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Speed question

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I posted this in the other (proper) forum, but got no love on it, so I figured I'd ask here...I've been flying FS for quite a few years now, from back in the Sublogic days, but I've always had trouble with speed, specifically, going too fast. I always find myself either struggling to slow down when I'm practically right on top of the airport, or stalling somewhere along the way.My main question, and what might help me a lot, is this:In an airliner, being at 10,000 feet 30 miles out is approximately the target, right? Well, what should my speed be then? 250, or less, and by how much? What other speed targets should I be shooting for along the descent?

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Here's some love for ya (IANAP, but):1) FAA rules stipulate 250 knots or less below 10,000 feet ... so right there is your starting target.2) Take a look at the flap extension speed limits for the aircraft you are flying (click on Aircraft / Kneeboard / Reference). That will give you a good approximation of what you should be doing in preparing your aircraft for landing. Since you need full flaps on landing ... and you cannot have full flaps until your speed is at a certain speed ... presto! There's a big, fat hint.Flap extension limits for the default 737 start at 250 kts for 1 degree of flap, and reduce down to 162 knots for 40 degrees of flap. Right there is a hint. You shouldn't fly this aircraft faster than 162 knots with full flaps or you risk damage to the aircraft. Vref approach speeds in the 737 with gear down indicate 165 knots at 80,000 pounds gross weight. So, there's your minimum speed target on landing.3) Have you looked up the approach plate for your favorite airport? Approach plates will many times provide you with guidance on speed and altitude when approaching the ILS system for a given airport. You can usually find approach plates for major airports free on the internet. They will state preferred speed and altitude limits when you capture the ILS.4) Here's a good starting point for KBOS:http://www.fltplan.com/AirportInformation/BOS.htmHalf the fun (to me) of using Flight Simulator is that it gives me a chance to flex my troubleshooting and problem solving skills. I too wondered how to slow down, until I figured out that the reason why I was going too fast is because I wasn't planning properly.There's a saying in aviation: Stay a few minutes ahead of the aircraft. Makes a lot of sense when you're going 200 miles an hour!Happy Landings,Kevin

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Heres what I use for a general guideline for jets. This is just general but easy to remember. I plan to be at these numbers at those altitudes, so you have to begin slowing well before you reach them.(If you are using live ATC they will sometimes give you speeds to ensure separation from other a/c.)30 milesAlt 10kSpeed: 250 kts20 MilesAlt 8kSpeed: 200 kts15 milesAlt 5kSpeed: 15010 milesAlt begin descent to published GS intercept altSpeed: slow to approach speed per manual for the plane5 milesGS intercept altSpeed: approach speed (usually 120 to 150 depending on the aircraft)

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Here's a routine that works well for me and I believe is in line with RW practices. This for a 737.30 NM out = 10,000' MSL @ 250 KIAS22 NM out or on base leg = 6,500' AGL @ 220 KIAS14 - 18 NM out or turning onto final = on (or below) GS @ 180 KIASOuter marker = on localized on glide slope start reducing speedTreshold = Vref + 5 Knots (about 140 KIAS)R-

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Pretty much what everyone else has said but more general...We usually use our 3 times table for this (eternal) problem of energy management.Very roughly on a three degree slope it's :10nm = 3000ft20nm = 6000ftetc.So at FL360 you'll need about 120nm to descend. For a calculation of top of descent that works quite well.As you get lower and are being vectored about, don't forget to add a few miles to slow down, on the Airbus we usually leave about 10nm from 320kts IAS to green dot (usually around 200ish).Each aircraft flies a bit different so you need to get used to your favourite, you may find it slows down more or less than that.While in the US they like their 250kts below 10,000ft, most of the rest of the world doesn't give a monkeys and will happily let you keep high speed to any altitude, traffic permitting. This can help if you're a bit high, indeed only this morning I was at 310kts, 6000ft going into Oslo.Using this system works just fine in the sim but in the real world the big problem is you often don't know exactly how many miles you have to touchdown. Guessing that is half the game.Of course once you start getting really close to the airport <20nm you can start using flap and/or gear to add drag to rescue a high and fast approach (or indeed when ATC cut your track miles right down). The gear is usually pretty good at killing off energy, even if it is a bit inelegant. Again, you'll need to get to know your aircraft and it's limits/performance. On the Airbus, 180kts and Flap 2 gives you a good rate of descent (1,000 - 1,500 ft/min) and is useful for capturing the glideslope from above if required. From there, gear down about 2,000ft aal (fully established) and flaps out about 10kts below the limit speed should find you nicely stable by 1,000ft aal in all but the strongest tailwinds.Hope this helps, or at least gives you somewhere to start,Ian

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I don't have the sim in front of me, but where do I find VRef?

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Usually in the manual that came with the plane. You can also check the 'kneepad'.

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"While in the US they like their 250kts below 10,000ft, most of the rest of the world doesn't give a monkeys ..."Ian: I'm pretty certain that this is for reasons of air traffic control. If you were to look at a map of airplanes currently flying in the United States, and compare that with some countries in Europe (excepting Heathrow, of course), you'd see what I'm driving at.For example ... here's current US traffic at 5:00 in the afternoon:http://forums.avsim.net/user_files/179745.jpg

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Alright, yeah, I found the VRef speed easily enough. I've been flying the pattern in the default 737 at KDTW just to try it out and it's working quite well. Also, thanks to a YouTube video that showed the autoland procedure for the PMDG, I've got a better idea of what exactly I should be doing on approach.Now I'll have to set up a 10,000-feet situation that I can practice from. Thanks for all the help!

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