You can fly the approach faster with no flaps to somewhat reduce the crosswind impact (provided the runway is long enough). Simply put, the higher the airspeed the lower the crab angle, but for an approach I would not go all mathematical about it.
Just flying the approach faster is going to be counterproductive, floating for ages in crosswind is not recommended…
My current plane has large flaps and CS prop, plus fairly high wing loading that in combination requires a fair amount of throttle opening to maintain even a fairly steep approach angle. When the throttle is closed it slows quickly. That’s not so good if the engine were to quit on final, but very useful in allowing as much as 1.4 or 1.5 Vso on final if deemed appropriate, 75 or 80 kts. Since a crosswind typically moderates close to the ground, and because the plane can be slowed without trouble, you can slow on short final and it seems to work out pretty well even without transitioning to a slip. You can just straighten the nose with rudder before touchdown. This is in stark contrast to my previous Luscombe on which I didn’t crab at all, crossing the controls and slipping all the way down final at 55 or 60 kts, using the ample rudder authority to do so. Touchdown in a crab is a very bad thing in an unstable and sensitive tailwheel plane, and even with a 20 kt crosswind it had enough rudder to slip if you were adept enough to use it. Planes can be quite different.
It’s useful in practice for calculating whether or not you should plan to land at an airfield or not.
Crosswinds which I would accept for a DA42 I possibly wouldn’t in a DA40. And I would accept a much higher crosswind in a DR400 than I would in a PA28. That’s in the planning.
IMO pilots really need to practice and master crosswind take offs and landings.
If you can’t hold the centre line keep practicing or lower your acceptable crosswind limits.
I also feel ga pilots should try both side slip and crab. There is a reason why CAT crabs rather than side slips.
gallois wrote:
It’s useful in practice for calculating whether or not you should plan to land at an airfield or not.
I don’t understand that. The ability of an aircraft to handle crosswind depends not only on the speed on final but also on the amount of rudder authority and possible design issues such as how much you can bank on touchdown without putting a wingtip on the ground.
To give two concrete example. The Cessna 150 and the Evektor Sportstar have very similar final approach speeds with full flaps (52 vs. 53 KIAS). Yet the first one has 12 kt demonstrated crosswind while the other one has 18.
The Cessna 172S has a final approach speed of 61 knots with full flaps and 70 knots with no flaps. (A 14% difference.) Yet in the first case the demonstrated crosswind is 15 kt, while in the second case it is 20 kt. (A 33% difference.)
How does the “effective crosswind” concept help you in these cases?
I take the TÀF at destination as part of my planning. I know the aircraft I am flying. I know what my speed on final is. So I know what to expect the effective wind to be.
From that I can decide whether it’s a go ot no go.
My briefing.for landing will include whether or not I will use full flaps or just one stage. On many aircraft this would be take off flaps or I could go no flaps.
I do not use the wing down side slip method. Experience with different aircraft has brought me to favour crabbing down final keeping the nose on the centre line. I flare.at my normal height and as I round out I bring aircraft straight down the runway with rudder whilst at the same point adding some into wind aileron (based on feeling for the strength of the wind). I touch down as II normally would and if necessary apply a little more aileron as necessary to keep me on the centre line. Very rarely would I have to add extra rudder to remain on the centre line as I slow..
I don’t know what else I can tell you. It’s a method which has worked for me in every aircraft I have flown. I have also used it to land in crosswinds higher than those demonstrated even after the Ve calculation. But that is of course only on occasion when there was little or no choice as the insurers do not take into account the word “:demonstrated” and treat it as a limit set in stone.🙂
It was the method I was taught and a method I use quite regularly and get plenty of practice..The wind does not always blow straight down the runway on Isle d’Yeu and Ouessant and fronts coming in from.the Bay of Biscay can have winds changing quickly in both direction.and speed here at LFFK.
But that is of course only on occasion when there was little or no choice as the insurers do not take into account the word “:demonstrated” and treat it as a limit set in stone.
Do you a concrete example of this? There is no POH limitation on crosswind capability that applies to any plane I’ve flown, and I’ve never heard of the manufacturer demonstrated capability that is published for some planes being held up as a limit by an insurance company,
To claim that the demonstrated crossword capability is a limit is tantamount to saying if you land in a crosswind exceeding that number you are breaking a regulation. That is in actuality untrue, and the demonstrated capability is intended by the manufacturer to be a sales tool, not a limit. I think the insurance company would therefore have to explicitly state this in the policy contract to make it apply.
gallois wrote:
So I know what to expect the effective wind to be. From that I can decide whether it’s a go ot no go.
So you treat all aircraft as equal in the relationship of max crosswind to speed on final? What the POH says about crosswind doesn’t enter into the planning? That seems very strange to me. Where does the effective crosswind limit come from?
I don’t know what else I can tell you.
You could tell me how you would handle my two examples in practice.
I´ve flown the Caravan in excess of 500+ hours, though 10+ years ago. This airplane handles like many aircraft heavier than that one. In X-windy situations, you´d fly a crap type approach with flaps 1 step short of full (higher roll/aileron authority), add some extra knots on approach, considering steady mean head wind and gusts, and then de-crap just prior to touch down. 95% of commercially certified jets are flown the same way, when you have the choice.
I do the same – crab all the way and just prior to touchdown wing into wind and opposite rudder.
Same here.
