Re: Slipped off left again

[gsamsonite]

Are you serious??????






That is absolutely ridiculous. Are you really a Qantas pilot?

[Wingo]

No, not a Qantas pilot. I'm a cadet, which means they are training me how to fly from the start. At the moment I'm flying little C172s and around 70 hours of experience. So guess what, I still make a few mistakes. So does everyone who is learning to fly. I can proudly say mistakes do happen, but I learn from them. This is probably one of my worse, which in perspective isn't all that bad. If you had flown an aircraft, you may understand just how hard it is.

[Brett_Henderson]

There are many things that will happen to you behind the yoke, that will leave you a wiser, better pilot. Some during training, but most, obviously, well after training. I admire that you're willing to share them... most aren't.

It sounds like there was a significant cross-wind during that takeoff ?

If so, then a "launch" into ground-effect, with an immediate crab-angle, was the best way to handle it. But not as reaction. That's something you'd plan on doing. It sounds here, that it was a reaction on your part.

If crosswind was not a factor, I'd need more information before commenting further.

No matter what happened... the bottom line is that you kept your head about you, and piloted your way through it. If you had enough airspeed for for lift (which you obvioulsy did), then aborting the takeoff with significant yaw could have been much worse.

It might have been a poor choice to continue with a takeoff that started with yaw problems from the first application of power... but it was good piloting on your part to get out of there in one piece.

Again.. I need more information..

[beaky]

:-?

Wind? takeoff from dead stop, or on the roll...?

This problem is just plain mysterious  without more info... unless you inadvertently start the roll with the nosewheel cocked to the left or there is a big-BIG! left crosswind, a 172 should not charge to the left like you describe, even if you're late with the right foot to compensate for prop/engine effects. That's been my experience, anyway, with near 200 hrs in type.

But I also agree with BH that "flying out of it" is always the wise course, rather than becoming resigned to a trip into the weeds.

But for heaven's sake, be sure to seek more advice from the instructor(s) you are flying with... ultimately, the instructor is responsible, indirectly, for the progress of the student. Your training issues belong equally to the instructor.
If that isn't part of Qantas' cadet program, it should be.

And one more thing:  never assume the tires will help much, friction-wise, in this situation.
They're not really made for that. Don't wait until it's obvious they will not help keep you straight.

[Brett_Henderson]

Rotty's right... even 180hp C172s have pretty negligible torque/p-factor to deal with. Any x-wind at all presents more of a directional problem during a takeoff roll. And the odd thing is that it sounds like you were dealing with a x-wind from the right, not the left.

If you've ever flown and older C172 and then hopped into a newer model (or one with new rudder/nose-wheel hardware), the difference is dramatic. I've flow C172s that had so much slop betwen the pedals and the nose-wheel, that differential braking was required while taxing. And on newer models, the ground steering was was very precise with pedals alone. Maybe after taxiing onto the runway, you had a sloppy nose-wheel, already cocked to the left. And if you were already aimed slightly to the left, the addition on torque/p-factor added to the mix would have you applying LOTS of right pedal.

The other point of Rotty's that is most important; is your instructors evaluation. He knows you, and he's ultimately responsible for your training. It's hard for us to "instruct" by forum post.. so before incorporating ANYthing we say.. please run it by him. I've seen two very seasoned and competent instructors get into heated debates about how to handle their students.

With that said... I'm thinking that the scenario I mentioned, might be what happened... and you probably over corrected. I'm just having trouble understanding how you got into a drifting situation like this. You say that the nose was point right, but the plane was drifting left.. and it sounds like it started happeneing very early...as in, right from the begining of the takeoff roll. I know things happen quickly when we're caught off guard in the cockpit..so maybe the loss of traction happened further into the roll than we're understanding... Although, If you were alone (and from one of your photos, you look rather "small" (as in WELL under 200lb), and if you were flying on tanks under 1/2 full.. a C172 will get up to "lauch" speed in a hurry.

Anyway..a wind from the right would call for LEFT pedal at first. Right pedal would just compound the wind-induced directional problem. Then, as lift began to negate the tires, you'd have to decide when to launch into ground-effect, because drifting would set in. That can be a scary and critical time for a new pilot. Eventually, you won't give this stuff too much thought. You'll be instinctively flying the airplane as you roll out onto the runway.. and your feet will do their stuff on reflex. You won't think, "OK, first I'm countering the torque, then I'll deal with the wind".. it will all just happen. Every takeoff is a different dance with the pedals..

[Wingo]

I was doing a solo nav and had flown about 70 minutes and done a full stop landing to stretch my legs. I had done a fuel check before take off and it was at around 165 litres, or 118kg, or around 260 pounds. Aircraft BEW is 797kg and I'm around 65kg, total weight would have been 975kg or around 2145 pounds.

The take off was done from a full stop in light winds, the windsock was limper than a 90 year old. There were no flaps extended and the initial roll under low power was straight. I always ensure that I am running straight before applying full power.

When full power was applied the nose pulled left due to slipstream, I think being more likely than torque. Its not a sudden or powerful pull, but it is noticeable and is usually easily corrected with some right rudder. When the nose swung left this time I did the usual of correcting right, admittedly it was a bit late but I have corrected from worse. I applied the right rudder, it wasn't a hard correction. The nose moved right so it was straight with the runway and the aircraft continued left, I guess due to inertia. I heard the tyres scraping the runway and it reminded me of what happened last time. Rather than abort and run off the runway like last time I lifted early into ground effect before climbing.

I was watching the ASI during the role, following the SOPs. This all happened in the range of 35-45 knots.

EDIT: Now that I think back, when I lifted I barely stayed in ground effect, the aircraft seemed to have enough speed/lift to climb out and accelerate to best angle speed. It accelerated quite quickly was I was off the ground.

[Brett_Henderson]

I'd just chalk it up to one of those learning experiences. To this day, things happen to me for the first time. Sometimes I fully understand what happened; sometimes not.

I think you have a good enough understanding of it all to remember the important stuff.. and the poise to work through it when it happens. Most important is that you're humble enough to want to talk about it.

Eventually, the rudder dance will be second nature.. even with nasty x-winds  :)

[Wingo]

The only conclusion I can draw is, like last time, the aircraft was light enough to start to lift before my usual rotation speed. I did talk to my instructor about it, but like last time he was stumped.

I'll just keep in mind that this may happen again, and try to work out the reasons behind it. So far the only constants are I was solo, in the exact same aircraft (VH-KHE), and a reduced fuel level.

[Brett_Henderson]

Yeah, and don't forget the intangibles.. especially in a lightly-loaded airplane.

It might very well have been calm, but when the difference between the wheels having traction, and not having traction might be 38 as opposed to 41kias..that three knot window can be erased by the slightest of wind gusts.

One thing to think about.. maybe.. would be to change your take-off trim a tad.. when it's just you and not much fuel..

Just thinking out loud.

[Splinter562]

Could you have been dragging the left break?

Edit:
A tricycle gear aircraft (with the mains behind the C.G.) is stable on the ground. The aircraft's nose should try to align with the direction of motion rather than go away from it.

[Mobius]

I'd agree with checking the brakes.  Ask whoever works on the aircraft if the left brake looks and functions as it should, also ask about the wheel bearings or anything else that might do that.  If you ever see anything on the preflight, or have any questions about anything like that, never, ever hesitate to ask whoever is around, and if nobody is around, don't go.  It's not worth getting killed over.

I have almost 200 hours in 172s and I've never had an issue like this, so I  would imagine it would be an aircraft issue (no offense, I'm not trying to say I'm better than you, just that in my opinion, it's probably an aircraft issue).  I've never noticed that slipstream has never had so pronounced an effect as to pull the nose to the left enough to do what happened to you.  I don't really know what else it could be.

One other thing, when you fly, where are your feet on the rudder pedals?

[Wingo]

One thing to think about.. maybe.. would be to change your take-off trim a tad.. when it's just you and not much fuel..

So trim it down more to apply pressure to the gears?

A tricycle gear aircraft (with the mains behind the C.G.) is stable on the ground. The aircraft's nose should try to align with the direction of motion rather than go away from it.

As I understand it would, when the tyres have reasonable traction. The drift seems to occur due to inertia acting on the entire aircraft and the tyres losing traction when I correct.

I'd agree with checking the brakes.  Ask whoever works on the aircraft if the left brake looks and functions as it should, also ask about the wheel bearings or anything else that might do that.  If you ever see anything on the preflight, or have any questions about anything like that, never, ever hesitate to ask whoever is around, and if nobody is around, don't go.  It's not worth getting killed over.

I will ask about it, but I don't think so. All of our 172SPs behave in the same way. The yaw left is noticeable when power is applied during takeoff, requiring right rudder to correct. Don't quote me, but I think they have the most powerful engine of any 172 which may explain why it does this.

I have almost 200 hours in 172s and I've never had an issue like this, so I  would imagine it would be an aircraft issue (no offense, I'm not trying to say I'm better than you, just that in my opinion, it's probably an aircraft issue).  I've never noticed that slipstream has never had so pronounced an effect as to pull the nose to the left enough to do what happened to you.  I don't really know what else it could be.

No offence taken! I understand you have more hours in this type than me, and welcome any input or ideas.

One other thing, when you fly, where are your feet on the rudder pedals?

As low as possible! During my first few hours I made the mistake of leaving my feet on the brakes. Lukily the instructor took control quickly and fixed up the aircrft. As I said, I have made some mistakes but I always learn from them.

[Mobius]

Hmmm, it's all very odd.  I've flown the 180 hp 172 quite a bit as well, so I don't know why they would be any different.  As far as trimming goes.  I usually try to trim to the so the aircraft will rotate and fly hands-off a little above typical rotation speed (~60 kts, Vx, but check the POH or PIM for your speeds).  There should be a mark on the trim indicator that marks where the trim should be at take-off.  Other than that, I would just recommend making sure you are on the centerline for the entire take-off roll and if you start to deviate at all, correct it immediately and get flying as soon as possible.

How about this - do you notice a substantial left yaw once you're flying?

[Wingo]

I always make sure I'm lined up and going straight before applying full power.

There is a mark on the trim for take off position and I trim to it before taking off.

On climb, and any time full power is on, a fair bit of right rudder is needed to correct for the left yaw induced by the slipstream.

[RitterKreuz]

is it possible that your heels were not on the floor and you touched the left brake pedal?