Crab landings in X wind question. Speed?

LongRoadBob

LongRoadBob

Cleared for Takeoff
Joined
Feb 26, 2016
Messages
1,393
Location
Oslo, Norway
Display Name
Display name:
Jacker
Was thinking about the crab method of landing in crosswind, and realize I'm missing something about it.
If you have for example a 20 knot crosswind at 30 degrees (I think thirty degrees means you halve the crosswind for the actual X wind component?) so 10 knots crosswind.

And decide to crab into the wind to land. I'm getting kind of hung up on what that means for your landing speed? Or actually even what speed difference, if any, you would have to use to keep on the centerline?

The main thing, to keep on the centerline on landing, can you do this at normal landing slow speed? When you kick over (with just rudder? Trying to keep the wing into the wind lower?) are you coming in significantly faster than you would in a still, no wind day?

There is something, maybe a few things, that I can't get my head around here.
 
It means exactly nothing for your standard IAS landing speed unless there is the need for an equally standard gust factor adjustment.

The headwind (or tailwind) component of the crosswind will, of course, affect your ground speed in exactly the same way it always does, even in cruise.

Missing? Not sure. Overthinking a bit maybe? Difference between airspeed and ground reference? "Crab and kick" is just the same crabbing into the wind you do when you fly cross country or on final before the slip to stay on track, followed by a later application of the same wing low method the pilots who slip all the way use. "Slip all the way" and Crab and kick" are just different points in a continuum, don't recall different techniques.
 
Last edited:
Thanks, I probably am overthinking. I tend to do that. Your answer makes sense, but even there, as one crabs to keep a heading when the air mass is crossing, even though IAS will be the same, there must be a speed that is not enough to keep your heading (relative the ground). Since landing is a transition from air to ground and while in the air IAS is most significant, when you cross to landing ground speed is also, right?

I guess I'm still confused, I feel like slipping to land makes "sense" in that the plane is slipping toward the wind but that is using the planes weight, so no need for a certain forward speed, where crabbing relative the ground does need a vector speed that would translate to forward speed after aligning.

I have a tangent question that has been gnawing at me too. I am understanding that throttle/thrust is in normal flight used for altitude, and attitude is setting speed. I have flown in slow flight, and it makes sense...but it is like going back and forth on the throttle and stick to get slow and fly. So IF I wanted to fly straight ahead at the fastest possible speed, would that be full throttle and a slightly nose down attitude (for keeping from climbing)?
 
You're overthinking. Fly the plane on the IAS numbers the same regardless of the crosswind technique. Alter IAS for gust factor. Keep it simple.
 
jordane93 said:
Speed stays the same unless there are significant winds.
Click to expand...
IAS stays the same unless there are significant GUSTS. This is important. Hot landings, student pilots, and winds leads to porpoising and broken airplanes.

I've landed in 30 knot winds with minimal gusts, 50 deg left of runway heading (Lancaster, CA -- not unusual conditions in summer afternoons). I did it at the same 61 KIAS I always do, in a 172. It just took bloody forever due the slow ground speed. And of course the landing was very short.

You will need more throttle to stay on a glideslope indicator, or an earlier base turn than usual. But NOT more airspeed.
 
If I'm flying in a strong crossing wind the primary thing I do differently is to fly a steeper final leg. I'll cheat the nose to the wind when possible but since the ground speed is reduced I adjust my position so I have a normal descent by time, not lateral space. Trading altitude for airspeed is a gust management safety tool. Adjust pitch to control airspeed and throttle to control the descent. Since your ground speed is reduced you won't cover as much ground as on a calm day. Make your turn to final closer in but at the normal altitude.

Get an instructor to go flying with you on a windy day.
 
Any airspeed in excess of what's needed for gusts can have at least two deleterious effects:

1) More time floating down the runway in the flare, giving gusts more time to upset things.

2) To avoid 1, a pilot may try to force the plane onto the runway fast and flat, possibly leading to a bounce and/or porpoising.

A little extra will likely have no ill effects, but I think many pilots get carried away and get into trouble that way.
 
If a guy flies a familiar calm day final leg using normal ground references and positions, the only way he can manage that sight picture in wind is to use a higher airspeed-lower rate of descent and subsequently touch down at a higher ground speed.

Get an instructor and learn to fly in the wind.
 
Stewartb said:
If a guy flies a familiar calm day final leg using normal ground references and positions, the only way he can manage that sight picture in wind is to use a higher airspeed-lower rate of descent and subsequently touch down at a higher ground speed.

Get an instructor and learn to fly in the wind.
Click to expand...
Huh? That's certainly not the only way.

You can land cleaner (less flap), or more appropriately, use more throttle, to maintain the same ground track.
 
LongRoadBob said:
I guess I'm still confused, I feel like slipping to land makes "sense" in that the plane is slipping toward the wind but that is using the planes weight, so no need for a certain forward speed, where crabbing relative the ground does need a vector speed that would translate to forward speed after aligning.
Click to expand...

You need to re-program your brain a bit. Forget about "forward speed" and slipping vs. crabbing. You need to think in terms of ground track. It doesn't matter whether you're crabbing or slipping on approach. In order for the airplane to fly a path along the ground that matches the runway track, the airplane needs to fly at a different path through the air (compared to the ground) in order to compensate for the x-wind. If there is a left x-wind, your path through the airmass must be a little toward the left in order for the airplane to remain over the runway as the wind blows.

Crabbing is simply selecting a ball-in-center coordinated flight heading that produces a desired path across the ground. If you are crabbing on final, and tracking the runway in a x-wind, changing to a slip to align the nose with the runway changes neither your flight path or your "forward speed", it just changes your heading...as in the direction the nose points. No different than if you're flying along x-country on a particular heading on a windless day and all of a sudden decide to yaw the nose and apply opposite aileron to keep the airplane from turning. You're still flying the same path through the air AND across the ground, and have changed neither your airspeed nor ground speed. Your nose simply points a different direction. This is all you're doing at some point before touching down in a x-wind.

You fly your normal indicated approach speed. The faster an airplane flies on final, the less difference is needed between the path through the air and the desired path across the ground. In other words, for a given amount of wind, your crab angle is less the faster you fly. You compensate for this with your eyeballs. As you round out and bleed speed off before touchdown, you must increase your x-wind correction in order to avoid drifting off centerline before touching down. But also keep in mind that wind velocity typically diminishes the closer you get to the runway. The x-wind correction needed at 100' AGL will likely be more than what's needed as your round out for landing.

Again, you look through the windscreen and manipulate the controls however is needed at any point to make the world outside the windscreen behave properly.
 
Last edited:
LongRoadBob said:
Thanks, I probably am overthinking. I tend to do that. Your answer makes sense, but even there, as one crabs to keep a heading when the air mass is crossing, even though IAS will be the same, there must be a speed that is not enough to keep your heading (relative the ground). Since landing is a transition from air to ground and while in the air IAS is most significant, when you cross to landing ground speed is also, right?
Click to expand...
Well sure. If your speed through the airmass is slower than the airmass movement across the ground, the airmass wins. But that's true for a headwind also. Try to land at 65 KIAS into a 70 KT direct headwind and you probably will have some trouble since you'll be moving backward relative to the ground. Make no mistake though, you are absolutely flying forward through the air.

I have a tangent question that has been gnawing at me too. I am understanding that throttle/thrust is in normal flight used for altitude, and attitude is setting speed. I have flown in slow flight, and it makes sense...but it is like going back and forth on the throttle and stick to get slow and fly. So IF I wanted to fly straight ahead at the fastest possible speed, would that be full throttle and a slightly nose down attitude (for keeping from climbing)?
Click to expand...
Don't get too hung up on that. It's great fodder for religious arguments. When you have both to work with, pitch and power are just two sides of the same coin. You coordinate them every time you make a change. They are just two ways of conceptualizing the exact same thing. Some just feel one is more helpful than the other (usually based on the way their instructor taught it, backwards ad infinitum.

Yes, to go as fast as you can in level flight, you will be full throttle with a slightly nose-down attitude compared to a slower cruise speed. But it doesn't matter whether you think of it as pitching down for the faster speed and powering to maintain altitude or pitching to maintain altitude and powering to increase the speed, so long as you end up doing both.
 
LongRoadBob said:
Thanks, I probably am overthinking. I tend to do that. Your answer makes sense, but even there, as one crabs to keep a heading when the air mass is crossing, even though IAS will be the same, there must be a speed that is not enough to keep your heading (relative the ground). Since landing is a transition from air to ground and while in the air IAS is most significant, when you cross to landing ground speed is also, right?...
Click to expand...
As Midlife said, the speed that is not enough to crab into the crosswind and hold the runway is the crosswind component of your airspeed. For practical purposes, you're not going to run into that limit. For a ridiculous example, think about a 90deg.(to the runway) crosswind at 65 knots. at 65 knots air speed, you can hold the runway with that, it would be a spot landing sideways to the runway with 0 ground speed. You'd never land in those conditions(I hope). The limit that you're going to run into before that is ever a factor is the max crosswind correction available with the rudder, if you've got the rudder deflected to the stop to counter the crosswind crab, and you're still crabbed into the wind, you are past the limit.
 
FastEddieB said:
Any airspeed in excess of what's needed for gusts can have at least two deleterious effects:

1) More time floating down the runway in the flare, giving gusts more time to upset things.

2) To avoid 1, a pilot may try to force the plane onto the runway fast and flat, possibly leading to a bounce and/or porpoising.

A little extra will likely have no ill effects, but I think many pilots get carried away and get into trouble that way.
Click to expand...

As a devout member of the @FastEddieB religion of "slower the better" for a safer landing, I'd be interested to see exactly how much you would recommend adding during gust factors? Do you just use the popular 1/2 of gust factor increase?
 
You can land in a crosswind until you are out of rudder.

That's the max. So it depends on how much rudder the plane has (my Husky has LOTS, up to 35knots worth). Remember, you have taxi too. Whats hard about taxiing is turning downwind. And near 90 degrees to wind is where you are most vulnerable to flipping.
 
So this happened to me a month ago. We had 20G30 perpendicular to the runway. I was fine until (this is what I think happened) I caught a gust, and it weather vaned into the wind. I had the rudder on the floor trying to keep the slip in. So, I went around. Second time, I set half flaps and did the "+ half the gust factor", landed on the upwind side of the runway, and was prepared to float for as long as necessary until I could get in between the gusts.

If you have the runway (and I did, +10000ft), wouldn't landing faster increase rudder effectiveness, at least for a little while? I've always established the slip on short final and held it to the runway. This lets me feel out the wind and seems more "stabilized". But now, I'm wondering if the "crab and kick" in gusty conditions would be better, since I could try to time it between gusts.

(I normally have no problems with xwind landings, but 20G30 90 degs to the runway is unusual.)
 
You cannot weathervane while airborne. You must have at least one wheel on the ground to do that. You had a yaw moment from something else, probably an eddy (especially if there were buildings upwind). Maybe shadowing from trees and a somewhat late rudder release.

You can't land faster without landing flat or on the nosegear. You can approach faster, but all that does is prolong the float. Your rudder will be more effective on the approach, but not where you really need it.

A somewhat flat landing in squirrely conditions may be called for, but you do still have to land on the mains. And you want the landing to be firm and authoritative -- the LAST thing you want is a bounce or long float. That means slower speeds.
 
Crosswind technique for me includes full flaps and the slowest airspeed I can manage. My strip is obstructed on three sides by tall trees and the surface is 15' wide. So far, so good. Mechanical turbulence is the variable that keeps me on my toes.
 
Mistake Not... said:
I've always established the slip on short final and held it to the runway. This lets me feel out the wind and seems more "stabilized". But now, I'm wondering if the "crab and kick" in gusty conditions would be better, since I could try to time it between gusts.
Click to expand...

I prefer the crab & kick and it's the technique I've always used. I don't like the feeling of being uncoordinated in gusty winds, while being low to the ground, so I never slip it in. Flying final with the nose crabbed, while tracking the runway laterally, allows for the winds to be felt. Once over the runway, kick out the crab and dip the downwind aileron. Give it some practice!
 
neilw2 said:
As a devout member of the @FastEddieB religion of "slower the better" for a safer landing, I'd be interested to see exactly how much you would recommend adding during gust factors? Do you just use the popular 1/2 of gust factor increase?
Click to expand...

In real life, I just add "a bit", though that's probably based originally on your rule of thumb above.

As a reminder, you can nibble away at the crosswind by landing at an angle across the runway into it.

Not a great example, but the video below gives an example of both some extra speed and an angle across the runway to handle a gusty crosswind:


Feel free to fast-forward to about a minute in for the final approach and landing. And I think the yaw string tells a story.
 
You guys make this too hard. 1.2 Vso in no wind. Half the gust factor if windy. Use TACH to set approach speed and stop eye-balling the ASI near the flare (you're landings will improve when you're eyes aren't on the ASI). My CFI took away the ASI and made me land by tach early on ... makes losing the ASI a non-event.
 
LongRoadBob said:
I'm getting kind of hung up on what that means for your landing speed?
Click to expand...

Did a 10kt cross-wind landing this morning. The King school method works well. Align on the centerline by nudging the upwind wing down just enough to stay lined up then finish off over the numbers with a slight rudder push to align the nose prior to touchdown. You may land on one wheel but all else is the same as a calm wind landing. No extra speed. No crab.
 
MAKG1 said:
You cannot weathervane while airborne. You must have at least one wheel on the ground to do that. You had a yaw moment from something else, probably an eddy (especially if there were buildings upwind). Maybe shadowing from trees and a somewhat late rudder release.
Click to expand...

Gust, not steady state. If I'm hit with a gust from the side, I find it hard to believe there would be zero net torque. What aerodynamic magic is causing that? Honest question, 'cause my physics-fu isn't what it used to be. In equilibrium (steady wind, unaccelerated plane), sure. I can see that. But a gust? From the side?

Would an analogous situation be the same plane at rest on a frictionless surface? Because it seems like if so, the plane would turn into the wind at least a little as it begins to slide sideways.
 
danhagan said:
You guys make this too hard. 1.2 Vso in no wind. Half the gust factor if windy. Use TACH to set approach speed and stop eye-balling the ASI near the flare (you're landings will improve when you're eyes aren't on the ASI). My CFI took away the ASI and made me land by tach early on ... makes losing the ASI a non-event.
Click to expand...
My students don't solo until then can land with no ASI. But I also have no idea what tach has to do with it.
 
Tarheelpilot said:
To the OP how far along in your training are you?
Click to expand...

Not very. I have still only around 11 hours flying time. Have been sick for a while, and two other factors, that I am getting closer to solo and rules here are one has to have taken (and passed at least certain subjects) the exam before being allowed to solo, and weather here.

So I've been stalled at the moment. Am trying to shake this fatigue and get cracking on Navigation. Hopefully can take the exam within a few months.
Then it is to book as much flying time as I can.
 
danhagan said:
You guys make this too hard. 1.2 Vso in no wind. Half the gust factor if windy. Use TACH to set approach speed and stop eye-balling the ASI near the flare (you're landings will improve when you're eyes aren't on the ASI). My CFI took away the ASI and made me land by tach early on ... makes losing the ASI a non-event.
Click to expand...

Horrible advice for a beginner who hasn't soloed yet!

OP, ask your CFI and work with them. The advice you will get here is worth what you paid for it.
 
neilw2 said:
As a devout member of the @FastEddieB religion of "slower the better" for a safer landing, I'd be interested to see exactly how much you would recommend adding during gust factors? Do you just use the popular 1/2 of gust factor increase?
Click to expand...

That's what is generally used. Myself I land without adding a gust factor and/or more speed, partial flaps, etc etc. IOW a normal airspeed full flapper. :D
 
mscard88 said:
That's what is generally used. Myself I land without adding a gust factor and/or more speed, partial flaps, etc etc. IOW a normal airspeed full flapper. :D
Click to expand...
A 15 knot gust suddenly quitting can take you from a nice short field landing to a stall. The gust factor can be important.
 
midlifeflyer said:
But I also have no idea what tach has to do with it.
Click to expand...

Me either. Never even looked at the tach unless it was required to log it each flight at a few places I rented from. And of course show a student pilot where, and what, it is used for.
 
MAKG1 said:
A 15 knot gust suddenly quitting can take you from a nice short field landing to a stall. The gust factor can be important.
Click to expand...

That's why my hand is always on the throttle. Has worked well for me for 41+ years, little planes to airliners.
 
That's why you fly it a little higher-steeper. Lowering the nose is the response to hold off a stall. A final leg in gusty swirling winds is a little like riding a rocking horse. Pitch controls airspeed.
 
LongRoadBob said:
Not very. I have still only around 11 hours flying time. Have been sick for a while, and two other factors, that I am getting closer to solo and rules here are one has to have taken (and passed at least certain subjects) the exam before being allowed to solo, and weather here.

So I've been stalled at the moment. Am trying to shake this fatigue and get cracking on Navigation. Hopefully can take the exam within a few months.
Then it is to book as much flying time as I can.
Click to expand...
It seems you chose your user ID wisely. ☺
 
danhagan said:
You guys make this too hard. 1.2 Vso in no wind. Half the gust factor if windy. Use TACH to set approach speed and stop eye-balling the ASI near the flare (you're landings will improve when you're eyes aren't on the ASI). My CFI took away the ASI and made me land by tach early on ... makes losing the ASI a non-event.
Click to expand...
1.3 to 1.5 Vso is preferable for new students and forms the basis for normal landing guidance in aircraft POHs.

Flying by reference to tach assumes the pilot is paying close attention to his pitch attitude, which is almost never the case with new students. A constant power setting and a failure to manager pitch is a recipe for disaster.
 
You must log in or register to reply here.
Back
Top