"Sliding" on touchdown

[shumway76]

Experienced on a C172:

Wind was calm on approach.
On touchdown at centerline, aircraft started to drift to the right (possibly wind from the left).
Corrected by left rudder (which also includes nose wheel steering).
Aircraft nose pointed to the left, but aircraft continues to drift to the right, and left main gear & left wing started to lift!
Corrected with left roll on the ailerons, but by this time approaching very close to the side of the runway, so selected full power & lifted off again since I still had sufficient speed for a "touch & go".

What did I do wrong? Why did the aircraft continue to drift with the wind even after I pointed the nose into wind when on the ground?

[flyinkiwi]

Based solely on what you've said I would say possibly wind sheer of some kind?

[MOREOIL]

Did you land flat three wheels at once? If so you were probably still flying, little or no weight on the wheels. Try fully stalled arrival on the mains and it should go where you point it, raising the flap on touchdown will help as well.

[Johnm]

I suspect the aircraft was still close to flying speed in which case you needed *both * aileron and rudder input at the same time to correct drift and maintain centre line respectively. Pointing the aircraft into wind is only helpful for a crabbed cross wind approach.

By the time the left wing and gear were lifting you had already lost it and going around was absolutely the right response:D

[mary meagher]

You did the critical action absolutely right! its all going pear-shaped, GO AROUND! We glider pilots don't have that option, so we have a very bad habit when flying power to forget about that option, and don't practice it near enough.

On that day you state "wind was calm on approach." Which sounds very much to me like a thermal must have been lifting off at your critical moment. This can cause a surprising gust of wind from a completely random direction, on otherwise a flat calm day.

[mad_jock]

Had you taken all the power off?

Other than that sunny day thermal, ground effect and the C172's ability to fly at very low speeds even when in theory you shouldn't be able to.

[172driver]

First off - congrats to the absolutely correct decision to go around.

As to what happened: as has been said, possibly too fast (a 172 does fly at amazingly slow speeds), possibly the 'gust from nowhere', a thermal.

But consider for a moment your initial reaction:

You applied left rudder. Now what does that do? It aligns the wing closer to the wind, IOW the wing now produces more lift. Result: left wing and wheel lift the a/c tries to weathervane into the wind and the situation gets worse.

What you need to do is to use BOTH aileron and rudder. Aileron to 'slip' into the wind, rudder to align the nose.

HTH

[FlyingKiwi_73]

Had very similar issue after completing my 172 rating, the answer, i was still flying..

Came in fast-ish bit of a Xwind but nothing serious, Unfamiliar with the cockpit and was selecting flaps ready for go round, had my head in the cockpit for a second looked up and saw runway lights very close by!!!! Full power and go around still sideways.

All three wheels were in touch with tarmac but a higher than normal arrival speed plus side wind meant my dabs at the breaks and rudder control were not going to do much with it being light on the wheels

Scared the hell out of me, i stuck the next landing and went home... i know when to quit!

[Pace]

What is wrong with being a "bit " fast in strong winds, shear and turbulence? I would rather carry a bit extra speed than hanging in the air near the stall at the mercy of those winds.
It is technique which is wrong not the speed of the aircraft
An aircraft can land on the stall 1.1,2,3,4,5 Xs the stall speed but can the pilot???

Pace

[FlyingKiwi_73]

Hah Pace has hit the nail on the head... rubbish pilot :-)

The wind wasn't strong, xwind of about 9-10 knots, but i'd only had around 6 hours on 'high wings'' and only 80 hours on low wing pipers.

[Pilot DAR]

When in contact with the runway, do not depend upon the wheels of a C 172 (or many other types) to have any significant effect upon the directional control of the aircraft unless one or more of the three conditions exists:

The plane is moving at less than 35 knots,
The controls are being held all, or most of the way nose up, or,
The stall warning horn is sounding.

[tecman]

I'd largely support Pilot_DAR's summary. In this sort of situation you want to set yourself up so that you use the aerodymamic controls (wing down, rudder as required) to keep straight. Then, without forcing anything, minimize the amount of time between when you're flying and when you're not. Depending on the aircraft and the conditions, a bit of light braking can be useful to get the speed down to where the nosewheel can be safely lowered. When you're very slow and have all three wheels down, you'll feel the nosewheel steering being effective. With the C172 etc remember to use the correct aileron inputs while slowing and taxying.

You do learn to tailor things a bit. My current puddle-jumper is a Tecnam P2002 JF (low wing) It's extremely light in the nose and (being an early s/n) has no differential braking. In very strong crosswinds - particularly from the left where you can run out of right rudder - getting all 3 wheels safely planted asap is a good thing if you want to avoid weather-cocking after touchdown. I hasten to say again that you force nothing - just approach at the right speed and slow safely to the point where you can get good ground steering effectiveness.

[EDMJ]

Happened to me too early in my C172 career, and I agree with the other comments to the effect that the aircraft was still flying (i.e. you "landed" much too fast".

One of the most eye-opening experiences in a C172 was practising really slow flight (with an instructor) and full stalls (not just approach to stall until the horn starts sounding). It's amazing at how slow speeds this thing still flies, and it'll give you the confidence you may need to fly the approach at the correct speed (which may seem much too slow for your own liking).

[Pace]

EDMJ

Please explain to me what the stall speed has to do with landing other than minimizing the braking and stopping distance?
It is a misinterpretation to connect the two in such a way although I fully understand what you are saying.
If I am flying in strong winds, turbulence, shear and i have 20 /30 kts down the runway why would I want to be hanging around near the stall?
This is a technique thing not a stall speed thing

Obviously if you crab in offsetting the wind to maintain the centre line flair too high and purely kick the nose straight you will be in the hands of the wind and float off to the side of the runway as you would if you did not crab to offset the winds down the approach. Its not rocket science.

Pace

[EDMJ]

When I got converted to a C172, it was at an airfield with an 800m (later extended to a whopping 1200m) runway. The club instructor drill was to fly the approach with full flaps at 70 kts. This obviously often resulted in a lot of float, and the occasional urge to force the aircraft down (during one of which occasions I had the same experience as Shumway).

Then I had long hiatus from C172 flying and when I took it up again, it was from an airfield with a 400m runway. The drill with this operator was to fly the approach at 60 kts.

This seemed inordinately slow to me, based on my previous experience.

The aforementioned exercise showed me the full envelope of the C172's performance and proved very visibly that flying the approach at 60 kts is perfectly safe, with (more than) the required margin (1.3 x Vs) about the stall speed. After that experience I never let the speed creep up on approach more or less subconsciously on approach anymore.

In the weather conditions you mention I would of course consider adding a bit. However, in my neck of the woods we seldom have more than 10-20 kts down the runway, and on the really good flying days, no or very little wind at all. On the latter occasions, maintaining the appropriate approach speed is imperative for a nice landing on our short runway.

In other words, minimizing braking and stopping distance is usually rather important to me. I don't consider a long float neither elegant nor safe either.

[Pace]

Hi

I realise I am being pedantic and know the normal is 1.3 x flap set above the stall.

The most accurate is to use an AOA gauge :ok:

But flying too fast and floating is still a technique error as you can fly literally onto the ground with minimal flare.

There are conditions where the last thing you want is to be holding off at the mercy of the winds and any shear or up currents.

In that situation putting it down is far preferable.
holding off to land near the stall is one way but not the only way to land!
As long as your aircraft is not short coupled mains to nose you could theoretically land at cruise speed! If on landing at cruise speed you shoot 50 feet into the air sorry its still technique which is wrong not landing the aircraft at high speed!

As stated in a similar thread a friend of mine with control problems landed a Citation at 200 kts intact at Edinburgh way over the tire speeds and ref speeds of 105 kts ( Mad Jock was there when it happened and am sure will verify)

So if you float off the runway it's technique you need to get right not so much speed.

If you ever get to fly faster and heavier machines the last thing you want is to be holding off to get a smile on the MDs face with a perfect touchdown only to sail off the end of the runway with a smile turning to a look of horror :E

Pace

[Dak Man]

Sounds like understeer to me.