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Guest noflyzone

T/C T/D Problem

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GentsHere is the flightplan HKJK-HKMOIMSAN.GITNO.CD21.MOV.RW21DEP: HKJK RWY 06ARRV: HKMO ILS RWY 21 (110.10/210)FL300When i run this in PSS, my first fix gets plotted at 27400, and the T/C appears way after the GITNO FIX. I have no idea why. Nor do I see the T/D point.http://forums.avsim.net/user_files/147237.jpgWhen i repeat using LDS-767, everything works fine, and the T/C appears BEFORE the IMSAN fix where it should be, and the T/D after IMSAN.http://forums.avsim.net/user_files/147238.jpgCan you please advise?cheers~mike

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Mike,First of all, the LDS FMC and the PSS FMC are apples and oranges (or SMITH and PEGASUS specifically). The setup is a little different for both.TOC and TOD calculations are based on what altitudes are set in the MCP and FMS (this is obvious). What is not obvious is, if you are in VNAV, what do your legs tell you? In the example you cited above, the TOD is absent and the TOC dot exists. One way this can happen is if you are below the TOD and you are below the next altitude in the descent phase if in VNAV mode. A TOC will always appear if you are below the altitude that is set in the MCP altitude window, despite what the legs page says.Were the MCP altitudes set the same on both MCPs and in what mode were you in? VNAV? If you can answer that, we may be able to narrow down an answer as to what occurred in your particular case.A word of caution about FMCs: They all function a little differently. While things may LOOK the same, they don't necessarily function the same. This is why so much emphasis on conversion training is put on the FMC/MCP, since the 767 logic and 777 logic are quite different. Therefore, I am not surprised that you have two different screens; but one other question? Why were you in PLN mode on the ND? There are few times that PLN is used in flight; most of the time MAP mode in ARC is used. Just curious...you may have had a totally logical reason for being in PLN. Word of caution: It doesn't always give you the true picture.If you can do this again in MAP/ARC and produce the same result, given the points made above, then this merits further investigation and I'd be happy to research it.best,Dave Lamb

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Dave,Thanks for replying.Yes, both MCP ALT were set to FL300 and the FMC's alt on the PERF page were set to FL300. I was in Plan mode using STEP to validate the fixes.. likewise switching to map mode, on the PSS I only see the T/C - there is no T/D..However, after creating a NEW flight, (create a flight, FS2004) and not using a previously saved flight, i found the first fix is input at the proper MCP altitude. So this issue seems related to using a saved flight for some reason. If you restore a saved flight, go to PERF page, enter a new ALT, then set the MCP ALT speed to the same, then go to LEGS page and input fixes, the first fix will not match the FMC PERF alt. So it seems if you want to change the FMC PERF altitude, you're going to have to create a new flight each time and not edit a saved flight. At least that's the behavior i see so far.I will try some more tests and post back shortly.cheers~mikep.s. - altering a speed/alt restriction the 3rd leg or so will cause the sim to hang (but that's a whole different issue).

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I agree with you, after having experienced some very strange behavior in the FMC myself. Most problems should be resolved by resetting the MCP Altitude, but I'd still cross check it against the legs page in the FMC to make sure that the MCP altitude is higher than the leg you are flying in the climb, or lower than the altitude you are flying if descending. If this is not done carefully, it could cause the VNAV to fail, in which case, all you have left is FLCH and V/S. TOC/TOD should still calculate correctly when you fix it as described in your post..but still...cross check it against the FMC altitude before hitting the button.ThanksDave Lamb

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"First of all, the LDS FMC and the PSS FMC are apples and oranges (or SMITH and PEGASUS specifically)."Dave,The LDS FMS is most assuredly Pegasus.

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