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clayton4115

landing below REF

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hi alli am practising manual landings in the 747 so i am manually calculating the speed / flaps and trying to stay on alignment,i have noticed that sometimes in my practises i am landing below the REF speed, i.e REF 143 and i actually put the throttles to idle 50' above and by the time the wheels touch the ground i am at 130kts, i do make a beautiful landing as the wheels just kiss the tarmac :( however i wanted to know whether in real life would this be a dangerous thing to do, i.e land below REF?here is one georgeous landing i just did!http://forums.avsim.net/user_files/186800.jpg

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Yes, you would have a lot of explaining to do, and eventually get fired if you were consistently Landing below VREF. you can add to vref but not subtract :)Rob


Rob Prest

 

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lol, well i seem to be getting some beautiful landings when my speed is a tad below REF.

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Hey Clayton, If it makes you happy then all good :) Real world a greaser is not necessarily a good Landing. This Aircraft needs to be planted firmly in most conditions and on target speed.Edit: Nice picture :)Rob


Rob Prest

 

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Hey Clayton, I may have misread your post. If your passing the runway threshold at VREF 30/25 then that is correct. Flaring the Aircraft and retarding thrust is obviously going to cause you to reduce speed just before touchdown. However flying the approach below vref would be dangerous.Rob


Rob Prest

 

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yes its at the very end where i am past the start of the runway where i RETARD and reduce all speed and make some nice landings!

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I would say that if you are maintaining VRef (+5 or even +10 depending on the xwind component), and then retarding throttle at the threshold, that is correct. There's a LOT of flat plate drag involved, so she bleeds of pretty quickly. That, coupled with the spoiler deployment will keep you planted.I agree with Rob- a greaser is not the goal- in fact, when the RA call progression is not spaced equally, and you get long pauses at 20 and 10- you use up LOTS of asphalt- very quickly.I like the 50, 40, 30, 20, tiny bit extra 10, and the spoilers deploying- any long pauses and on a balanced field you WILL be bumping up the autobrakes and using LOTS of reverse!Set up a flight with low RVRs in fog- no wind- fly at Vref and do a full auto-land and you will see perfect technique- not a greaser- but perfect!Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png


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Carl Avari-Cooper

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Carl,How low can you go? Flying the PMDG 738 VREF for flaps 40 with remaining fuel was 132 knots. In replay I noticed that I finally contacted the asphalt at exactly 120 knots after a bit of a float. It was not a greaser but it wasn't firm to the point where I felt that I had been shot down. The RA sounded very much as the call out you like. Is anything above a stall ok?Gerry

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Gerry:VRef is just that- the reference speed you should NOT be under- until the throttle cut/flare. In flight testing they determine average distances involved during the throttle reduction and flare and this variable is included in the landing/runway performance tables. You will note that most performance figures stipulate a new aircraft, good asphalt, tire and brake conditions and correct technique- with a disclaimer in case you do not meet all the conditions!Most rw pilots add a few kts for various reasons. VRef + 5 seems fairly common- unless in calm conditions. I am NOT typed in the 746, and you would benefit much more from some of our rw 747 pilots than from my myopic viewpoint.......Steve, Alex, Robert et al.......please chime in!Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png


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Carl Avari-Cooper

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Fly her on the numbers, I normally add 5 kts to the VREF, but will increase this by a margin of up to 15kts should the WX conditions merit (gusty WX or the possibility of windshear).It is important to maintain the correct RWY picture in addition to the APP SPD, you should be aiming for 50' min over the threshold, if lower or higher you should consider a GA - (Approach charts will specify the TCH - Threshold Crossing Height).At 30' RA I adjust the pitch attitude by approx 2.5-3 degrees, moving my line of sight down the rwy towards the far end, simeltaneously & steadliy placing the thrust levers at idle.Maintain this pitch attitude in the flare & she will settle steadily but firmly onto the RWY, ensuring prompt spoiler deployment & application of autobrake.Greasers may be good for the ego but your company training captain will take a dim view, & if the conditions are limiting you may find yourself into the grass or approach lighting off the other end.This becomes more of a critical issue in crosswinds or on wet runways.Add to this the crossed controls as you lay off the upwind drift couteracting the into-wind-wing with aileron & you will soon realise how important good timing becomes.I still make a real pigs ear of this technique from time to time LOLEnjoy & stay safe.Kind RegardsSteve Bell


Steve Bell

 

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Clayton,This may be a silly observation, but I don't see any flaps deployed on your 747 in the screenshot.Kim


supporter.jpg

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Kim,its because this was in replay mode and for some reason the animated flaps dont show, i assure you i was flap 25 at the time.

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Thanks for all the tips everyone. Clayton the missing flaps in replay has happened to me too. I got around the problem by not raising them before the replay was engaged.Gerry

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I think that by definition you touch down below Vref; the important thing is to be at Vref+padding (usually at least 5 knots, more depending on stiff wind, etc.) before you pass the fence. At the fence or thereabouts--for me at about 40' AGL--I start going to idle thrust (smoothly, not shoving to idle) and at 30' AGL, I pitch up to 4 degrees or so for the TD. I used to aim for greasers but found that I used up a lot of runway, landing about 2500' down, and also risked a tailstrike, so I no longer aim for that. It's nice for one's own pride but not necessarily safe. The thing is to fly the Queen down to the concrete smoothly and definitively. Aiming to land like a cream puff is not the name of the game. Thus, if my vertical speed at touchdown is -150 to -200 fpm I am reasonably satisfied although -50 fpm is always a delight if that can be achieved safely. But flying the plane onto the ground is key.Another thing that can happen is that as you attempt to grease and bleed speed and raise pitch, you can reach a point where suddenly you lose lift and your VS rises sharply during the last 10-20 feet which then puts you down with a thump that bruises the plane, alarms the pax, and hurts your ego!Jonathan


Jonathan Sacks

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but Jonathan, i see all the time in videos the pilots doing lovely greasers, well they look like greasers anyways.

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