Less than full flaps w/x-winds / gusts

[fourierman]

Anyone have a reference (AC, etc) from a FAA publication (or other reliable src) that suggests use of less than full flaps for crosswind landings?

I thought the AFH might have something , but don't have the book yet so can't look it up.

Also, I'd be curious to hear various resaons why you don't want to use full
flaps when landing with a crosswind.

One instructor I flew with said to use full flaps because you don't wnat to stay in the flare/ground effect any longer than necessary. Full flaps->lower gs -> less floating, etc.

I brought up the fact that control (aileron, etc) authority/responsiveness is probably less than optimal with full flaps.

Another instructor says camber of wing is changed with flaps and greater surface area (?) leads to more of a disturbance from gusts, etc..

[MidlifeFlyer]

I don't think you'll find anything in the AFH on it. I'm pretty sure this is one of those personal preference things, with purists taking one of the two sides you mentioned making precisely the arguments you mentioned. You may find something in some aircraft manuals with recommendations against extended slips with full flaps or recommending the minimum flaps for the length of runway.

[desertdog71]

Well, I am far from qualified to answer but, My instructor has suggested that a 20 degree flap is about the most you want on gusty crosswind landings, this is due to the fact that a gust can toss you around easier with the added lift from having the flaps extended. Flying in Kansas, you just have to deal with gusty crosswinds as part of life. But it probably is just a preference thing.

[Baronman]

When using partial flaps in a stong crosswind you would probably want to add at least 5 kts to your approach speed to account for the slightly higher stall speed.

Approaching at a higher speed will give you slightly better rudder authority. Think how mushy your ailerons feel during slow flight, and how unresponsive they feel...Well same concept with your rudder, if you want an effective rudder to straighten the nose to "uncrab" during touchdown it helps if more airflow is going over it.

Additionally the ailerons/elevator will be more effective during the approach at a slightly higher speed....

I personally used the second flap setting in the Pipers as standard for landing, the full flaps seemed to make the plane a real dog, especially in the Seneca. Of course in a short field scenario full would be the way to go.

[B767Driver]

The Airplane Flying Handbook, pg. 8-17, states that, "...to maintain good control, the approach in turbulent air with gusty crosswinds may require the use of partial wing flaps..."

Single Engine Piper manuals recommend partial flaps in gusty conditions as well.

As stated above...be sure to add some speed...a rule of thumb is to divide the gusts by 2 and add it to the normal approach speed...and to give yourself some extra runway as well...you are probably going to float.

I agree with both philosophies...partial flaps and full flaps. Personally, I like full flaps, like the instructor above, because I don't like going into the flare with excessive speed...it makes more difficult the flare, introduces floating, is harder on the brakes and tires, and accident history shows that the higher the speed on landing...the greater the opportunity for some type of runway excursion. But it will increase control effectiveness which should be given consideration.

[riot shields]

actually, i read this post last night and today i had gotten into a situation where this came into play.
my student and i were doing some short field landings today over at an airport thats 2,000 x 30 feet, pretty good short field airport. his approach was good, real good actually. there was a 30 degree crosswind at 20 knots maybe, but everything went fine until the flare, the problem was, he didnt flare. we bounced up, no problem, but he failed to initiate a recovery, he kinda froze. i told him, nose down, add a little power, etc, but he didnt do much of anything, he pressed the rudder pedals a little, and turned the ailerons into the wind, but there wasnt much response. i had to take over just in time to touch slightly off the side of the runway, but everything was pretty safe.
a close call, but he really got to see first hand in his training what very slow airspeeds do to a plane, regarding a very sluggish and lazy airplane with a lack of airflow over the control surfaces.

thought i might share that story.
a good learning experience...

[Champcar]

In the 172s 20 degrees is what I always use in x-wind conditions, actually I never use 30 degrees anymore on calm days...just too much drag for me.

[moxiepilot]

Originally Posted by Champcar

In the 172s 20 degrees is what I always use in x-wind conditions, actually I never use 30 degrees anymore on calm days...just too much drag for me.

Why wouldn't you use 30 degrees on a calm day? Doesn't the POH (the manufacturer) recommend that?

The way I see it is to teach the procedure set by the people who built the airplane, then as conditions warrent deviate from that set procedure. If you continue on to CFI or into the airlines/corporate what will you do reagarding the use of flaps?

[Champcar]

Originally Posted by moxiepilot

Why wouldn't you use 30 degrees on a calm day? Doesn't the POH (the manufacturer) recommend that?

The way I see it is to teach the procedure set by the people who built the airplane, then as conditions warrent deviate from that set procedure. If you continue on to CFI or into the airlines/corporate what will you do reagarding the use of flaps?

Its just how I land. If im landing on a runway 4000 feet of more i like to use 20 degrees with some power..makes for a smooth landing. Im not a big fan of "diving" for the runway to a full stall like i was taught. Just because 30 is recomended doesnt mean i have to fly that way.

[jrh]

Originally Posted by Champcar

Its just how I land. If im landing on a runway 4000 feet of more i like to use 20 degrees with some power..makes for a smooth landing. Im not a big fan of "diving" for the runway to a full stall like i was taught. Just because 30 is recomended doesnt mean i have to fly that way.

It's funny you should say this because I've realized it's a really common phenomena in lower time pilots. I remember doing it myself. When I had about 140 hours I went flying with a guy that had four times as much experience as me and we did some touch and goes. He looked at me funny for not using full flaps. "Full flaps, every time, is the way real pilots do it," was sort of his attitude. For whatever reason, I found it easier to land with partial flaps and I didn't see what the big deal was.

Now that I have more experience I feel naked without using full flaps. I didn't work hard to increase my abilities, it just happened with time. I have a better feel for the plane now. I don't know how else to describe it. The same thing will probably happen to you.

[Ralgha]

We rarely use full flaps in the Brasilia.

[LostComm]

Also, for many aircraft, flaps 20 (or less than full) is your go around configuration, and on a gusty day that's a good position to be in. Remember that a landing is simply an aborted go around!
-LC

[Champcar]

Originally Posted by LostComm

Also, for many aircraft, flaps 20 (or less than full) is your go around configuration, and on a gusty day that's a good position to be in. Remember that a landing is simply an aborted go around!
-LC

Which is another reason why i like to land at 20, if i have to go around im ready to go, 30 degrees really hurts your performance specially at high density alt ariports that im used too.

[MidlifeFlyer]

Your POH can be your friend. Here's what the Cessna 172S manual says:

==============================
Normal landing approaches can be made with power on or power off with any flap setting desired. Surface winds and air turbulence are usually the primary factors in determining the most comfortable approach speeds. Steep slips should be avoided with flap settings greater than 20 degrees due to a slight tendency for the elevator to oscillate under certain combinations of airspeed, sideslip, angle, and center of gravity loadings.
==============================

So Cessna says the choice is mine although I should consider using less than full in a substantial crosswind if my technique is going to be closer to the "slip all the way" than to the "crab and kick" end of the spectrum.

Good enough for me when flying a 172.

[ColMustard]

Any pilot worth his/her salt ought to be able to make safe landings using any set of flaps, depending on the situation. We all know flaps help the aircraft approach at slower speeds and steeper descent angles, but that may not always be necessary. There are shallower approaches for soft touchdowns and long rollouts, the possibility that the flap motor went TU, gusty conditions, severe headwind, tailwind landing, etc.

I teach my students to understand what the flaps do during the approach (adds both lift and drag). I try to emphasize that full flaps won't always be necessary, with the possibility they will get comfortable with the "routine" of landing that plane (and we all know that no two landings are exactly alike).

No black and white answer on this one, but if the pilot should want an SOP to "hold on to", then the POH is a great start.

-ColM

[subpilot]

I was doing touch and go's once in a C172 using full flaps and when we went to raise the flaps...nothing happened. We aborted the takeoff but that would have sucked if we had actually done a go-around or did not notice that the flaps did not raise. I love pipers because of the manual flap lever.