Engine out thought

[flyingcheesehead]

Unless said crosswind exceeds your rudder authority and you cannot maintain your course on final.

Then crab. When you get into ground effect, where the winds are usually lighter as you said, you'll be able to kick out of the crab and slip in the flare without having any extra speed to bleed off.

 

[EdFred]

Read the initial premise @steingar stated. Winds steady/gusting at higher velocity at 100ft AGL then on the runway. Often see this on the coasts where tree lines break up the wind near the runway.
My assumption is @steingar prefers to slip instead of crab down through the cross wind; which does have limits on rudder authority.

Tim

If you are Vref + 20 when you cross the numbers you are using bad technique unless the winds are 20G60.

 

[denverpilot]

A CFI had me do a power off 180 with the gear down in an Arrow; during a BFR or club flight check, I forget which. Man was that descent rate an eye opener.

The famous drawing from someone via the Internet...

 

[tspear]

@flyingcheesehead @EdFred
Crab works great in VMC. Much harder when flying IFR.
Is it something to use often, I hope not However, like @steingar it is one more tool in the toolbox.

Tim

 

[jspilot]

Let's look at this mathematically, since I think the results will surprise you.

If you look at post #60 - In that scenario (based off the OP but with extra specifics), if I'm over the numbers at 500 feet with a tailwind, I have three options: Attempt a downwind landing straight in from current position, attempt a 360 to a downwind landing, or attempt to turn around and land upwind, ideally via a teardrop maneuver. A full pattern, of course, is foolish.

Intuitively, I think I would go for option 3. Groundspeed would be pretty quick at first, and we could start the turn prior to being abeam the threshold to ensure we could make the runway.

If I'm over the numbers at 500 feet with a tailwind and attempt the straight-in downwind landing, my touchdown would be 5,738 feet down the runway, which is to say I would touch down 2,738 feet past the runway if there were no obstacles. In reality, I'd still be 195 feet in the air when passing over the obstacles past the opposite end of the runway, and I'm dead. So, the straight-in downwind landing from 500 AGL at the numbers is definitely a no-go unless you have over 7,000 feet of runway available.

Second scenario, 360 to a downwind landing. We have 40 seconds until we meet terra firma, so we need our turn rate to be triple standard rate, which will require a bank angle of 26.33º, but that's going to increase drag and hasten our meeting with terra firma, so we'll need to pull it around a bit quicker, probably a 30-35º bank angle to make it back around by touchdown. This is a viable option. Keep in mind that a constant bank angle will result in us not landing at the threshold, but about 1,687 feet down the runway, so we're going to go off the end of the runway (again, see post 60). A perfect turn about a point will have us flying at a much higher bank angle at the beginning and end of the turn, increasing the chances of a stall and making the landing very difficult. But, this is a viable option and survivable.

Finally, for the third scenario, assuming the wind is right down the runway, we could offset to either side while flying downwind and make a 180 to land upwind. Let's say we spend half the 40 seconds flying and half turning, so our turn will be very similar to the turn required for the 360 above. 20 seconds of flying downwind will take us 2869 feet from the starting point. We'll want to offset by the diameter of the turn (or twice the radius) so that we're over the runway at the end of the turn. Going with a 30º bank, our turn radius will be 553 feet so we'll want to offset by 1106 feet. Since we're flying the hypoteneuse of the triangle, that means we'll need to turn 22.6 degrees off runway heading to get our offset, and it'll place us abeam a point 2,647 feet down the runway. The wind will push us an additional 843 feet down the runway during the turn, thus we would come up 490 feet short. However, an increased angle of bank early in the turn is safer here as we don't need the higher bank near the ground due to facing into the wind as we approach the ground. So, we could decrease the offset slightly and crank it around a bit on the high side and have an easier approach. In any case, this scenario is survivable as well.

Now, let's throw a crosswind into the mix. Let's say that 25 knots is now 45 degrees off runway heading. First scenario is still fatal. For the second scenario, our 360 maneuver is made more difficult - If we start the turn away from the crosswind to keep the highest bank angles further above the ground, we're going to have a headwind as we come around to the base-to-final portion and we might not make it. We certainly will have eliminated any additional options should we come up short. If we instead begin the turn into the crosswind, we'll need to have our highest bank angle as we're completing the turn near the ground, which is even more risky as we may well hit a wingtip and cartwheel, which is likely to result in serious injuries at least.

But, the "teardrop" is actually helped by the crosswind. Instead of making a turn to offset, we can fly the runway heading. If we fly that heading for 20 seconds again, the wind will blow us 597 feet to the downwind side before the turn, and if we do the same 20-second turn we'd be a total of 1194 feet to the side, except our turn radius will take us 1106 feet back toward the runway, so the 20 seconds straight + 20 second turn puts us 88 feet downwind of centerline. So, the better option is to just fly runway heading for more like 15 seconds, and then make our turn and we'll have a 5-second "final" into the wind. We also blow downwind a shorter distance, meaning we make the threshold without issue.

Let's say we do 15 seconds runway heading followed by a 25-second turn. After 15 seconds, we're 447 feet off centerline and 1,966 feet down the runway. At the end of the turn, we'll be 2,562 feet down the runway and 63 feet upwind of centerline. Of course, we've also turned around, so there's 2,562 feet of runway in front of us. Our 5-second final has us touching down 357 feet later, so we stop rolling with 1,950 feet of runway remaining in front of us. The crosswind also pushes us back toward the centerline, in fact we'll need to crab or slip a little bit on our short final to keep from being blown back across the centerline.

So, in this case, I know which one I'm doing! Of course, not all situations are equal, and we obviously don't have time to do these calculations in the air, so to both @jspilot and @PaulS, thank you for the opportunity to think this through thoroughly on the ground! We should be able to tell using normal pilot skills whether the downwind landing would put us past the end of the runway for the straight-in downwind landing, but the other options are not so intuitive.

I feel the urge to create a spreadsheet to make these scenarios easier to calculate so I can play around with them a bit...

As someone wisely once said, “experience is often what comes after it is needed!” In this case, we all have the option to gain some experience before it is needed. Thank you @flyingcheesehead for your amazing math work and valued contribution to the discussion!

 

[EdFred]

@flyingcheesehead @EdFred
Crab works great in VMC. Much harder when flying IFR.
Is it something to use often, I hope not However, like @steingar it is one more tool in the toolbox.

Tim

When you are tracking a course, you are always crabbing (unless you have the rare direct tailwind/headwind). Unless you are saying that when you fly IFR you try and fly your course by flying the same heading and slip the entire flight. You may want to rethink that.

When I'm in the goo and flying an approach, I don't give a crap if my heading doesn't match the course. I want to make sure I stay on the path - easiest way to do that is crab (wind correction angle).

 

[flyingcheesehead]

@flyingcheesehead @EdFred
Crab works great in VMC. Much harder when flying IFR.
Is it something to use often, I hope not However, like @steingar it is one more tool in the toolbox.

What? You're saying it's easier to slip when flying an instrument approach?!? No way. Crab is what we do when flying IFR, never heard of anyone being taught different than that.

Besides, @steingar is not instrument rated.

 

[3393RP]

The famous drawing from someone via the Internet...

.

Oh man...this drawing is fuggin' hilarious. "Sleeping presolo Gemini"...and the facial expressions in panel #4 are priceless.

 

[tspear]

I was taught both crab and slip for maintain final approach course.
Depending on the plane, I have found one easier than the other.

Tim

 

[EdFred]

I was taught both crab and slip for maintain final approach course.
Depending on the plane, I have found one easier than the other.

Tim

You were taught to slip *IN* IMC to maintain FAC? How is that easier?

 

[jspilot]

I’ve never trained for IFR but in my training days for my Private I was taught a crab is designed to maintain your desired ground track and a slip is designed to lose altitude. I’m confused why you’d slip to maintain centerline( the localizer) during IFR.

 

[tspear]

You were taught to slip *IN* IMC to maintain FAC? How is that easier?

You have three techniques. Slip all the way down, crab then slip, or crab to a kick when wheels touch. I have never been a fan of crab to kick, I find I am not good enough to judge it exactly and end up putting more side load than I like on the gear. That leaves the first two choices.

The faster the plane, the less time you get from 200ft AGL until wheels down. So in a piston twin (like the Aerostar), you do not deploy full flaps until the runway is made. So you are going from 120 KIAS down to 90 KIAS, changing pitch angle, and changing power. Adding in the transition from a crab to slip makes life rather interesting and complicated.

Also, if the crab angle is pretty good, moving your head and eyes from your panel scan to the side to look out the window, is rather more difficult to judge where exactly to do so, and increase chance of vertigo since your eye movement and inner ear are even more out of sync.

I have used both slip all the down and crab then slip. I practice both, but depends on the plane which I use outside of practice.

Tim

 

[tspear]

I’ve never trained for IFR but in my training days for my Private I was taught a crab is designed to maintain your desired ground track and a slip is designed to lose altitude. I’m confused why you’d slip to maintain centerline( the localizer) during IFR.

Technically, I am pretty sure the technique is called a side slip. You are using the horizontal component of lift by rolling the wings to the side to counter the effect of a cross wind. You then are using the rudder to maintain heading.
At the same time, you normally have to increase power some, and depending on the plane pitch up a touch to avoid losing to much altitude.

Tim

 

[denverpilot]

I want to see someone fly it as accurately (down to the foot) as @flyingcheesehead ‘s math.

 

[wayne]

The famous drawing from someone via the Internet...

That's so funny. When I was writing about the Arrow power off 180 I was thinking about comparing it to a sack of hammers falling. Hmm, which would get to the ground first?

 

[PaulS]

Let's look at this mathematically, since I think the results will surprise you.

If you look at post #60 - In that scenario (based off the OP but with extra specifics), if I'm over the numbers at 500 feet with a tailwind, I have three options: Attempt a downwind landing straight in from current position, attempt a 360 to a downwind landing, or attempt to turn around and land upwind, ideally via a teardrop maneuver. A full pattern, of course, is foolish.

Intuitively, I think I would go for option 3. Groundspeed would be pretty quick at first, and we could start the turn prior to being abeam the threshold to ensure we could make the runway.

If I'm over the numbers at 500 feet with a tailwind and attempt the straight-in downwind landing, my touchdown would be 5,738 feet down the runway, which is to say I would touch down 2,738 feet past the runway if there were no obstacles. In reality, I'd still be 195 feet in the air when passing over the obstacles past the opposite end of the runway, and I'm dead. So, the straight-in downwind landing from 500 AGL at the numbers is definitely a no-go unless you have over 7,000 feet of runway available.

Second scenario, 360 to a downwind landing. We have 40 seconds until we meet terra firma, so we need our turn rate to be triple standard rate, which will require a bank angle of 26.33º, but that's going to increase drag and hasten our meeting with terra firma, so we'll need to pull it around a bit quicker, probably a 30-35º bank angle to make it back around by touchdown. This is a viable option. Keep in mind that a constant bank angle will result in us not landing at the threshold, but about 1,687 feet down the runway, so we're going to go off the end of the runway (again, see post 60). A perfect turn about a point will have us flying at a much higher bank angle at the beginning and end of the turn, increasing the chances of a stall and making the landing very difficult. But, this is a viable option and survivable.

Finally, for the third scenario, assuming the wind is right down the runway, we could offset to either side while flying downwind and make a 180 to land upwind. Let's say we spend half the 40 seconds flying and half turning, so our turn will be very similar to the turn required for the 360 above. 20 seconds of flying downwind will take us 2869 feet from the starting point. We'll want to offset by the diameter of the turn (or twice the radius) so that we're over the runway at the end of the turn. Going with a 30º bank, our turn radius will be 553 feet so we'll want to offset by 1106 feet. Since we're flying the hypoteneuse of the triangle, that means we'll need to turn 22.6 degrees off runway heading to get our offset, and it'll place us abeam a point 2,647 feet down the runway. The wind will push us an additional 843 feet down the runway during the turn, thus we would come up 490 feet short. However, an increased angle of bank early in the turn is safer here as we don't need the higher bank near the ground due to facing into the wind as we approach the ground. So, we could decrease the offset slightly and crank it around a bit on the high side and have an easier approach. In any case, this scenario is survivable as well.

Now, let's throw a crosswind into the mix. Let's say that 25 knots is now 45 degrees off runway heading. First scenario is still fatal. For the second scenario, our 360 maneuver is made more difficult - If we start the turn away from the crosswind to keep the highest bank angles further above the ground, we're going to have a headwind as we come around to the base-to-final portion and we might not make it. We certainly will have eliminated any additional options should we come up short. If we instead begin the turn into the crosswind, we'll need to have our highest bank angle as we're completing the turn near the ground, which is even more risky as we may well hit a wingtip and cartwheel, which is likely to result in serious injuries at least.

But, the "teardrop" is actually helped by the crosswind. Instead of making a turn to offset, we can fly the runway heading. If we fly that heading for 20 seconds again, the wind will blow us 597 feet to the downwind side before the turn, and if we do the same 20-second turn we'd be a total of 1194 feet to the side, except our turn radius will take us 1106 feet back toward the runway, so the 20 seconds straight + 20 second turn puts us 88 feet downwind of centerline. So, the better option is to just fly runway heading for more like 15 seconds, and then make our turn and we'll have a 5-second "final" into the wind. We also blow downwind a shorter distance, meaning we make the threshold without issue.

Let's say we do 15 seconds runway heading followed by a 20-second turn and a 5-second "final". After 15 seconds, we're 447 feet off centerline and 1,966 feet down the runway. At the end of the turn, we'll be 2,562 feet down the runway and 63 feet upwind of centerline. Of course, we've also turned around, so there's 2,562 feet of runway in front of us. Our 5-second final has us touching down 357 feet later, so we stop rolling with 1,950 feet of runway remaining in front of us. The crosswind also pushes us back toward the centerline, in fact we'll need to crab or slip a little bit on our short final to keep from being blown back across the centerline.

So, in this case, I know which one I'm doing! Of course, not all situations are equal, and we obviously don't have time to do these calculations in the air, so to both @jspilot and @PaulS, thank you for the opportunity to think this through thoroughly on the ground! We should be able to tell using normal pilot skills whether the downwind landing would put us past the end of the runway for the straight-in downwind landing, but the other options are not so intuitive.

I feel the urge to create a spreadsheet to make these scenarios easier to calculate so I can play around with them a bit...

Too tired tonight to go through your analysis and when I do go through it, it may change my mind, but, in my assumption the pilot has flown at best glide to get to 500 feet above the "wrong end" runway, facing downwind. While it may be possible to make a landing, upwind, from this point, I doubt I would attempt it. Rather than maneuvering in a low energy state, not sure I would be able to complete the maneuver, I would instead realize how lucky I am to arrive at a runway, with the potential to be 500 feet high, at the threshold pointing downwind, meaning I would have plenty of time and energy to bleed, well before I got to that threshold. I could be on a high final, with full flaps and slip to put the wheels on the threshold, albeit pointed down wind, with plenty of room to get stopped. I like that option.

 

[steingar]

Crosswinds can exceed rudder authority in a crab. BTDT. Steingar is not IFR rated yet.

 

[jsstevens]

Crosswinds can exceed rudder authority in a crab. BTDT. Steingar is not IFR rated yet.

How? You just point the plane further into the wind. In fact, you can fly completely coordinated in a crab up until the plane is pointed directly into the wind. Then if the wind is faster than your TAS, you go backwards (relative to the ground) but still fully coordinated. All a crab is is changing the heading of the plane more into the wind until you achieve the desired ground track.

You can run out of rudder authority in a side slip, sure. But a crab? I'm genuinely puzzled what you mean.

John

 

[EdFred]

Crosswinds can exceed rudder authority in a crab. BTDT. Steingar is not IFR rated yet.

Based on that statement, I don't think you know what a crab is. There is no rudder used while crabbing.

 

[Bill Watson]

Based on that statement, I don't think you know what a crab is. There is no rudder used while crabbing.

I absolutely agree. However people sometimes confuse a slip with a crab.

(I’m going to purposely not use the terms ‘forward’ or ‘side’ to describe types of slips because I can never remember which is which... but I know how to fly both. However a slip always requires cross controls - that’s the definition I’ll use)

Imagine an experienced pilot turning base. They already have a sense of the wind including the crosswind component on final. They make a coordinated turn onto final and when they roll out their nose is pointed towards the crosswind, the wings are level and they are tracking straight down the final approach course in coordinated flight. This is a crab. Any changes in the wind are compensated for by small coordinated turns and a quick return to level coordinated flight at the required crab angle. This can be maintained until just before touchdown when the rudder can be used to align the center line of the plane withe the centerline of the runway. It can be tricky, it’s never perfect, but airliners do it all the time.

Alternatively, at any point before touchdown, the same pilot can decide to use a slip to align the centerlines. This requires crossing the controls using the rudder to align centerlines and opposite aileron to maintain the ground track. This can be done at any time during the final approach and when done right will result in the upwind wheel rolling on , followed by the downwind wheel. It can be perfect and is not tricky once mastered and proficiency is maintained.

Now imagine the student pilot learning crosswind techniques. They turn final with the centerlines aligned but quickly realizes that they are drifting off the correct track. They decide to use a ‘crab’ to correct. So the use rudder to get the nose into the wind, and instinctively use aileron to keep the wings level. It works but the are in a slip with crossed controls. However this often morphs into an actual crab after a few manipulations and the pilot finds themselves in coordinated flight, tracking down final still faced with the decision of when and how to get the centerlines aligned. No harm, no foul, just a bit sloppy.

Run out of rudder in a ‘crab’? Only in the case above where they are actually in a cross controlled slip. And you can definitely run out of rudder in a slip designed to align centerlines before touchdown.


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[Bill Watson]

If you are on speed and the gust factor or crosswind exceeds your rudder authority you can power up and go around. Without a working engine you may well be as good as dead, since you will loose control of the aircraft. Now with a faster approach air goes over the control surfaces with greater velocity. That increases the force that they can exert, increasing the authority of your rudder and ailerons. Now you can track straight against that nasty uncooperative wind. Problem is you'll be fast when you do get into the runway environment.

First, if you do porpoise and strike the prop, so what? Engine isn't making power anyway, and you're likely facing repairs no matter what you do (assuming you did things like carb heat, switch tanks and of course remember to bring along enough gas). Moreover, striking the prop beats CFIT any day. If you overrun, again beats the alternative. Unless your runway abuts a cliff whatever you hit is likely to be more forgiving than what you'd hit in an off airport landing.

If that's what happens to me when I bring my Mooney into that 3K foot strip with a 20 knot tailwind component, oh well. Airplane will be pranged, but odds are I'll be fine, if a bit bruised. If its a 5K foot strip I probably won't do any of that, even the Mooney will bleed off enough speed to land safely. They key is just a bit of airmanship, enough pitch up that you don't collide with the runway, not so much that you balloon. Just gently hold it off, let the speed bleed off and wait until you hit your landing speed and it settles down.

That said, I can count the number of times I had to use this technique on the fingers of one hand. Still, not the worst trick to have in your tool box.

The problem with carrying extra speed down in ground effect is that the extra speed is magnified by decreased drag in ground effect. This particularly true in low wing planes like the Mooney, less so in high wingers.

Yes you can easily hold it there and bleed off speed. It’s particularly easy to do in a Mooney which just loves to sit in ground effect, but you have extended your landing distance significantly. A seductive maneuver but completely wrong headed.


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[tspear]

The problem with carrying extra speed down in ground effect is that the extra speed is magnified by decreased drag in ground effect. This particularly true in low wing planes like the Mooney, less so in high wingers.

Yes you can easily hold it there and bleed off speed. It’s particularly easy to do in a Mooney which just loves to sit in ground effect, but you have extended your landing distance significantly. A seductive maneuver but completely wrong headed.

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Why is it "wrong headed"?
It is not something I have used much, but it was taught to me as one more technique/tool to have.

Tim

 

[Troska]

Why is it "wrong headed"?
It is not something I have used much, but it was taught to me as one more technique/tool to have.

Tim

Because it doesn't gain you anything except a longer float down the runway.

Tim

 

[steingar]

Because it doesn't gain you anything except a longer float down the runway.

Tim

You guys are all right about one thing. You can indeed crab into any kind of wind. However, surface winds can exceed your rudder authority when you go to straighten out to land. That's where coming in a bit faster can help you out, like I said greater control authority. Has delivered me from some bad winds. Yes, you are going to float a bit more. And yes, you'll have to deal with that wind when you do slowdown, but hopefully you'll be that much closer to the ground where it will be somewhat less, or maybe you'll luck out an hit a lull just as you're landing. Stranger things have happened.

All this said I still think the best option is to go elsewhere. If your engine has taken a dump and you're out of options? Whatever, get the aircraft down and stay safe. Who cares if the thing gets pranged, the insurance company owns it anyway. Get yourself and your pax out safely.

 

[tspear]

Because it doesn't gain you anything except a longer float down the runway.

Tim

Go back and read when to use it. It works, and it is useful. Albeit the situations to use it are kinda rare.

Tim

 

[Troska]

Go back and read when to use it. It works, and it is useful. Albeit the situations to use it are kinda rare.

Tim

I went back and read through your posts again. If there is a gust factor, I understand why you'd carry extra speed.

If there is no gust factor, I don't see the benefit in carrying extra speed just to float down the runway in ground effect.

Tim

 

[Troska]

You guys are all right about one thing. You can indeed crab into any kind of wind. However, surface winds can exceed your rudder authority when you go to straighten out to land. That's where coming in a bit faster can help you out, like I said greater control authority. Has delivered me from some bad winds. Yes, you are going to float a bit more. And yes, you'll have to deal with that wind when you do slowdown, but hopefully you'll be that much closer to the ground where it will be somewhat less, or maybe you'll luck out an hit a lull just as you're landing. Stranger things have happened.

All this said I still think the best option is to go elsewhere. If your engine has taken a dump and you're out of options? Whatever, get the aircraft down and stay safe. Who cares if the thing gets pranged, the insurance company owns it anyway. Get yourself and your pax out safely.

Steingar,

Unless you are saying that you are touching down in your Mooney at a higher-than-normal speed, you still have to transition through that speed of lower control authority as float down the runway at 2ft AGL.

Why not just fly the appropriate approach speed, you can still fly it in a slip to maintain alignment with the centerline as much as possible, and as you descend into lower crosswind component adjust your control input to correspond. You get the same thing without the float.

Tim

 

[steingar]

Steingar,

Unless you are saying that you are touching down in your Mooney at a higher-than-normal speed, you still have to transition through that speed of lower control authority as float down the runway at 2ft AGL.

Why not just fly the appropriate approach speed, you can still fly it in a slip to maintain alignment with the centerline as much as possible, and as you descend into lower crosswind component adjust your control input to correspond. You get the same thing without the float.

Tim

Like I said, I only use the higher speed if the winds are that squirrely that I run out of rudder. That said, I'm not going to do it on a runway that can't handle the float. And if I have power I am far more likely just to go elsewhere until the winds die down, which I think is the best course of action anyway.

This isn't really that big a deal anyway. As slick as the Mooney is, it can be dirtied up with flaps and gear. Once it is it will shed speed. One just has to be patient, and not try and paint the aircraft before its ready to stop flying. The fellow from whom I bought mine came in way too fast and did float, but was in no danger for floating off the end of the runway. I always use the correct approach speed because some day I might have to land it short, and I'd better bloody well be able to do so.

 

[tspear]

I went back and read through your posts again. If there is a gust factor, I understand why you'd carry extra speed.

If there is no gust factor, I don't see the benefit in carrying extra speed just to float down the runway in ground effect.

Tim

I cannot think of an airport off hand where I have used it; but the basic situation is that you have a strong crosswind down to 50ft or at most 100ft AGL. At which point the crosswind is mechanically disrupted, usually via a line of trees. If the crosswind is strong enough that you are going to turn more then 10/15 degrees it gets harder to align with the runway. Therefore, a slip is visually easier, especially if going to whip around a complex plane such as twin piston as you change configuration to land. However, a slip has limits in rudder authority....

Tim

 

[flyingcheesehead]

You guys are all right about one thing. You can indeed crab into any kind of wind. However, surface winds can exceed your rudder authority when you go to straighten out to land. That's where coming in a bit faster can help you out, like I said greater control authority. Has delivered me from some bad winds. Yes, you are going to float a bit more. And yes, you'll have to deal with that wind when you do slowdown, but hopefully you'll be that much closer to the ground where it will be somewhat less, or maybe you'll luck out an hit a lull just as you're landing. Stranger things have happened.

OK, here's what I'm missing. Let's say you have a crosswind from the left, you're coming down final in a crab, and when you straighten out to land - IE, when transitioning from roundout to flare - you're using *right* rudder (opposite the wind) to do so. If you don't use "enough" rudder, the turn to align the airplane's axis with the centerline is slower, possibly requiring more *aileron* to bank into the wind and correct for drift.

Where you can run out of rudder authority is in a slip, where you are putting your upwind wing down and using rudder to maintain heading. But again, I've never run out of rudder, even in a 35-knot direct crosswind.

So, let's go back to this "come in faster" myth. If, after you transition to cross-controlled flight in the flare at a normal approach speed, you don't have enough rudder authority to counteract the bank you're using to maintain centerline, coming in faster isn't going to help you. Sure, you'll be able to hold the plane over the centerline at faster speeds, but you're still going to have to slow down through your normal approach speed prior to touchdown, meaning you still won't have enough rudder authority - While you're faster, you will, but as you slow down you'll need to add rudder and if you didn't have enough prior to touchdown from a normal approach speed, you still won't have enough to maintain the centerline all the way to touchdown.

Unless you're transitioning from the crab to the slip well out of ground effect, coming in faster won't help you. And if you are, stop it. If the winds at the surface will allow for a crosswind landing but winds 50 feet up mean you run out of rudder, then just don't transition until you're in ground effect. @steingar, your "hopefully you'll be that much closer to the ground where it will be somewhat less" comment makes me think you're transitioning from crab to slip too early.

I don't use "always" and "never" much, but in this case I'll say it: Always approach at no more than normal approach speed for your actual landing weight plus half the headwind component of the gust factor. (And always use full flaps - But if we're gonna argue that, let's start a new thread.)

 

[tspear]

I don't use "always" and "never" much, but in this case I'll say it: Always approach at no more than normal approach speed for your actual landing weight plus half the headwind component of the gust factor. (And always use full flaps - But if we're gonna argue that, let's start a new thread.)

You start the thread, and the premise and I will see what I can do to argue a counter point.

Tim

 

[Bill Watson]

Like I said, I only use the higher speed if the winds are that squirrely that I run out of rudder. That said, I'm not going to do it on a runway that can't handle the float. And if I have power I am far more likely just to go elsewhere until the winds die down, which I think is the best course of action anyway.

This isn't really that big a deal anyway. As slick as the Mooney is, it can be dirtied up with flaps and gear. Once it is it will shed speed. One just has to be patient, and not try and paint the aircraft before its ready to stop flying. The fellow from whom I bought mine came in way too fast and did float, but was in no danger for floating off the end of the runway. I always use the correct approach speed because some day I might have to land it short, and I'd better bloody well be able to do so.

"Squirrely" winds are not going to be the reason you run out of rudder, it will simply be too great a crosswind component, possibly a gusty wind. Assuming we are talking about a trike, running out of rudder for a slip or misjudging the kick out of the crab will result in the same thing; a cloud of rubber and a jolt as the trike gear does it's thing and straightens the whole thing out allowing you to roll down the runway. Not pretty but not a loss of control even if structural damage is done.

Forcing it on, wheel barreling, porpoising, crushing the nose gear and banging the prop are all out of control situations that may result in getting hurt. Out of control even if the whole event starts with being perfectly aligned with the runway. The faster you are going the great the chance of hurt. Please don't do that, even in an emergency.

Not sure where you were going with "As slick as the Mooney is, it can be dirtied up with flaps and gear". I assumed you were landing so gear was down and some flaps were on. No matter what speed you intend to touch down at, the quickest way to that speed is to slow down outside of ground effect *especially* in a Mooney which really floats in ground effect even all dirtied up. That float is a function of the reduced drag and reduced drag means more distance to slow.

Flying a Mooney in ground effect is seductive because it is so easy to do but it can only benefit you if you need to extend a power out glide slightly to say, hit the threshold instead of thumping down in the grass just short. Otherwise it is just easy and comfortable to do.

However, there is more than a grain of truth in the whole 'speed up to gain control effectiveness' idea. In a tailwheel plane, it can be done and it works and it's called a wheelie. It's part of the reason that one might choose to do a 'wheelie' on a particular landing rather than a 3 pointer. And in fact, one can land at faster than normal speeds quite well using conventional gear. And the technique is routinely used to operate in crosswinds where there is not enough rudder effectiveness to land straight at normal touch down speeds. But it only works reliably with tailwheel, conventional gear aircraft. In a trike you can land crooked up to a point and the gear will straighten things out with a screech and a lurch. You can go to any training runway and watch this demonstrated all day long.

There is also a technique that will work quite well on many trikes to allow a faster than normal speed to be carried into touchdown. My guess is that it would work very well on the Mooney. I used to fly a glider (PIK-20b) where this technique was standard for every landing. Here it is: fly a faster than normal approach until in ground effect, float, and when the touchdown point is reached, retract the flaps while pitching up. You'll land right now, right there, under control. Try that instead of forcing it on and risking a porpoise, damaged nose gear or prop strike.

Hopefully, any aircraft you try the 'retract flaps while flaring' technique will have an easier to operate flap mechanism than my old PIK did. It had a crank which required 3-4 full rotations to get the flaps up from the 90degree approach setting. Try rubbing your stomach in a circular pattern with one hand while patting your self on the head with the other to get a feel for how that works. I was the gliderport's entertainment for half a season before mastering that one.

 

[Bill Watson]

OK, here's what I'm missing. Let's say you have a crosswind from the left, you're coming down final in a crab, and when you straighten out to land - IE, when transitioning from roundout to flare - you're using *right* rudder (opposite the wind) to do so. If you don't use "enough" rudder, the turn to align the airplane's axis with the centerline is slower, possibly requiring more *aileron* to bank into the wind and correct for drift.

Where you can run out of rudder authority is in a slip, where you are putting your upwind wing down and using rudder to maintain heading. But again, I've never run out of rudder, even in a 35-knot direct crosswind.

So, let's go back to this "come in faster" myth. If, after you transition to cross-controlled flight in the flare at a normal approach speed, you don't have enough rudder authority to counteract the bank you're using to maintain centerline, coming in faster isn't going to help you. Sure, you'll be able to hold the plane over the centerline at faster speeds, but you're still going to have to slow down through your normal approach speed prior to touchdown, meaning you still won't have enough rudder authority - While you're faster, you will, but as you slow down you'll need to add rudder and if you didn't have enough prior to touchdown from a normal approach speed, you still won't have enough to maintain the centerline all the way to touchdown.

Unless you're transitioning from the crab to the slip well out of ground effect, coming in faster won't help you. And if you are, stop it. If the winds at the surface will allow for a crosswind landing but winds 50 feet up mean you run out of rudder, then just don't transition until you're in ground effect. @steingar, your "hopefully you'll be that much closer to the ground where it will be somewhat less" comment makes me think you're transitioning from crab to slip too early.

I don't use "always" and "never" much, but in this case I'll say it: Always approach at no more than normal approach speed for your actual landing weight plus half the headwind component of the gust factor. (And always use full flaps - But if we're gonna argue that, let's start a new thread.)

I agree with everything said here.

But lets start and end the argument about full flaps. I would suggest that it is aircraft specific. In fact, the Maule POH specifies that reduced flaps should be used for high crosswind conditions, even reflex flaps! That is, the Maule's flaps can be set upward to a negative or reflex position. Strangely, according to both the factory demo pilot and my experience, the Maule is always most easily landed in the 3 point attitude, no matter what the wind, and even with reflex flaps. What you are doing is setting up a configuration where you are in what looks like a 3 point 'full stall' attitude but with reflex flaps you are in fact flying at a relatively flat angle of attack, and can therefore carry more speed without the excess lift that will cause floating.

 

[denverpilot]

@flyingcheesehead has an excellent point that needs to be amplified.

Whenever someone says they’re “flying faster for more control” in a crosswind, the correct next question is “And then you have to slow from there still, so how will you keep it straight in the transition phase, even after wheels touchdown, when a gust hits?”

If your answer is, “The runway is wide and I can buy new tires...” so be it, but in a typical trike, landing “faster for control” usually means two things:

1. You haven’t spent enough time slow in your aircraft.
2. You’ll arrive at the ditch sooner and going faster have no more control than the pilot who touched down as slow as they could.



Points noted about the tailwheel aircraft, but this concept can apply to those, too. Land in a two-point attitude and lose control slowing to a three point is a pretty common start to an into the ditch excursion.

If you’re going to “run out of rudder” it’s still going to happen if you touched down fast, it’s just going to happen during the roll out. And you’ll have SOME help from tire friction (or in the case of some tailwheel aircraft, a locking tailwheel plus friction... at least until the lock lets go if it’s one of those locked until you put enough side load on it sorts of locks).

But if you’re sliding sideways on the tires after touchdown and have side loads, that’s technically no more “in control” than not being able to hold the upwind wing down and the centerline straight with the flight controls... at any speed.

If you can’t get it straight when slow, it doesn’t matter what you can do ten knots faster. Some people plant it hard after a faster approach and then let tires and gear take on massive side loads, but that’s not really an under control landing, that’s just a bad one that didn’t meet the criteria for controllability. (They also often relax the controls and don’t have them fully locked over to the stops, either, which is a related problem but we’ll ignore it for the moment. But in the right/wrong conditions you’ll have a wing lift on the upwind side or a massive gust will weathercock the aircraft... sending you... to the ditch...)

One gust in that “tires barely holding it from sliding sideways” landing at the wrong time, you’re headed into the ditch unless you’re awfully quick at the go-around and have a wide enough runway to do it.

Landing rollout accidents and incidents are on the rise. Make sure you’ve REALLY thought about this if you’re saying landing faster is the best plan. It’s OFTEN a sign you need a bunch of really slow landings with a CFI in a stiff crosswind to just see how much you need to move the less effective (but not INEFFECTIVE) controls and you just don’t like the “sloppy” feel, more than it REALLY gives you “more control”.

In other words, you might just be SLOW on your controls because you forgot they become much less effective as you slow. But you need the airplane to really be done flying to get the most potential help from friction from the tires for directional control.

Planting it slow and straight and getting those controls full over and weight on that nosewheel leave you in the best configuration to be no lift left, a ground vehicle with a lot of surface area being pushed on by the wind and go kart tires. Landing faster just gives you more speed to lose control of what’s essentially, a really badly designed go kart trying to be blown over.

Wheeling along with lots of lift still coming from the wing and a transition time between flying machine and go kart, isn’t helping you at all. It’s reducing friction of the go kart tires and making it harder for them to do their job, not easier.

 

[Bill Watson]

Lots of good stuff in the last couple posts.

I would emphasize the convention and trike gear are different animals in these situations.

I would say *never* speed up a trike for control effectiveness except to account for gusts. Trying to drive it on at a low deck angle is not the way to go.

You can transition to a slip as soon as you turn final. If there isn’t enough rudder for runway alignment it will be obvious and you will just maintain some crab angle in addition to a full deflection rudder slip. It’s a great way to get proficient with slips. The almost always present wind gradient will mean that your crab angle will decrease as you descend all the way into the flare. If you are lucky the crosswind will decrease to the point where alignment is reached with full rudder.

You really can drive a conventional gear plane on with a wheelie. It requires a push on the stick at touchdown and pressure to keep it there with extra speed. The wheels aren’t really helping you until they are both down when you can lean on the downwind brake. Main thing is to keep things moving straight but not necessarily on the centerline. A wide runway really gives you some options. But the gear is fundamentally unstable on the ground and is always wanting to swap ends.

You never want to drive a trike on. You never want to push the stick, only release back pressure. But you can touch down a bit crooked because the gear is fundamentally stable. It wants to go straight. It tends to correct mistakes if you give a chance. Driving to nose wheel on is just going to hurt the plane or possible you.


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[Bill Watson]

Of course there differences of opinion regarding crosswind techniques. I call it the KISS technique, after all mechanics need work as well.

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