Scary Moment

[Donalk]

Managed to scare the bejaysus out of myself this week and am a little confused about what went wrong. Had about 12 knots crosswind component on a wet runway, and used a combination of crab on final with a transition to wing down at about 300 ft. Touched on the upwind main first then got all the rubber on so thus far everything was proceeding according to plan.

As detailed by my instructor during numerous practise sessions I continued to hold into wind aileron during the landing roll, ie continue flying the aircraft, but when I touched the brakes the aircraft started to weathercock quite dramatically. Suffice to say that a good approach and landing was somewhat marred by my snaking down the runway. At one point I thought the wingtip would strike but happily I managed to escape with nothing more than severely bruised pride and sweaty palms.

Later on it was explained to me that holding into wind aileron reduced the lift on the into wind wing thus creating more friction force on the upwind tyre. Consequently this had the effect of encouraging a weathercocking action. This is at variance with what I have been doing all along so am I missing something.

Would appreciate any advice from more experienced pilots

[Pilot DAR]

Donalk,

I wouldn't sweat it too much, it sounds like everything other than the use of brake was just as it should have been. You'll remember for a long time how it felt to have a very exiting landing, and what you're going to concentrate more on next time to make it less exciting. Depending upon your aircraft type, and available runway, consider using much less or no brake, and more runway. It will be longer, but neater! (pretend you're having to pay for the brakes) It sounds like you continued to fly the plane after you contacted the runway, and that's great! Keep that up.

Perhaps one disadvantage (I don't know the circumstances of your flight) is that this was the last landing of that day's flying. It was not good, and you could not "get right back on the horse". I occasionally have landings I did not like, and I always go and do another circuit, so my last landing satisified me. THus the really bad one is not fresh in my mind! I accept that if someone's waiting for the plane, this may not be possible.

This will fade into your collective experience, and become a part of what makes you a better pilot. Don't analize it too much. Once you understand how to do better next time, concentrate on that. Eventually landings will become second nature, then you'll only scare yourself a few times a year. You'll never stop scaring yourself completely!

Pilot DAR

[SkyCamMK]

You mention wing down but not opposite rudder? Have you considered aquaplaning or was it not wet enough? There could be various contributory factors - get some practice with an instructor in similar conditions if you can afford it otherwise stay calm and wait for some more comments. Good luck

[Donalk]

Yes forgot to mention opposite rudder. This is the procedure I have practised with my instructor several times. Runway was damp but little or no standing water. I think Pilot Dar might have something in that I could have been a little enthusiastic on the brakes in an effort to make the first exit.

The controller had asked for an expedite if possible and I was probably too keen to comply.

[Jucky]

I agree with Pilot DAR, sounds like you did everything OK until you hit the brakes. You might have inadvertently put more pressure one brake and this is easily done if you are tense and in difficult flying conditions. When you realised you were weather cocking you may have then over compensated on the other brake and from here it can be easy to get into a braking induced PIO. If this happens just release pressure on both brakes and re-apply both smoothly and evenly.

The other possibility is aquaplaning. It can take as little as 1-2mm of surface water to allow aquaplaning to occur. If full aquaplaning occurs the tyres can actually spin down and come to a stop and that's without using the brakes! In full aquaplaning the surface water is fully supporting the weight of the tyre and can make directional control of the aircraft difficult to say the least. To work out the aquaplaning speed for your aircraft you can use the following formula; V=8.6√P (lbs/in²) or V=33√P (bar)

where V=full aquaplaning speed in knots and P=tyre pressure in units indicated.

When landing on a wet runway, make a firm touchdown and apply light continuous braking when the aircraft is firmly on the runway and the wheels have had time to spin up. Retardation on a wet runway will be considerably reduced therefore you will require more runway than normal. Use the entire runway if necessary. If you think the aircraft isn't slowing down rapidly enough and you are running out of runway, go around and have another go.

[Mark1234]

Even if not aquaplaning, it's perfectly possible that with reduced grip on a wet runway you may have locked a wheel or two - at which point directional control becomes a bit iffy. Think the rest's been covered.

[Molesworth 1]

braking induced PIO


What is PIO?

[Gertrude the Wombat]

The controller had asked for an expedite if possible and I was probably too keen to comply.
Ah! - I was going to say "I only use the brakes when ATC ask me to expedite [as they did on my last landing]" until I got to that additional information!

I don't have to (pretend you're having to pay for the brakes)because the club keep reminding us that we are paying for the brakes in the hire charge.

[tmmorris]

PIO = Pilot-induced oscillation (due to overcontrolling and a lag between moving the controls and them taking effect, can lead to an oscillation becoming worse. The classic case is the landing bounce which gets worse and worse until the nosewheel drops off, but snaking on the runway can be just as bad.)

Tim

[VFE]

Crosswind landings explained simply:

Allow the aircraft to crab down the approach using power as per normal and maintaining perspective using the ailerons.

At point of flare, close throttle, use rudder to point nose down runway and apply opposite aileron to counteract yaw and hold off until she sits on the upwind wheel first.

What's so difficult?

VFE.

[Jucky]

The controller had asked for an expedite if possible and I was probably too keen to comply.

Why do so many PPLs allow ATC to dictate to them? :ugh: Remember it is the Aircraft Commander's responsibility for safe conduct of the flight. The controller is not sat in the aircraft and therefore can't see the same information the pilot does. I know most of us try to be helpful to other aircraft and ATC (I know I do where I can) but there are occasions like this one where it is not always safe to do so. So what if the aircraft behind you has to go around? That's his/ATCs problem for getting too close to you in the pattern. It's better than him not being able to land at all because you have skidded out of control and crashed on the runway! A friend of my mine once had his undercarriage collapse as he expedited a turn off the runway at ATC's behest! It was however his fault for not telling the controller "NEGATIVE I'll take the next turn"! Don't let that be you!

[VFE]

"NEGATIVE I'll take the next turn"!

Even quicker than that just say "standby" to any requests.

VFE.

[Jucky]

Good point!

[Deeday]

"Unable to comply" is the correct phraseology in a situation like that one - that's my understanding.

[S-Works]

I had a similar experience recently going into Coventry. After an ILS in a 20kt crosswind with cloud at 500ft overcast DZ and a very wet runway I went sliding down the runway aquaplaning. I put it down to trying to keep the speed up for the traffic behind me and being used to flying my work airplane so much recently which is several tonnes heavier.

The day we stop learning is the day we stop flying!!

[VFE]

I had a similar experience recently going into Coventry. After an ILS in a 20kt crosswind with cloud at 500ft overcast DZ and a very wet runway I went sliding down the runway aquaplaning.

You sure there wasn't a thunderstorm, engine fire, and sick passenger on board too Bose? Man of your calyber 'n' all... :rolleyes:

VFE.

[S-Works]

We had another fall out recently VFE or you just being a prick for the sake of it?

[Donalk]

Point taken - blustery day, wet runway, crosswind and one of MOL's 738's up my ass = pressure. Add an ATC expedite instruction and the low hours start to show. On your collective advice I have just added 'unable to comply' to my aviation vocabulary.

[Gertrude the Wombat]

On your collective advice I have just added 'unable to comply' to my aviation vocabulary.
That's the correct wording, but of course "communicate" comes last, so you only say anything at all when you've got the capacity.

[Molesworth 1]

At point of flare, close throttle, use rudder to point nose down runway and apply opposite aileron to counteract yaw and hold off until she sits on the upwind wheel first.

Be ready to take your foot off the rudder as soon as you touch down (should the a/c suddenly decide to veer in a different direction) or apply differential brake or you'll end up on the grass like I did recently!

[RatherBeFlying]

If there's a good crosswind, there's usually a headwind that helps slow down the a/c once on the runway.

I don't recall the last time I used braking until down to a running speed in a crosswind landing.

Plus adding braking when still busy with into wind aileron and rudder can destabilise things as you have found out.

Perhaps a touch on the downwind brake would work, but in a taildragger I'll be staying off the brakes until time to turn off unless necessary for directional control.

[vanHorck]

PilotDar explained it very well.

Such a problem gets compounded on a wet GRASS runway where a sideways skid can happen easily. If it does, release the brakes immediately and correct with gentle rudder. Only re-apply brakes when directional control is regained.

My technique is to dump ALL the flapas soon as all 3 wheels are on the ground, before gentle braking is applied, to take away any remaining lift and use the full weight of the plane to keep the beast on Terra Ferma.

Braking is obviously safer at lower speed than higher speed, so decide where you start to break deciding on the length of the runway.

Braking should commence very gently and only when you feel you retain control should you increase the braking action.

This is just my opinion