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JSACKS

Problem with ILS with default 747

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I am just learning how to land ILS, and I am having trouble with the default planes. The ATC tells me to descend to 2000 until established on localizer (I have already setup NAV 1 and NAV 2). The plane then picks up the glide slope, turns and descends to the runway. However, at about 1800 feet the plane suddently enters a steep dive, and never makes it to the runway! I don't know what is happening. And yes I am using APR mode on the AP.Here I am flying a 747 from KOAK to KSFO (a nice short flight), just to test it out. Here are what my settings are:http://forums.avsim.com/user_files/15138.jpgOn final:http://forums.avsim.com/user_files/15141.jpgThis is where the AP brings me! :http://forums.avsim.com/user_files/15143.jpg2 more seconds after that I am in the San Francisco Bay.Please help me!!

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first offFS2002 Loc / App is totally different to 2000, i strongly suggest you learn on the default 737 how to capture and intercept the localiser, you need to be no greater than 190ias for intercept and flap 10 BEFORE the GS hits the middle diamond, the plane will dip for abit, but keep reduce speed and keep applying flaps till full flaps and speed 140 ias, i had the exact same problem till i did the above, now all my landings are spot on!there is a tutorial someone else posted here, do a search for it.regards

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Looks OK but your speed is a bit high on approach. A successful ILS approach in the default 747 requires:Flaps 25 by 1500 AGL, to be stable a tad earlyIAS of around 155 by then, possibly as low as 150 (or 145 to 148 with flaps 30)Max fuel of 40,000 lbs.Steady eye on AP behavior to ensure it doesn't overtrim and send you into nose dive. I find that "nursing" the trim even with the AP on works well.I know KSFO like the back of my hand in real life and in FS too, and the ILS works very well there.Hope this helps. Post again!JS

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These are all good suggestions--it's crucial to be stabilized early and in fact I like to be more or less at Vapp (usually around 145-148 with flaps 25 for me) by the outer marker. That might be a bit sooner than the pros do it, but the pros have better equipment than we do. If you set up in good time and with the proper speed, it should coast down the glideslope perfectly--all you have to do is cut the autopilot as you cross the threshold, retard the throttle to idle, flare, and it should settle right down onto the runway.However, the absolute most important thing to be checking here is fuel load. I've seen variants of this question pop up hundreds of times, with all different aircraft, and 99% of the time the problem is caused by trying to land with way too much fuel on board. Even 40,000 pounds is pushing it; I like to come in with no more than 10-15,000 pounds, and that's why my approach speed is lower than that of other posters. How much fuel you load depends on where you're flying, but unless it's a 12-hour flight or more, you shouldn't be loading anywhere near full fuel. Too many pilots just leave it at 100% fuel to start since that's the default--you can get away with that in a Learjet or a Cessna, but if you try to do it in an airliner, you won't be able to hold the glideslope unless you're shooting the approach at 200 knots, which would just cause a gear collapse when you hit the runway anyway. For the same reason--less stress on the gear, the brakes, and the aircraft in general--you want the lightest load and the slowest approach speed that's safely possible. Check your fuel load before turning to final, and if you've got more than about 15,000 pounds I'd strongly suggest using Alt->Aircraft->Fuel to "dump" some.EDIT: Just noticed you mentioned KOAK to KSFO--I'd load about 30,000 pounds for that flight, no more. If you left it at the default full tanks, that means you're trying to land with about 90% fuel left--so, no surprise you're crashing.If you're serious about flying the 747 well I strongly suggest buying the PSS package, which you can now get for about $15 online, and pairing its panel with the POSKY or Meljet 747 model. The PSS panel will help you figure out the ideal fuel load, approach speed, flap setting, etc. for your situation. There's a bit of a learning curve but it's well worth it.Hope this helps.Regards,Marc SykesSenior Vice President, Los Angeles OperationsPacific West Airwayswww.pacificwestairways.com

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Thanks a lot everyone! I really appreciate the help. I'll try your suggestions and report on any progress.Thanks again,-Raj

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Mark:Just to pick on one point you mention: fuel load. Yes, indeed, many a simmer has tried to land the 744 unsuccessfully with 350,000 lbs of JP1 aboard!But actually, the standard fuel for landing many a 747-400 is 25,000 to 30,000 lbs. It's under 10% of max fuel so very manageable even if the ZFW is maxed out at 535,000 lbs. My wife's former airline, a famous Asian airline with a good record, was severely caned by the BAA a couple of years ago for landing their 744s at Heathrow with only 4 to 5 tonnes of fuel; the minimum for a 744 at EGLL, I believe, is 8 tonnes. One of the senior captains of the airline told me that 4 tonnes is ample, because you know things way in advance during descent, but in fact I disagree totally. It provides a small margin for go-arounds, surprises, holding, and bad weather diversion.The venerable Captain Tarmack usually recommended practising approaches in a normally laden 744 with 30K to 40K lbs of fuel and if you think about it, it makes sense. The Queen uses an average of 24,000 lbs per hour and if you take account of circling/stacking, flying to an alternate airport, etc., then such a weight of fuel is not exceptional.Sorry to pick on it but I know and love the Queen like no other big iron and I can't resist leaping in like this !Cheers!JS

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