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B738 - Flaps 40 vs Flaps 30 technique

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B738 - Flaps 40 vs Flaps 30 technique

Old 6th Sep 2015, 21:31
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Does anyone know how long a flare is in perfect conditions?
What I mean by that is, if you have a ROD of 750 fpm at 50ft while doing 150kts across the ground, and then conduct a perfect flare at 25ft, how many meters is it from 50 ft to touch down. The ROD obviously decreases as does the ground speed but only by a few knots. If my aim point is exactly 1000ft, and I conduct the perfect flare ( let's assume constant ground speed for simplicity of 150kts), where will I touch down? I would hazard a guess at about 1150ft, maybe 1200ft.
Interesting discussion. I find that by looking out the window I automatically vary the timing of my thrust reduction according to the rate of change I see out the window. Once in a while I find it necessary to keep thrust in until late in the piece, most of the time it is similar to a flap 30 landing.
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Old 7th Sep 2015, 13:33
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Slamming the thrust levers closed does nothing.

How long does N1 take to reduce.....
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Old 7th Sep 2015, 14:12
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Real men slam the throttles, or advance them, faster than the engines can respond.

It's especially entertaining on the application of takeoff thrust if one engine doesn't accelerate. One engine lagging the command thrust sector? Push the throttle farther forward?!?! That explains the skid marks you see when holding in position. They start on the centerline and have a nice curve towards the side of the runway before skidding back towards the centerline.
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Old 7th Sep 2015, 14:31
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Originally Posted by misd-agin
Real men slam the throttles, or advance them, faster than the engines can respond.
I have somewhat of an annoying habit of slamming them into full reverse. I think it started during OE when just popping them into idle reverse proved trickier than expected. So, I learned to rip them all the way back, then adjust.
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Old 7th Sep 2015, 18:36
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Most commonly I see pilots leaving the thrust in longer then slamming the levers closed. The only thing it leads to is a float as the N1 reduces at the same rate as if they had followed the manufacturers landing technique (you know the people that built and certified the aircraft).

Then again, people do what they want despite what Boeing recommend and our instructors teach.
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Old 7th Sep 2015, 19:18
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Do we really need to discuss how to flare F30 vs F40? Can we not just assume that everyone here knows how to do it? Every landing is different; weight, wind, gusts, thermals..
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Old 7th Sep 2015, 19:32
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Real men slam the throttles, or advance them, faster than the engines can respond.
Especially from full reverse directly to forward idle, followed by heavy braking when the aicraft begins to accelerate on landing roll
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Old 7th Sep 2015, 19:52
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172: finally, a modicum of common sense. Every time is different. It is not a manoeuvre that can be fitted into the modern day trained monkey philosophy. Thank gawd there is still a moment that can still can be an assessment of competence & understanding. It is a moment, on any aircraft, that a certain finesse & dexterity is required. You either have it or you don't. Perhaps you can learn it, but those who want to do it by numbers ain't gonna get it.
Every a/c is different, every day/runway is different. You have to adjust and cope & control the beast.
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Old 7th Sep 2015, 19:57
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As a last resort, if you can't accept or don't receive ADEQUATE INSTRUCTION, neither from your company's training captains nor from their approved SOPs, try watching the autoland doing it, make a note of what it does and go imitate the "box".

It's quite humbling to see how well Mr Boeings autoland performs, even to a time-expired old geezer like me!
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Old 7th Sep 2015, 20:26
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I would get a bit twitchy if the f/o began raising the nose at 50ft like the auto pilot does. Maybe tell your mate before you try to emulate that one
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Old 7th Sep 2015, 22:00
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Of course every landing is different. Talk about stating the obvious! The thing is, you need a reference point to start from when learning a maneuver & this is what most here believed the original poster was seeking.
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Old 7th Sep 2015, 23:32
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Of course every landing is different. But they're not night and day different. Everyone agrees that no flaps are a lot different than F30 or F40 landings. Why? Speed, sink rate, and drag.


F30's ARE different than F40 landings. Like the difference between no flap and F30/F40 landings? No, of course not. But a F40 landing is not the same as a F30 landing.


Does it take some sort of crazy type of techniques, like guys used to say the 727 needed? Of course not. But an awareness that you're using a lot more thrust, so the plane will be quicker to slow and generate an increased sink rate if pitch control is less than ideal, might be worth telling a newbie.
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Old 8th Sep 2015, 08:21
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Some landings my ass tells me to start pulling at 50 ft and leave the thrust in until I feel the rate of descent has been broken, even until touch down. Other days when the LW is 48 tonnes and that 10 kts TW magically disappears at 100 ft I merely give it a nudge at 10 ft.

The FCTM works well in the perfect world (and in the sim), but otherwise it's a seat of the pants maneuver.

With that said, I trust you all here to be able to land a 737 whether you are book type or not.
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Old 8th Sep 2015, 09:25
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You are right about the 727 mdg, loads of bs techniques on that aircraft.


It could be landed quite normally with a normal flare and idle thrust despite adamant opinions that could not be done.


I saw more long landings on that aircraft than any other type as Pilots were just terrified to take the power off.
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Old 10th Sep 2015, 04:22
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Let us be careful here, loco`s will turn the technique into a SOP.
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