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Guest JTH

Why wouldn't my plane descend?

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Guest JTH

Using FS Build v2.2, I built a flightplan from EINN to EGLL (flight time of about 50 mins in a 744) and exported it as an MS Flight Planner file and a PMDG FMC file.Anyways, I loaded the plane in Flight Planner, entered "EINNEGLL" into co-route on the FMC and it seemed to load the route okay. I took off, engaged the A/P and it followed all the waypoints and took me to the right destination as it should. But the problem was that it never descended when I was approaching my destination and I was still at my cruise altitude of FL270 when I was over the airport.I set the altitude dial to 0 well in advance to "allow" the 744 FMC to descend at the correct time, so that's not the problem. I did notice that the last waypoint on the ND was reading as "RWY29R", which I assume is Runway 29R at Heathrow. FS Build must have entered this as I did not - in fact the clearance Heathrow tower gave me was for Runway 9, but I didn't enter that in the FMC as I didn't think it was necessary. Maybe that's the cause of the problem? I'm not sure. I've already gone into the approach page of the FMC and programmed a flap setting of 25.Any help on this would be much appreciated. Thanks a lot, JTH.

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Guest morvious

Are you shure you had VNAV engaged?Sometimes I notice just before t/d that VNAV disengaged, so I had Speed and Alt Hold on.Also, if you reset your MCP alt to late, and you already crossed the t/d, the plane fails to descend, because it will go to Alt Hold and Speed.When you enter an airport, you need to set the correct runway for arrival into your fmc. It wil dial your ILS frequenties automaticly.Cheers,---------------Stefan van Hierden>|

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Guest JTH

Thanks a lot for the reply.How do you know where the T/D (top of descent) is? I've wondered that for a while. Also, seeing as setting the MCP too late is a problem, would you recommend setting it very early in the flight - like once I reach cruise altitude?And finally, do you mean I should set the approach runway in the FMC before I takeoff or when I'm in the air? The problem is that I don't know what runway I'll be landing at until that airport's tower tells me, and I'm pretty close at that stage.Thanks once again and let me know... JTH :)

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Guest D17S

TOD is shown a couple of places. On your ND. It will show up as a little green dot with TD by it. Also, fly with your FMC up. Glance at your Legs page. Look at the right side of the page. Those are the altitudes Vnav is programmed for you. Look for the first waypoint altitude that starts a descent from your cruise altitude. Your TOD is right in there somewhere. Zoom out the ND if you're within 320 miles of it. Look for the dot. But keep the FMC on the Vnav Cruise page. When you are within 50 miles from TOD the LSKs at 2-3R will start a count down. Get closer and the FMC will put a message in the scratch pad telling you to reset your MCP altitude window. That

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Guest JTH

Okay, thanks again for the replies.I repeated the flight twice today with mixed results. Firstly, I now understand the T/D and I set the MCP to 0 when I get a message on my FMC telling me to do so. But I couldn't see how to choose on the FMC which runway at EGLL to land at. I pressed the INIT REF button, then went to the approach page. At the start of the flight in the runway field it just said PARK, ILS or something, but when the flight went on a bit I noticed that it had changed to Runway 27R, and gave the ILS frequency for it. But I did not see anyway to change it to say runway 9R for example. Could you help with this?Anyways, I figured I would leave it for now and just land at Runway 27R. Everything seemed to be going smoothly, and the plane seemed to be descending correctly and was now approaching the last waypoint (RWY 27R). But then I noticed that the plane seemed to have "misjudged" the distance as we were now under 2,000 feet and still a good bit away from the runway. Eventually, my 747 crashed into the ground at about 10 miles from "RWY 27R". I did not have the runway in sight (maybe I was too low) but I did see lots of planes in the vicinity, so I reckon I wasn't far off. Do you have any idea why the plane would have come down too early like that?The second flight was even worse! I thought I followed the same procedures exactly, but this time at the T/D the plane didn't descend at all (in fact it's altitude was very jumpy overall, at one stage it went above my cruise and at another stage it fell below my cruise). My VNAV was on but I figured it mustn't have been working properly. I did get an FMC message that said "CHECK ALT TGT" but I have no idea what that means. Maybe you could help?Thanks once again to everyone for their help. Hopefully I will complete this flight successfully tomorrow!

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Guest D17S

When you are initially programming your FMC, set your origin and destination on the ROUTE page. After you do this, just have a peek at the legs page. There

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JTH-Please note that we REQUIRE users to sign their posts in this forum. Failure to do so can lead to deletion of your thread.Okay- couple of thigns.... You have GOT to spend some time in the manual reading. :-)This is a tremendously complex airplane- and it will bite you if you don't spend a bit of time learning how it is supposed to be flown. It sounds to me from reading this thread that you have discovered that the airplane will never depart from altitude without your intervention. ATC would have a "cow" if you just departed your assigned altitude because the FMC told you to. ;-)The DES NOW function is available for instances where ATC tells you "Descend Pilot's Discretion to XX,XXX." It allows you to have the airplane gently enter the descent phase without waking up the folks in back.If ATC doesn't tell you that you can depart your cruise altitude- you are supposed to stay where you are.... A good pilot will recognize that he's approaching Top of Descent and call ATC to ask for lower.Okay- now- the second problem you report: Crashing into the ground short of the airport....Did you really set the altitude selector to sea level and tell the airplane to descend there? Oh boy. :-)I'd spend a bit of time learning to program sid/stars and use vnav to assist you. VNAV will allow the airplane to use a normal, stablized descent- including a required distance range for level off and slowdown....If the airplane flew into the ground- it is because you instructed it to. Remember that about this airplane...it's only as smart as the guy driving!


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Guest JTH

Sam and everyone else, thanks for taking the time for writing out such detailed replies. Unforunately I am still unable to fly this route successfully. Here's exactly what I do:- I build the route EINN-EGLL with FS Build v2.2.- I start up the plane as normal, open the FMC and enter "EINNEGLL" into the co-route. I then enter the runway I want to start from, make up a flight number, activate the route and press the executive key. In the LEGS page, the FMC now reads all my waypoints, and the last one reads "RWY27R", even though I never selected a runway. If I try to change this to another ILS runway in the "DEP APP" page, the LEGS page gives me the "route discontinuity" error. So I stick with Runway 27R.- I enter 11,000 ft into the MCP, which is the initial climb altitude given to me by ATC, and arm LNAV and VNAV. I flick the Flight Director switch and arm the autothrottle. I then take off as normal, press the left A/P command button, and the A/P climbs to 11,000 ft. Once there, I immediately change the MCP to my cruise altitude of 27,000 ft and press the MCP knob so the A/P climbs to my cruise.- At this point, I enable time compression and speed up the simulation. The plane reaches cruise, and follows all the waypoints as normal. When I approach the top of descent, I set the simulation rate to normal and twist the MCP to 3,000 ft to allow the plane descend on schedule. It does, and as I pass the second last waypoint and start heading the last 30 miles to the final "RWY 27R" waypoint, I enter the flaps 25 landing speed that the FMC gave me + 5 knots into the A/P, and the plane begins to slow down. I arm speedbrakes and autobrakes, lower the flaps on schedule, lower the gear etc.- At this point (approx 25-30 miles from the "RWY 27R" waypoint), I press the LOC and APP buttons in the hope that A/P will then commence the autolanding but it never works. I don't know if they should both be on, both only the APP button lights up. I also sometimes get FMC errors when I do this. The plane doesn't go below 3000 ft when the MCP is set at 3000, and the time today I tried setting the MCP to 0, the plane landed at the airport alright - but not on a runway! In fact it touched down a few hundred feet to the right of one of the runways and crashed into a building. But other times I have tried this landing the plane just hasn't landed at all.I feel I must be doing something wrong, and I've given step by step detail of everything I am doing in the hope that someone can see where I am going wrong. Thanks once again for all your time and patience!

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