Why push forward on the control column on landing?

[cheeky monkey]

Hi there,

I've recently started flying a 737 and have flown with a couple of Captains who think that the control column should be pushed forward during the landing roll after the nosewheel has made contact with the ground.

Does anyone else do this or know why?

Other Captains I've flown with say it's unecessary............

Your thoughts please.

Cheers

[WOK]

All Boeings I've flown (4,5&6 NOT 3) require only very light forward pressure if any once nosewheel down, except in the case of a low-level coupled approach when the AP has applied aft trim b4 touchdown.

If you stuff the stick forward too much you just run an increased risk of nosewheel shimmy if the torque links are a bit slack.

If one was struggling with steering control it might help, but I don't think it is necessary or even desirable under normal circumstances.

FWIW the only (large commercial) machine I've flown which positively does require fwd pressure after touchdown is a certain fast & pointy bird, currently without a CofA for no good reason. http://www.pprune.org/ubb/NonCGI/frown.gif

[exeng]

Dear Cheeky Monkey,

I quote from my companys Flying manual ('Landing Techniques' from the 'Normal Procedures') which states:
"Nosewheel steering will be improved with a forward pressure on the control column which increases weight on nose gear."

This is the technique I was taught and I apply it at all times.

WOK states, <If one was struggling with steering control it might help, but I don't think it is necessary or even desirable under normal circumstances.> I agree with WOK to a point, in that I don't believe it is always necessary. However I believe it is better to routinely apply light forward pressure on all landings rather than waiting until the day that you are struggling with steering control.

WOK also states, <If you stuff the stick forward too much you just run an increased risk of nosewheel shimmy if the torque links are a bit slack.> I'm not sure about this point, however shimmy is always a possibility if the torque links are slack. By the way I never 'stuff' the nose forward but apply light forward pressure in a controlled manner. (When I'm having a good day that is!)

Hope this is of help to you.


Regards
Exeng

[CaptainSquelch]

Monkey,

During flight the chances of hitting an object are rather small. Now from the moment I touch these chances are increasing dramatically and seriously hitting an object tends to decreases the length of the aircraft. Then I still need the column to touch the nosewheel, but as soon as that is done I like the column as far away from my n~ts as possible. I don't like the front row of the choir.

[dusk2dawn]

Boeing 727 Flight Crew Training Manual page 04.35.04 / 05

"Landing Roll Procedures"
Upon touchdown, immediately but gently, lower the nose wheel onto the runway,
<...zapped...>
The pilot not flying should hold forward pressure on the control column after the nose wheel touches down in order to assist in nose wheel steering effectiveness.

[Check-in]

Different strokes, different folks, or is it the other way around? If the thrust reversers are at the tail,and set fairly high eg DC9, 727 and a few bizjets, as reverse kicks in, the nose will want to pitch up, so forward pressure is needed.
737 and similar shouldn't need much, if any, forward pressure under normal conditions, a bit maybe to load the nose in a crosswind. Then there's the dear, lovely BAE 146 which fares better with a bit of back pressure AFTER the nose is on AND spoilers up, because you need to put weight on the mains to stop it wheelbarrowing or lifting one side in a crosswind. Like all things, moderation is the go.

[sprucegoose]

All good suggestions and I've used them all at different times...especially the 146! Bloody airplane. I would suggest that at any time during the initial rollout after landing with the speed still fairly high that forward pressure should be light. Remember the nose wheel is not designed to take all that weight. I saw a pilot push full forward on the yoke of an A300 one morning after touchdown. Nose dipped down on the oleo quite a bit. That was a lot of weight on the front wheel and it won't like that treatment forever. 146 on the other hand abuses its nose wheel on landing with little input from the pilot. Bloody airplane.

[Centaurus]

As far as I am aware there is no documented requirement to hold the wheel forward after touch-down in the B737. The ground spoilers have already done the job of putting the weight on the wheels.

However, I have noticed that in the 737 simulator, pilots that have come from prop aircraft to fly the 737 for the first time, almost universally apply forward stick after touch-down and during reverse thrust. I believe that they have brought this habit from previous aircraft which are not spoiler equipped and in which forward stick puts more weight on wheels for better braking.

Similarly I often hear ex prop pilots replying to the B737 80 knots call by the PNF on take-off, as "I have control" instead of just the basic acknowledgement word of "Check". This also probably stems from the transfer from nosewheel steering to rudder control around 80 knots in some turbo-prop types.

[Air Conditioned]

Fighter pilots used to say that forward stick produced an upwards tail force reducing wheel loading, and therefore if enough brake was applied to keep the nose down then aft stick would increase brake capability. ('specially when the antiskid operates.)

Maybe. I have always thought it particularly ugly to use lots of forward column when there is no call for it. Every pilot seems to instinctively know when enough is enough.

[cheeky monkey]

Thanks for your comments guy's, I appreciate the feedback.

I think I'll apply light forward pressure from now on as I can see no real reason to push the stick fully forward.

Everything in moderation!

Cheers

[DOC.400]

Thankyou 4 this thread!
I was intrigued that both Iberia pilots did this in a 737-400 at LGW.
Positively forced it down!!

[Propellerhead]

What affect does speed-brake deployment and reverse thrust have on pitching moment - are they nose up or down?
If they're nose up, then forward pressure would help prevent a tail strike on landing (especially if you get slow on the final approach).

I know this is diverging slightly as you are all talking about pressure once the nose is on the floor, but I would be interestsed to know.

I know that the accident reports on the numerous A321 tail strikes (Midland and Air 2K) sighted nose up pitching moment as the auto-speedbrake deployed as a contributing factor. Is a tail strike on a 737 less likely? I would guess so.

[QAVION]

"I think I'll apply light forward pressure from now on as I can see no real reason to push the stick fully forward."

Hi, Cheeky.
The 747-400 autopilot gives a 2 degrees nose down command during Rollout. Perhaps your engineers can give you the equivalent value on a 737.... this might be a rough guide as to what to do.

Rgds.
Q.

[sprucegoose]

B727 definately has a nose up pitching moment with the spoilers deployed. You will need to "check" forward on the control column. I've actually tickled the tail skid on one landing when the nose attitude got a bit high in the flare due to a sudden decrease in headwind ie high sink rate developed. I mistakingly eased the nose up and when the speed breaks deployed I scraped the skid just a smidgen. Got lots of phone calls from the cabin crew down the back! You live and learn.

[FuelFlow]

cheeky monkey

This is from the Boeing 737 pilots training manual, page 4.48, October 1997

"Fly the nosewheel to the runway smoothly by relaxing aft control pressure. Do not attempt to hold the nosewheel off the runway. Holding the nose up after touchdown for aerodynamic braking is not an effective braking technique."

"To avoid the risk of tailstrike, do not allow the pitch attitude to increase after touchdown. However, applying excesive nose down on the elevator during landing can result in substantial forward fuselage damage. Do not use full down elevator."

Taking this into consideration, I would suggest a gentle forward pressure on touchdown. As QAVION suggests, a 2 degress nose down command should do the job correctly.

With regards to takeoff the Boeing book states the following,
"Light forward pressure is held on the control column"

Bearing this in mind I would say the the same amount of forward pressure be used for T/O and LDG.

All the best.
FF