Vertical profile has gone in MD-11 during the flight

[cniedzi 0]

Hi,Today I found the vertical profile in FMC has became blank during the flight; every computed altitude was blank, it was only manual constraints. Moreover, FMC TO/APPR page was completely blank (for example no landing speed).Is this issue a consequence of any action I have done? Is it possible to recalculate a vertical profile?RegardsCzarek

[Guest PPSFA]

From what I have seen, thats an indication you missed something required in the FMC, check the pages to be sure all 'boxes' are completed.JayXPPro SP2FSX SP2AMD64 FX-60 Dual Core 2.61 GHz8800GTS-640 megs2 Gigs Kingston RAMFEX-GEX-UTUSA-FSGenesis-and a bunch of other stuffComputer optimized by www.fs-gs.com

[cniedzi 0]

FMC was completely initialized, vertical profile was correct during takeoff and a part of the flight.R.Czarek

[mfrantz 45]

Czarek,By "blank" you mean that the predictions on the F-PLN page (altitude, speed etc.) were replaced by dashes? If this happened during flight this means that for some reason the FMS was unable to calculate predictions. There are some cases that this can happen, but I can't tell what happened if I don't know the exact flight details. In general this will happen if you sequence your destination (except when initiating a Go-Around with a missed approach path defined), or if you are asking for an "impossible" vertical profile calculation that can occur from some change in the flight plan you made (e.g. you are 2NM form destination at FL350).

[cniedzi 0]

Hi MichaelYes, they were dashes, but now I do not remember the circumstances when the issue has occured. R.Czarek

[Guest milliotseb]

HI,Yep I already had it on a glasgow heathrowI had to change the arrival (change runway) but I was too close of the arrival.After that, profile doesn't work anymore. I had to set alt and vspeed by handSame for auto approach speed (according to flaps). I had nothing calculted in approach performance mcdu screen . Finaly I had to set back cruise altitude and all was working well afterSo if it occur again, look to your init page and see if all is filed.

[cniedzi 0]

Hi,As far as I remember there was a very low value of CRZ LEVEL on INIT page (ca.FL 030).R.Czarek

[cniedzi 0]

Hi,The situation was repeated again when I was headed by ATC near the airport. So, is possible to read the Vapp when TO/APPR page is blank?R.Czarek

[Shmiffy 0]

Hi Guys and in particular, Mr. Frantezkakis (sorry if i screwed up the spelling!)This has occured to me too. The situation is thus;1. FMC Fully initialised, as it is for every flight, and the nearly 200 hours i have 'On Type'2. On Climb out from EGKK en route KLAS, i was asked by ATC if i could descend for a traffic issue, to which i duly complied. 3. New altitude entered into the FCP and the ALT Knob was pulled to initiate the descent to the new FL, i think about 4000 Feet below. 4. When clear of conflict, ATC cleared me to climb back to initial cruise, at this point i wind the altitude back up to about FL320 or wherever it was supposed to be, and i hit the PROF button to re-engage the FMS altitude management..... Nothing (cant remember the exact warning message).5. Investigation of the cruise altitudes within the MCDU reveals that the altitudes are now blanked, and it will not let me input any new alts, both 320 and 32000 were tried. From what i can tell, it seems that the FMC is assuming that with any descent, the actual descent phase has begun. I have not tried this yet with any transits through Metric Airspace, so i cannot confirm that the problem also exists when descending as part of a planned step down for metric compensation.hope that you PMDG guys are able to shed some light on the issue. CheersPaul

[mfrantz 45]

Paul,Paul, If your are in CRZ phase before reaching the T/D and lower the FCP to an altitude below you and then pull the FCP altitude knob this is what will happen:- PROF mode, if engaged, will be disengaged (since you pulled the knob)- Descent will be initiated. - Flight phase will become descent, the active PERF page will become DES, the CRZ LVLs will be dashed on the F-PLN INIT, the VDI will show on the ND.- The FMS will assume this is an "early descend". If you are on FMS speed mode a DECEL* prompt will appear on LSK 1R on the F-PLN page to give you the option to reduce speed so that the deviatation from the vertical path is minimized.In case you didn't intend to make an early descend, but this was just a flight level change for traffic or transition to metric airspace, this is what you have to do:- On the F-PLN INIT page enter at the CRZ LVL field the altitude you have dialed on the FCP. Actually even if you enter a lower altitude, it will be changed automatically to the FCP altitude, so a usual trick is to just enter "1". - If you do that while you are still descending the flight phase will remnain DES, but as soon as you level-off at the FCP altitude it will revert to CRZ and a new T/D will be calculated.- If you do that while you have are already captured the FCP altitude, the flight phase will immediately revert to CRZ.In your case this happened during the CLB phase, but still the same logic applies. While descending or while levelled at the FCP altitude, set the FCP altitude as a CRZ altitude to bring back the CRZ phase. Once the CRZ phase is activated, you can revert to the CLB phase by setting a higher CRZ level, and then raising the FCP altitude.

[cniedzi 0]

Thx Michael for your explanation.But I did not catch why the vertical profile has gone? During descent (normal or early) it still should be present.R.Czarek

[Shmiffy 0]

Hi Michael:Many thanks for the response. That makes sense now. I shall give that a go in the next flight if i can.As an aside, with Step Down's or when dealing with metric FL's would the Cruise Alt's input change at all? IE, with a UK/US flight i might enter 300/320/340/360/380 to give the FMC something to calculate, whereas with a flight that terminates or transits Metric space, how could that be input? In feet throughout? ie 320/330/340/331/360?CheersPaulCzarek:Regardless of when you descend, be that 6000 miles from DEST or on top of it, the FMS convinces itself that you wanted to start your descent that early, and consequently switches the flight phase to DES. As you understand from Mike's post, the 'fix' for that in FMS terms is the procedure described above.CheersPaul

[mfrantz 45]

>As an aside, with Step Down's or when dealing with metric FL's>would the Cruise Alt's input change at all? IE, with a UK/US>flight i might enter 300/320/340/360/380 to give the FMC>something to calculate, whereas with a flight that terminates>or transits Metric space, how could that be input? In feet>throughout? ie 320/330/340/331/360?Paul,Flight level entries on the F-PLN INIT page (and in general all altitude entries on any MCDU page) are always in feet. The FEET/METER toggle button affects only the FCP altitude wiindow display.

[cniedzi 0]

>Czarek:>>Regardless of when you descend, be that 6000 miles from DEST>or on top of it, the FMS convinces itself that you wanted to>start your descent that early, and consequently switches the>flight phase to DES. As you understand from Mike's post, the>'fix' for that in FMS terms is the procedure described above.>>Cheers>>PaulThx Paul.My case has happened during approach (ca. 7000ft), so descent phase was already activated. My question is if the altitude predictions in f-PLN page should be dashed in this case?RegardsCzarek

[Shmiffy 0]

Michael:Many thanks for the response. Much appreciated! :)Czarek:If there are what is known as a Constraint within the descent IE AT 2000ft; AT OR ABOVE 2000 FT; AT OR BELOW 2000FT, then they should show up in the F-PLN page. I havent really checked, but i would imagine that there are occasions where any alt predictions may be dashed. As a general rule though, there should be alt predictions for each waypoint.Could you post a screenie of the MCDU page in question, i think i may be a touch confused about your exact meaning :) CheersPaul