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Air is a strange and wonderful thing. It supports us on our magic carpet ride, but also tries to push us where we don’t want to go. There’s been an evolution in my attitude about the challenges of the invisible hand.
Though wind is reported using such simple numbers like 270@15G20, I’ve come to believe that 20 knots here is not always the same as 20 knots there. Subjective factors such as terrain, turbulence, and gust direction are as important as the numbers.
I live near Boulder, Colorado. The canyons just to our west focus the wind and cause huge wind variations over short times and distances. Multiple times I’ve launched into calm conditions and returned in high winds, sometimes diverting to a nearby airport where it’s still calm. The prevailing wind at Boulder Airport (KBDU) is easterly, while at Rocky Mountain Metro Airport (KBJC) only nine miles away, it is westerly. I’m no meteorologist, so I can only explain it with one word– microclimate.
I did a checkride in 30 knot winds in the flatlands of Kansas, almost straight down the runway. It felt like pushing it for that airplane, but checkrides are so hard to schedule I went. In a 172, near vertical takeoffs and landings are fun! The hardest thing was taxiing, since you definitely can flip or hit the prop if you use the wrong controls and/or hit the brakes at the wrong time and let the wind get under you. Here’s a video of a 182 flipping in 30 knot winds at Las Vegas (with jet blast the deciding factor).
I’ve landed in strong winds enough times that 30 knots can seem routine, as long as it’s reasonably aligned with the runway. In the Great Plains, the Texas panhandle, or Wyoming, almost every day is 30 knots so you’d better get used to it! Then came the landing in 20 knots in the Hill Country of Texas, west of Austin. Those little hills made for fiendish turbulence down low. The lower I got, the worse it became. I’m stubborn and I kept thinking it’s just 20 knots, and I’m a CFI (beating chest). Until I was porpoising down the runway like a first-time student. I went around the pattern a few times but finally got a clue and decided to go elsewhere. Hmm, maybe even 20 knots isn’t always routine.
Later on, I flew an Angel Flight from Denver to Rock Springs, Wyoming in a Mooney M20J. The rule around the mountain west is do your summer flying early, because of thunderstorms almost every afternoon. But the patient was hours late, and I found myself returning late in the afternoon. It was fun doing over 200 knots groundspeed over Rawlings until I realized a solid wall of thunderstorms had formed between me and home, and there were 35 knot winds below. What to do?
I could turn tail, but things were not much better back further west. In hindsight, I should have stayed in Rock Springs, but too late for that now. I have flown Mooneys a lot and a low wing helps. So I decided to try the approach, and see how it felt. A low approach couldn’t break anything. The landing turned out routine, and I waited out the thunderstorms and made it home that night. Hmm…sometimes 35 knots is easier than 20?
Several times I’ve landed smoothly in a strong crosswind, then had trouble keeping the airplane on the runway. I approach using the wing low method. As soon as all three wheels are on the runway, only the wheels are counteracting the side force from the wind. In those first few moments after touchdown, not much weight is on the wheels so there’s not much side force. You get a skipping motion, sideways toward the downwind runway edge. I’ve never gone off, knock on wood (my own head). The flying is not always the hard part.
I approach using the wing low method in a crosswind.
In a left crosswind you need right rudder during your sideslip, then once on the ground you need left rudder to correct for the skipping and keep the aircraft centered. I finally learned to time the change of rudder direction better, straight as the nose wheel touches the ground, then as needed to stay upwind. When possible I like to land diagonal on a wide runway, which takes away some of the crosswind and reduces skipping.
Which brings up a point about gusty crosswinds. Gusts are not always in the same direction as the reported wind. Gust direction is only reported if it varies from the steady wind by 60 degrees. Some say that in the northern hemisphere gusts are from a direction further clockwise than the steady wind, but that is debated by meteorologists. More likely it’s random. The gust direction can make a crosswind worse, or better. A 45-degree crosswind from the right plus a 20-degree gust that is even further right, makes for a tough rollout. Since gust direction is so unpredictable, this worries me when conditions are difficult.
Gusts also lead to an element of luck, which can affect your judgment. Just because you landed once or twice in some tiny airplane in a crazy wind, does not mean you could succeed every time. The critical part of the landing may have occurred during a lull, so maybe you just got lucky. How do you know? We take pride in landing in tough conditions, but maybe all it really says is we used poor judgment in trying!
Here in Colorado most pilots know that flying over the mountains is a serious undertaking. The rule of thumb is 25 knots at ridge top level is the maximum, otherwise turbulence and downdrafts will be hazardous. Many a pilot has come to grief in supposedly high-performance aircraft by not respecting the reduced climb performance. Hmm…sometimes 25 knots is harder than 35?
The bottom line is wind is more than a number. A low number does not guarantee a success, and a higher number does not guarantee a failure (within reason). Everything depends on those other factors.
For landing, my approach now is to ask myself first whether the ground handling will be safe in this aircraft. If so, then I will try a low approach and see if the air handling feels safe. If I have enough rudder to stay aligned with the centerline, and the airplane feels under control, and the gust factor is reasonable, I’ll try the landing. If anything goes bad even during the rollout, I am ready to go around. Fly it all the way to the chocks.
If there’s anything else I’ve learned, it’s that over-confidence is another hazardous attitude. The invisible hand deserves respect, or it will smite thee.
- Wind is More than a Number - July 15, 2024
- Insidious failures: don’t trust, verify - May 25, 2022
This article is so true: I recently had a trip out to lunch where I landed a 182 with a 23 knot direct cross. I wrestled it all the way to the ground, landed pretty smoothly on one wheel then the other, and done. A few days later in a different plane, I “crash” landed with a float and a hop with a 9 knot cross. Why? Because I was too slow and my sight picture was off going from a high-wing to a low-wing a day or two later.
Another story: I asked a CFI friend of mine with a zillion hours dual given, “What’s your minimum for cross in a 172?” He said. “Around 15 knots.” I was shocked since I know he can land it with more than 15 knots direct. But his response was, “Why would I want to?” He’s right, you know.
There is this competitive aspect online and in hangars about how much wind one can handle – some kind of badge of courage and all that. The truth is the smart pilot finds a runway that agrees with the wind not the other way around.
This article needs some RUDDER remarks: “As soon as all three wheels are on the runway, only the wheels are counteracting the side force from the wind.” The RUDDER, with the help of nose wheel steering and differential braking keeps the airplane from weathervaning. This is particularly true with a castering (non-steering) nose wheel.
Also: “In a left crosswind you need right rudder during your sideslip, then once on the ground you need LEFT RUDDER…” !!!!! LEFT RUDDER means displacing the RUDDER to the left. This action will turn the airplane into the wind with undesirable results. You may have meant to say that a pilot may have to modify the amount of rudder displacement to keep the nose straight after landing.
Hey Mike, my comments on rudder were for a steerable nosewheel aircraft i.e. C172 or the like, which I should have clarified.
In a strong left crosswind, I use left rudder (just after landing) to allow weathervaning to the left otherwise the aircraft will skip entirely off the runway to the right. There is not enough weight on the wheels at this time for differential braking to do any good and if there is, it would flat spot the tires. I am curious what undesirable results you refer to with left rudder?
Adrian,
A steerable nosewheel airplane (C172) can depart the left side of a runway after landing with a strong left crosswind if the pilot applies left rudder after touchdown. The crosswind is applying a force to the vertical stabilizer to turn into the wind. Your recommended left rudder application is turning the airplane into the wind. At the same time the nosewheel is displaced to the left which turns the airplane into the wind. Result: the airplane departs the left side of the runway heading into the wind.
“In a left crosswind you need right rudder during your sideslip, then once on the ground you need left rudder to correct for the skipping and keep the aircraft centered.” You shouldn’t be skipping – I think you need to work with a CFI to see why you are skipping.
Adrian,
Just a lot of very good information tucked into your article. Nicely done!
Many could find it helpful.
Bill
Am I missing something? Nobody is mentioning using left aileron to help prevent skipping.
Tell us more – you use that after landing when all three wheels are already on the ground? How does that help?
Aileron is used primarily to keep the wing level. I assume it increases pressure against the runway for the upwind main but decreases for the downwind main. Adrian – are you possibly holding back pressure resulting in the weight of the airplane not settling completely against the runway resulting in the skipping?
When in the sideslip you’re cross controlled with left aileron/right rudder and may even touchdown on left main only. Anyway, as speed slows after touchdown you increase left aileron to maintain effectiveness, eventually to full left if wind strong enough. Right rudder to maintain centerline until nosewheel touches down, then as needed. It’s the same thing in reverse for takeoff isn’t it? (I think I remember skipping one time on takeoff until I applied more aileron.) I just don’t see how changing the rudder direction from straight after touchdown helps correct skipping other than “crabbing” to decrease the crosswind component. I guess all I’m saying is aileron into the crosswind decreases the side load and thus the skipping.
In a left cross wind bank left wing into wind or crab and right rudder to keep line up with runway all the way to touchdown and keep it in even if your on left wheel skipping comes from to much speed and not enough left aileron keep it on one wheel it will never skip keek corrections in till slow down and right wheel drops use right rudder to keep longitudinal axis lined up to RWY remember that prevented side load on landing gear it was a question in our privet pilot written that sometimes means landing on up wind landing gear in strang left cross wind no skipping
Don’t forget cross wind component your plane is not meant to land if your over it choose a different airport your going to skip porpoise balloon book a CFI