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Pushing the yoke during flare

Started by ahaka, Thu, 15 Nov 2018 08:22

ahaka

With the marvellous aerodynamics and flight characteristicis modeling of PSX, it is a joy to learn and try to perfect your hand flying techniques.

I have found that many times during the flare on landing, I do not only pull the yoke, but sometimes give it a little push as well to prevent floating and adjust for an optimal touchdown. Usually this results a good touchdown rate and landing. What I'm wondering though is if this would be considered bad practice in real life and another method would be preferred (i.e just learn to always flare the exact right amount)? In videos I do see pilots move the yoke back and forth a little bit, but it is hard to tell if they actually ever need to push it forward or just adjust the pull force.

To me it is easy to flare too much as moving the throttles to idle drops the nose and gives you an impression that it is going to be a hard landing. Be too conservative with the flare and you DO get that hard landing. :) Pull/push the yoke to adjust is my best bet.
Antti

Britjet

Hi Antii,

An interesting post and you have hit upon a technique that does exist. It can and is sometimes used on many airiness types to evade what would otherwise be a hard landing.
If a rate of descent is still too high after the initial flare, a further flare input can actually make the situation worse as you are effectively rotating the main gear into the ground. On the other hand a slight push can achieve a ballon effect which actually raises the main gear slightly, and can avert the crunch!
The result is that the aircraft lands with a rather "flat" attitude (usually still firm, but not as heavy as it wouid otherwise have been).
While not a good technique in itself, it can be used to rescue a situation.
On the 707 it was employed routinely (I was on the 707) and some of the Captains were very good at it. I never got he hang of it unfortunately - the 707 was tricky to land!
I find myself sometimes doing it on PSX, and as you say, it does work!
Peter.

cavaricooper

Old 727 Captains will remember this technique as fairly common with that particular airframe configuration (long fuselage, rearward mains and a T-Tail).

PSX never disappoints.

Best- C
Carl Avari-Cooper, KTPA

cagarini

#3
And probably why at a local gliding club the two gliders broken in purpoising accidents took place in flights conducted by seasoned airline captains :-)


It's almost taboo to use a push during the flare in a glider :-)  but I do see it being used frequently in airliner cockpit videos...


I mean... this sort of stuff :


https://www.youtube.com/watch?v=cX4oFDEKm94

ahaka

That must be what I've experienced, Peter. Just didn't think of it myself as I was more concerned I'm just doing it wrong. :) Funny thing is I often do it if it seems I'm gonna float and then I get a very good landing in the end. It seems it is indeed very different to fly a large airliner compared to smaller aircraft, where the flare as I understand is a simple pull on the stick/yoke.

The 747 feels tricky enough for me at times during the final moments before touchdown. I have either floated or slammed hard many times. When floating, the ac sometimes goes a little off the centerline, and trying to use the rudder to correct it is easy to over control. Another thing I found difficult to manage at first was how much thrust changes affect the pitch attitude.

I guess the 707 was far more difficult? I remember reading how the pilots who flew the first 747-100s praised how easy it is to land the 747. I'm assuming many of them were coming from 707 at the time.

Antti

RogerH

When I learnt to fly fixed-wing microlight, my instructor told me to think of the stick as being on a ratchet on landing - you can pull it back, but it can't go forward again from that point. When I converted to flexwing microlights, I was also give the same instruction - you can push the bar out, but don't let it come back. So adding pitch-up commands (stick back, bar forward) was taught to be added incrementally but never reversed.

Of course, when one inevitably over-controlled, the brave (and insane) soul trying to stop you from killing everyone, would often override and either arrest the pitch-up control or even add some pitch-down. But I guess that was just to return it to where it _should_ have been pre-overcontrol.

When i read the OP, I was gonna weigh-in with this advice, but glad now I waited to see what the real guys said, interesting - I'm gonna try it in PSX and see how I get on.

Jeroen D

Only PPL, but same for me. I was taught never to push the yoke forward once in the flare. Just hold off and let the plane settle on the runway. If you havent got enough runway left go around!

Of course, on a single engine propellor plane pushing the nose down close to the ground, other from ballooning effects also means you are getting your propellor closer to the tarmac!

Obviously, a Cessna/Diamond/Cirrus have a bit of a different landing characteristic from the big jets.  You actually stall the plane as you float just over the runway and let it settle.

Here is me landing a Cirrus at Catalina Island, California.

Listen for the stall warning just prior to touch down;

https://www.youtube.com/watch?v=HRjUASwNz0g&index=41&list=UUZ19EsnMzDuYO78WBdga-Nw


Hardy Heinlin

Then let me add the stall fanfare of my landing at Merritt Island :-)

https://youtu.be/ZZrMNd8uikE?t=21

cavaricooper

Carl Avari-Cooper, KTPA

skelsey

Interesting topic and I should start by saying that my RW experience is limited to small aeroplanes and gliders, which certainly land very differently to jet transports and particularly the B747 where the flare is very limited indeed (per FCTM, only about 2-3 degrees change in pitch, which is basically just barely enough to perceive that the pitch has increased at all).

That said, although I can see how the theory works, the idea of actually pushing forward in the flare on a routine basis strikes me as somewhat asking for trouble (ie nosewheel-first landing), 707 aside. Relaxing the backpressure, on the other hand, I can see no issue with and indeed one should keep flying the aeroplane throughout the flare and landing roll, as opposed to simply pulling back and hoping for the best!

My general advice as far as PSX is concerned would be to remember to flare first - then smoothly bring the thrust back to idle whilst making small adjustments to hold the pitch attitude, with the aim of reaching the idle stop just as the mains touch down. If you snap the thrust levers back to idle quickly, or do so before you have established the landing attitude, you will be in a very dynamic situation which makes overcontrolling much more likely.

Markus Vitzethum

#10
Also, a couple of paragraphs from Capt. Richard de Crespigny's book on QF32 come to my mind, in particular the chapter where he describes the landing and flare of that crippled A380 in Sinagpore.

Quote:

"The rapidly lifting nose during landing was creating another problem. [...] So, as the nose lifts, the landing gear at the other end of the 'see saw' is thrust downwards. [...] and there was only one thing to rescue the landing - a radical manoeuvre that has to be timed very carefully.

At a fraction of  a second before I sensed the landing gear crushing down onto the runway - I pushed the side-stick full forward. This is not a trained technique as the risks of damaging the aircraft generally outweigh the benefits of the manoeuvre. And it's not something I aim to do on any landing but it's a fix that works if timed accurately. As the nose lowered, the wheels behind the centre of gravity rose, and the aircraft's rate of descent reduced as the plane settled onto a pillow of air trapped between it and the tarmac.  [...]
The fast descent rate washed off. Nancy-Bird [the name of the damaged A380] cushioned onto the runway and we touched down at only two and half feet per second."


The key to understand this maneouver is discussed in the previous chapter of his book. You have to understand that the landing performance calculation first failed after entering all the failures, and then, after using a sensible selection of inoperative items, showed a stopping distance of 3900m on Singapore's 4000m runway. Adjusting the speed was not an option as flying 1 knot slow triggered the stall warning, and flying 1 knot fast resulted in a stopping distance longer than the runway length. So it was essential not to land long, e.g. keep the flare as short as possible.

The result of this manoeuver was

"I'd hit my aiming point, giving us the best chance of stopping short of the runway's southern boundary. The flight data recorder shows we only took five seconds from 50 feet to touchdown, a fast transition, but a smooth one with no 'float'. In fact, we touched down two seconds earlier than the Airbus test pilots I was trying to mimic, so this gave us additional ground distance to stop."


Markus

jtsjc1

Great book and even though he was flying an A380 it gave a lot of insight on flying a commercial airliner without automation.
Joe

United744

One reason people have problems controlling attitude is because they move the controls but don't allow for inertia, so they push more when the aircraft doesn't respond, resulting in over-control, then they pull back violently in response to the initial over-control, and well, you can see what happens (also called Pilot Induced Oscillation).

Magoo

Not so much a push, more like relaxing the back pressure!