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andreadebiase

What's the correct way to land smoothly?

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Ok, here is what i do and would love to hear your landing technique. Let me anticipate that i do have the tendency to float leading to a smooth touchdown but a bit too far compare to what i would like to see.

Anyway my two questions are: 

-As soon as the runway threshold disappears under my nose I disengage A/T and cut off thrust completely. I this ok? i think i have read others keep the thrust until the tires touch the runway and i think at that point thrust automatically is cut off (??).

-When do you start flaring?

 

 

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Ok, here is what i do and would love to hear your landing technique. Let me anticipate that i do have the tendency to float leading to a smooth touchdown but a bit too far compare to what i would like to see.

Anyway my two questions are: 

-As soon as the runway threshold disappears under my nose I disengage A/T and cut off thrust completely. I this ok? i think i have read others keep the thrust until the tires touch the runway and i think at that point thrust automatically is cut off (??).

-When do you start flaring?

Watch how the autoland does it then copy.  I start to decrease thrust at 50 ft and usually have pulled it back to idle by 30 ft but you have to watch your speed. I like to be right on Vref+5 over the lights and if conditions are calm I'll allow speed to decay to Vref over the numbers. Too much speed and you will float.  During the final moments before flare, my focus is on the touchdown zone but I shift my focus the the other end of the runway when I start to flare. It makes it easier to gauge the final few feet of descent by watching the full length of runway.  Generally, you are not trying to make the smoothest landing possible, the safest landing in windy conditions is a solid leave-no-doubt landing. The two key factors are speed and practice.

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A good reference to learn how to correctly land the NG is the FCTM manual page 6.10 (provided with the NGX) and onward. The landing technique is pretty well explained.

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the safest landing in windy conditions is a solid leave-no-doubt landing.
But not so solid that it results in a bounced landing. Emirates just found that out the hard way...

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Dan gave great advice. Watch carefuly the autoland, power reduction and flare.

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Short answer, stabilized approach to 20 feet.  Raise the nose slightly at the 20' RA call out.  Reduce power to idle at the 10' call out.  A bit simplified but it will get you in the ballpark.

 

Make some landings using the HUD and pay attention to what the flare cue is telling you.

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If its landing technique you want to here here's mine

 

Autoflight - captured glide slope where I'm at flaps 10 on speed. Lower gear drop flaps 15, drop speed bug down to VREF (30). Get the plane configured to land (checklist).

 

Once checklist complete, pull up the HUD. Turn off A/T and control the speed yourself on the way in, dropping flaps at the proper times. Once stabilized on the speed (and flaps are down to 30) click off the AP totally. Fly it in manually following guidance from the HUD (that 30 degree line in the HUD should be worked right to where you want to touchdown). I always figure the approach can be rough as you need, jerkey wheel movements... up and down on the stick as hard as you need to in order to ensure you are in the exact place you want to be as you're flying over the apron. Then smoothly cut the throttle as  you go over the apron...

and the (this is important) start trimming the nose up... the reason for this is I've found cutting the throttle wants to pitch the nose down, and if you cut the throttle without trimming, it will nose over and your reaction will be to pull up too hard, and the result is an altitude gain and a vicious circle of pulling up and down trying to touchdown.

If you do that trimming it will balance out and only a very slight pullback on the stick is necessary. Smooth touchdown reverse thrust till 80 knots, cut engines and you're on your way. 

The trimming is key and you won't pick up on it on the autoland, cause the only cue to trimming is the trim noise you hear... but that noise doesn't always sync up with the actual movements. But if you autoland, take a listen right before the flare you'll hear it trimming. 

Also helpful for me to have altitude callouts. You'll get a feel for what the proper timing is for callouts and know whether you're good or not.

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I never have a problem landing the 737NGX. Whilst I do not fly the plane "by the book" (I prefer "low and slow" cross country VFR sight seeing tours, and control the final approach entirely with throttle adjustments), it is extremely stable and predictable on the glide slope, and I usually cut the throttle and start to flare at around 50 feet. It has more than enough momentum to maintain good pitch stability until touchdown. I have all of the altitude callouts enabled (more because I enjoy hearing them than anything else), and I engage the thrust reversers and spoilers down to around 70 knots, followed by application of the brakes (manual) when the thrust reversers are disengaged. I do this because the plane stops way too quickly when brakes and thrust reversers are used at the same time, and I just prefer a slightly longer rollout.

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From what I've heard, the landing is one of the areas where the NGX differs a bit from the real aeroplane -- 50R is very early to start the flare. The real NG pilots I've heard from generally are of the view that if you close the thrust levers at 50R in the real thing you will drop out of the sky very (gear struts through the wings) quickly, whereas the NGX sounds much floatier.

 

Nick is quite correct that reducing thrust will result in a nose-down pitching moment. Boeing's advice is to smoothly retard the thrust levers to be at the idle stop by main gear touchdown, and that's what I generally did with the PMDG 747 and LDS 767 -- a smooth, gradual reduction in thrust from about 30R, albeit with the rate slightly modified on occasion to take circumstances in to account (bit quick over the threshold? Come off the power a bit quicker. Bit slow and/or low? Bring the thrust back a bit later/slower). Naturally you will need commensurate backpressure to resist the nose-down pitching moment and raise the nose slightly. The change in attitude in the flare itself is only around two degrees, judged visually (i.e. not by looking at the ADI) -- by the time you start the flare you need to be looking down at the last third/end of the runway to allow you to judge the attitude change and the rate of descent.

Two degrees is just barely enough to be perceptible: i.e. hold the nose where it is with backpressure as you close the thrust levers, then just enough extra backpressure so that you can just sense that the pitch attitude has increased. Then hold that new pitch and wait for the touchdown!

 

Two common errors:

  • Shying away from the landing in the last 200 feet or so when it starts feeling as through the ground is rushing up to meet you, and on top of that ground effect starts to take hold -- keep it coming down on the glidepath!
  • 'Ducking under' in the last 100 feet or so to flatten out the flare and touchdown -- you can imagine the obvious potential problems with this!

The important thing is to focus on arriving over the threshold at the right speed, the right height and on the centreline. If you can do this consistently then you are putting yourself in to a good position for the flare. If you are always arriving over the threshold at different heights/off speed etc then you will never get a consistent 'picture' from which to learn to recognise the cues for the flare, and so you will struggle. As we can't (yet, in the NGX at least!) fly with an instructor who can demonstrate the correct technique and 'picture' for you, the advice to observe the autoland is good. I would also suggest that you freeze the sim at various points -- say 100ft, 50ft, 20ft and 10ft -- and take a good look at the 'picture' out of the window -- what does the nose attitude look like? What's happening to the speed and the thrust? Perhaps even take some screenshots at these points so you can go back and look again later, and really get that image of the horizon/runway environment etc relative to the nose at each stage of the landing fixed in your mind.

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From what I've heard, the landing is one of the areas where the NGX differs a bit from the real aeroplane -- 50R is very early to start the flare. The real NG pilots I've heard from generally are of the view that if you close the thrust levers at 50R in the real thing you will drop out of the sky very (gear struts through the wings) quickly, whereas the NGX sounds much floatier.

 

You might, emphasis on might, be able to get away with going to idle at 50' RA if you are landing flaps 15.  Do that with flaps 30 and you will have a rather uncomfortable arrival.  Do it with flaps 40 and the airport operations people will need to come and pick up the pieces of the airplane you left behind on the runway.

 

With flaps 30 I usually idle the power at the 10' RA call out.  With flaps 40 I carry the power a little longer and go to idle as I touch down.  Each landing is a little different and you may need to carry thrust a little longer or shorter to suit your conditions for that particular landing.

 

In any case idle thrust at 50 feet is a bad, bad idea.

 

As for the flare, I usually start it at the 20' call.  Again, you might do it a little earlier or later depending on the landing, but certainly not at 50 feet.

 

Pay attention to the cadence of the RA call outs.  After a while you get the feel of how fast the calls should come.  If they are coming to rapidly you have a higher sink and need to flare earlier.  If you are high and floating the calls come slower.

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I have just completed a landing at EGJJ Jersey, and I flared at 30 feet (not 50 as I had recalled earlier). Remarkably stable and elegant aircraft when landing.

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