There’s normal, and then there’s normal. Which is to say that while much of aviation relies on routine procedures and aircraft configurations, among other things, there are exceptions to most norms. For example, the FAA long ago declared a “normal” landing to be one with an airplane’s wing flaps, if any, fully deployed. That’s not the same as saying we always must extend full flaps before landing, no matter what. Like in a stiff, gusty crosswind, for example, whose presence means the landing is not “normal.”
Instead, airplane design and the wind conditions themselves are factors that can strongly argue in favor of partial- or no-flap crosswind landings. The runway we’re trying to use is a big part of the decision also, since good technique for a gusty crosswind is to add half of the gust value to the final approach speed, often designated VREF. Greater speed on approach and landing means a lengthier runway requirement. Another consideration is whether going around is a likely outcome of the approach, since many airplanes don’t climb well with full or partial flaps deployed.
Flaps, of course, come in all shapes, sizes and degrees of effectiveness. The barn doors on some 100-series Cessnas, especially when deployed to 40 degrees, is in stark contrast to, say, a Cessna 310’s split flaps. And the airplane’s basic design itself figures into the flaps deployment question when dealing with a crosswind—other things being equal, a low-wing airplane typically is more controllable in a gusty crosswind. And controllability during the upcoming landing is of greater importance than normal.
How well the airplane handles crosswinds in the first place also bears on the speed we want to use, and has a lot to do with whether to use flaps. Aileron and rudder effectiveness at low landing speeds is the critical factor and, if you routinely run out of rudder in a steady, non-gusty crosswind, for example, you might want to add a couple of knots, at least until close to the runway. If the airplane has a tendency to float with full flaps, using a partial setting can be the cure.
Airplane weight also can be important. If it’s just you aboard at the end of a long cross-country, you’re going to be light. All things being equal, a heavier airplane is more resistant to gusts and crosswinds, since it take more force to displace it. How the airplane responds to a gust at your weight can mean you want to use a higher speed, and go-around considerations may mean a partial-flap landing is best.
There can be a delicate balance between runway length and width, and how much gusty crosswind we can tolerate. As discussed, we’re typically taught to use a slightly higher approach speed in these conditions. But that extra speed has to be dissipated somehow before we can come to a stop on the runway. We typically do that in the flare on a calm day, but such a technique isn’t always the best when wind direction and speed are constantly changing.
And the crosswind itself means we may not be able to stay as close to the centerline as we would like, especially in the flare before touching down, after which we can use the landing gear to help establish and maintain directional control. More pavement in the lateral dimension is an insurance policy in such conditions.
How do the runway’s dimensions relate to flap use? If we’re trying to get into a short field with a gusty cross, we’re probably a bit faster than normal, having added half the gust value to our approach speed. To minimize the runway length requirement, we might want to add flaps. And we might not, which makes a relatively short, narrow runway more of a concern than if we were at NASA’s Shuttle Landing Facility.
No matter how likely our chances of completing the landing, stuff happens and we may need to go around. Some airplanes, perhaps with less-effective flaps, respond well when full power is applied for a go-around in the full-flap configuration. Some don’t, and many will respond with a strong tendency to pitch up regardless. That pitch-up tendency coupled with less-than-stellar acceleration with flaps deployed may mean that leaving them fully or partially stowed is the best choice.
If deploying full flaps is your considered choice for this landing, you may want to make the go-around decision sooner than normal, and at a higher altitude above the runway. Regardless of flap effectiveness, sluggish acceleration for the go-around may itself be a major concern, along with terrain or obstacle clearance.
There’s also workload to consider, since few personal airplanes climb all that well with flaps extended. Retracting fully deployed flaps on a go-around is best done in stages, a “notch” at a time. Until the flaps are fully stowed, along with the retractable landing gear if so equipped, climb performance will suffer. Depending on the systems, that can take a while, during which you’re in the precarious position of being relatively slow, just above the runway and dealing with unpredictable winds, while managing all the systems. It can be a busy time.
Practice Makes Perfect
The bottom line in this discussion of whether to use flaps and, if so, how much, really comes down to the conditions you’re experiencing. If you’re trying to get into a relatively short field, full flaps might make sense. Same with a soft field. If you’re landing at Class B International, with its long, wide runways and a controller asking you to keep your speed up, not so much. And if all this is new to you, and you have no idea how to decide whether and how much wing flap to use, go get some practice.
It would be nice to do it with an instructor, but that’s not as critical as choosing the right day and the right environment. Try a runway with a steady-state crosswind first, and make multiple landings/approaches with different flap settings. Find one that seems to work best for those conditions. Include a go-around in the mix and decide how busy you want to be.
Next, pick a gustier day and do it all over again. It would be ideal to be able to vary the airplane’s weight, but if you fly enough practice approaches and landings, you’ll burn off some fuel and maybe learn more about how a gust can push you around in the flare. It’s all about maintaining control in a gusty crosswind and getting the airplane on the ground in one piece when it counts. It would be nice if you’d done it before.
This article originally appeared in the June 2021 issue of Aviation Safety magazine.
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This is a great article, but it misses one little detail… roll yaw coupling. Adding rudder will always create a bit of roll, but when it creates a lot of roll it makes crosswinds (especially gusty crosswinds) hard to handle.
The amount of roll yaw coupling is not necessarily the same for all flap positions. In my airplane, roll yaw coupling actually does down as flaps are extended. So, it’s easier to land in gusty crosswinds with more flaps rather than less.
A great place to start is by measuring your phi / beta ratio for various airspeeds and flap settings.
Another useful trick is to land slightly across the runway. Landing on the centerline is not a must. In a crosswind (gusty or not) landing diagonally reduces the crosswind component. Trigonometry rules. Remember that at 30 degrees off the runway the crosswind component is half the wind’s velocity. In a lightly loaded aircraft or one with a low crosswind threshold, a few degrees into the wind makes for a meaningful reduction in crosswind component.
I agree with Serena Ryan, but lacked the courage to say it. Unless I’m at a particularly narrow runway I might aim at the corner, rather than the centerline. (Indeed, with our old 150 I’d land on the grass between the landing lights and runway.)
Further, the Impossible Turn need not be right back on the runway I left, but a crossing runway, taxiway, random dirt. I’m of the school that suggests that if anything happens to the engine in flight my passengers and my safety becomes my big problem and the airplane becomes the insurance companies.
In defense of Cessna 100 series barn door flaps, they come up nicely and the airplanes are all easy peasy to fly, except the 190 which does not have good flaps. 40 degree flaps increase drag and very little lift so that comes off fast. Then things are more relaxed, well usually, or at least sometimes.
Good article. After 23 years of ownership and 1700+ PIC hours in my 1986 Maule MX-7-180 taildragger in all kinds of landing conditions, I use one notch (24 degrees) of flaps when landing in a gusty crosswind. Retracting the flaps completely makes for a much flatter, higher speed landing that causes the airplane to float. That’s not a good thing because as the airspeed decays before touchdown, the crosswind exerts more sideways force. Touching down with any sideways motion in a taildragger is an invitation to ground loop. The stall speed is higher with no flaps and that’s not a desirable thing either as airspeed decays before touchdown.
In a gusty crosswind, the idea in a taildragger is to get all three wheels on the ground as soon as possible for more control. Applying more than one notch of flaps increases lift significantly as well as drag. The additional lift allows the crosswind to exert more force on the wings – especially the upwind wing. That can lift the upwind wing and push the airplane sideways or spin it around on the downwind wheel.
The bottom line is to know the airplane and gain experience in all its different configurations and landing conditions.
if you are going to do a wing down landing in a Cessna, be aware that slips with flaps can be an issue; read the POH.
Flying about a thousand flights in a 180, I found that the effect is an easily managed pitchdown while using a lot of slip with full flaps.
The answer is to reduce the slip, or reduce the flaps, which are affecting the flow over the stabilizer.
Know your aircraft; know your POH!
I did my solo flight years ago in a Piper Warrior on an overcast day with a direct right crosswind at 12 gusting to 18+ knots. The airport was virtually empty except for my instructor and I. I thought he might be a little insane when he got out of the plane after three trips around the pattern. And every time ATC called out the winds on the next three landings I thought I would never be as brave as my instructor to risk letting a student solo in those winds!
In his defense (and mine), I had some challenges getting my medical and was at over 30 hours at that point – some of you may have had a PPL by then.
Full flaps worked for me that day, and I generally still end up using them in direct crosswinds. I am more inclined to reduce flaps if the gust direction is more in-line with the runway heading.