FMC comparison

[jimjones]

These are personal observations made with my own PC and software, for the purpose of getting the opinions of those that know(pilots or otherwise knowledgeable persons) of the real life actions of the FMC in these planes as to which is more correct or if they are both correct.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
<o:p></o:p>
Captainsim 757&767 FMCs<o:p></o:p>
<o:p></o:p>
Once The FMC is programmed and the path and profile computed, the MFC altitude window must exceed the cruise altititude.If not the path/profile will not be followed. Once initiated the flight meets all the speed, altitude and waypoint objectives without manual intervention (ie automatically). Simrate can be as high as 4X most of the flight without getting far off course. At steep turns NORMAL sim rate works best to follow the longitudinal path. Experience has shown that the ILS frequency is auto entered into the FMC early in the flight.<o:p></o:p>
<o:p></o:p>
PMDG 747<o:p></o:p>
<o:p></o:p>
Once the FMC is programmed and the path and profile computed, the MFC altitude window can be set to the cruise altitude. After T/D is achieved, each speed and altitude must be entered manually to match the FMC numbers for autopilot action ( ie NOT automatic as with CS). Staying on course is less better implemented than with CS, because frequent course deviations occur even at NORMAL simrates. ILS frequency is auto entered for the selected runway but later on in the flight near the approach. <o:p></o:p>

[fliger747]

I haven't flown the 757-767 but have flown the Smith's 737-400 and of course the 747-400 for many years.

I also worked with PMDG on the implimentation of their FMC. For the 747 the FMC works as with the real one with the exception the L-NAV tracking isn't as good as the real plane, due to some apparent limiations in FSX. The ILS does not auto tune the Correct ILS info till a good way through the flight, though it could be manually tuned. No reason to do this. If the speeds and altitudes are entered in the FMC legs page, the plane should follow the constraints presuming you have an end of descent point and have set the altitude window value to not stop the descent at an intermediate point, such as for an ATC limitation. When entering the airport area it is often much more convenient to use Flt Level Change and set the speeds manually. It will be of course necessary to set the speeds in the speed window as flaps are extended and and the approach is entered. The speeds entered on the legs page are mostly for prediction so the plane can calculate the path and energy backwards to the top of descent.

Cheers: T

[jimjones]

Thanks for the expert info.

Jim

[fsafranek]

I also noticed there are FMC included in the Flight1 ATR 72-500 and their Fokker 70/100 packages. Anyone have any experience with them? Good or to be avoided?
:ernae:

[fliger747]

Bernt Stolle who visits these pages and has a good reputation programming FDE's is a 757 pilot and might be able to comment on the veracity of the Cap'n Sim FMC. Programming by reverse engineering such complex software and making FSX do what it commands can be quite a challenge! That native FSX has pretty limited autopilot functions doesn't help!

Cheers: T