errors as possible 'cause PFPX claims that it is a realistic tool .

So if the software is not working as told or as advised , I think I have the right to tell it (to developers and other forum users).

If the developers is not reading/responding to our posts, then why we have this so called "Official Support Forum" ? [ Change the title to "User To User Support" and leave official support only to tickets , that would be fine then ]

Thankfully I'm not the only person complaining about the flight level issues of PFPX , some other users are writing too . Maybe they are not professional flight dispatchers like me and they do not see the logic behind the calculations , but at least they see the results and asking about it .

So I again thank you for your kind efforts and all valuable replies to this forum ...

I will wait for an official response to my ticket or to my posts .

* Just a simple question ... If the STCA tables was not implemented in PFPX + Performance files , how it was able to calculate them before ?

* PFPX was able to do good STCA calculations before , but for more than 6 months it is not ! This is the problem ... [ And I have a support ticket for this . Replied as solved but it is not ]

Best wishes

[ BTW : For an official improvement , I know I'll have to wait until next release ]

[BW901 58]

B.Fatih KOZ,

I wasn't going to post but you have made some sweeping comments like "This is the manufacturer document and planning tools "must" use this info". With respect I beg to differ. These are not limitations and it is for the user/operator to decide. Your airline may have a particular policy which works for you, but because others may take a different view it does not mean they are wrong. There are 737NGs airborne now operating short 180-250nm sectors at the lower altitudes which PFPX plans when OPT is selected.

25-odd years ago before we had the benefit of accurate computer analysis of optimum profiles for each sector I recall a chat with our Chief Pilot over a 2am after-duty beer. Part of the conversation was "go higher or lower on short sectors?". His view, which I believe is as equally valid now as it was then was that just because the aircraft is capable of doing something doesn't mean that you have to do it, or that it is worth doing. A ballistic profile straight up and down which some of our skippers were keen on was not recommended. Fuel is not the only factor in running a profitable airline (and yes I am pleased to say the outfit I work for consistently turns a profit), and going high is often long-term not the most efficient way to operate, but that's way off topic for a flightsim orientated product like PFPX.

I guess you are looking for some way for the user to define their own altitude policy.......hold on a second..... isn't that possible by entering your desired cruise altitude instead of just selecting OPT or MAX? For a topic which has a 2-second workaround that gives the user control over PFPX's calculation this is now a remarkably long thread!

Jon

[B.Fatih KOZ 3]

Dear Jon,

I agree on your thoughts ... Yes these are not limitations and we can fly lower if we wish , there may be different factors for choosing low levels on short hauls . ATC Restrictions , Weather , Pilot/Dispatcher Decision , Company Regulations etc. may be one of them and I personally accecpt/understand any of them with respect.

Boeing makes the calculations and "offers" a usage method , users can change it if they are in official limits , not the planning tools. Like the factors above, hereby the user is and must be the deciding factor and no one must force the user to fly low or high. This is why I'm saying planning tools "must" use Boeing (or manufacturer) info.

In our simulator environment cost is not a factor, we can refuel / repair our aircraft with simple clicks without any cost (expect some tools making virtual economic calculations for FS) , so for us flying low or high does not mean much on total cost of the flight , but for a real airline this is a big and deciding factor with many others as you know . Maybe this is a habit which I gained from my daily job but if I can spend less fuel for a route , I choose to go for that option .

We are trying to simulate the real ops therefore we need "near" accurate calculations I suppose , this is why we all paid for PFPX (+ TOPCAT) ... Otherwise we would not need them at all , just fill the tanks to the limit , open the throttle to full and fly

Yes, simply I'm looking for the best way to "decide" the maximum altitude for a flight , not "forcing" it . I explained the logic behind this above ( ALT CAP and INIT CRS ALT field difference ) ... Also the altitude selection process is explained within PFPX manual page 51 and 52 ;

Normally, PFPX plans an initial climb to the optimum flight level (OPT) based on the selected aircraft, cruising altitude restrictions, weight,
temperature, cruise speed, etc. If the MAX value is selected, an initial climb to the maximum allowed altitude is scheduled.
 
Note: If a Cruise Altitude/FL is manually entered a climb to this altitude is scheduled, irrespective of any airway flight level restrictions
and the Step Climb field will be disabled. Further level changes can be applied on the Advanced/Speed/Altitude tab.
 
The Altitude Cap value will normally not be modified. If you wish to specify it, the resulting vertical flight path will be restrained to the value
entered. This can be useful on certain routes not allowing to be planned at a higher level or for technical reasons when an aircraft is not allowed
to exceed a certain altitude.

Anyway, thanks for your thoughts, input and reply (I'm sorry to "steal" your time) ...

Best wishes

PS : Edited last wto lines , somehow it was missing in the first post

[FlightSimSoft.com 283]

Dear Mr. Koz,

As Doug stated in his earlier post, Short Trip Cruise Altitudes are not a requirement for flight planning, nor are they incorporated in the performance data files – as in real world programs.

PFPX does – upon latest release - its own STCA calculation, based on a cruise portion of around 1/3 of trip distance. The algorithm used so far was pretty good, but showed some deviations in strong head/tailwind conditions
Therefore, I’ve now improved the code to base STCA on Air Distance instead of Flight Plan Distance.
This gives significantly better results.

One thing I can’t understand in your posts is your claim that PFPX doesn’t let you choose a flight level and you are forced to use a level you don’t want to.
That’s not true: If you are not satisfied with the one proposed, you can always override cruise altitude by adjusting the ‘Initial Cruise Altitude/FL’ field in the aircraft tab.

Brgds,

Christian Grill

[B.Fatih KOZ 3]

Dear Mr. Grill ,

Thanks for your kind and detailed reply to the topic ... I'll wait for the improvement and from your comment I assume PFPX's STCA calculations will be much better according to Air Distance .

For the "forcing" issue I explained my thoughts about the usage of ALT CAP and INIT CRS ALT sections , currently I know the usage of INIT CRS ALT field ... As the manual clearly states , we are told to use the ALT CAP field for this kind of level adjustments not the INIT CRS ALT (and I personally think that this is the correct usage) .

If you can arrange some free time , maybe you can check and change the ALT CAP fields priority , then we can use it for STCA situations too

Safe flights and thanks in advance for all your efforts .

PS : Is it possible to change the "1/3 trip distance" or "1/3 air distance" to a user selectable value like "5 mins" , "10 mins" , "15 mins" , "Minimum Trip Fuel" etc. in future versions ? Maybe a drop down box at the aircraft database/edit screen or as a general setting for the software itself , so we can adjust it if necessary ?

[FlightSimSoft.com 283]

We´re thinking about an option to define short trip cruise altitude by a percentage of cruise distance (e.g. a value of 33% would mean a cruise portion of 1/3 of air distance). This will be implemented in one of the next releases.