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X wind limitations side slip or crab style approaches

Posted: Sun Oct 29, 2006 9:17 am
by Wasn't Me
It's Sunday and it's blowing in Mississauga. Thought I'd get some feed back as to what you consider useing for a X wind approach. Which do you prefer sideslip or crab on final.

Posted: Sun Oct 29, 2006 10:31 am
by Spokes
I teach my students to slip. It seems to me to be a bit easier on the equipment. PPL students who attempt to crab seem to always bounce hard and not straight ahead. Besides in my mind nothing looks more elegant than a nicely flown x-wind landing using a slip.

Posted: Sun Oct 29, 2006 10:34 am
by Pugster
Both.

Crab until just prior to the flare, then straighten the nose out and sideslip for the landing.

Posted: Sun Oct 29, 2006 11:00 am
by . ._
If the runway is wide, I just yank the power and stuff the nose. @#$! it.

-istp :smt066

Posted: Sun Oct 29, 2006 11:35 am
by C-GPFG
Pugster wrote: Crab until just prior to the flare, then straighten the nose out and sideslip for the landing.
That's how I prefer and teach. When slipping, I've found students have a harder time maintaining the required bank down a bumpy crosswind approach.

Posted: Sun Oct 29, 2006 2:37 pm
by Icebound
C-GPFG wrote:
Pugster wrote: Crab until just prior to the flare, then straighten the nose out and sideslip for the landing.

That's how I prefer and teach. When slipping, I've found students have a harder time maintaining the required bank down a bumpy crosswind approach.
From a student's perspective:

I was taught to slip the approach, so I use it. I have been afraid to try a crab-to-last-minute-slip, because it seems to me that it would be too easy to put in too much or too little rudder (and aileron), having put in none all the way down.

In the slip-all-the-way, I have a whole approach to determine how much rudder I need. And it is true that I may not maintain the required bank all the way down, but I only need to have the correct bank once, at the very end.... and I have a whole approach to have found out how much rudder and aileron I am probably going to need to get it close.

Now I have no doubt that a successfully-executed crab-to-last-minute-straighten probably demonstrates more skill than a successfully-executed slip-all-the-way.

But it would be interesting which has the higher damage-to-landings ratio, especially when executed by us low-timers.


...

Posted: Sun Oct 29, 2006 3:46 pm
by Pugster
Icebound;

I hear ya. Learning the sideslip (say from 1/2 mile final or so) during the initial stages of training is probably the best way to figure out how much rudder you're going to need.

Once you get a bit more proficient, hold the crab on final longer and longer - it's actually very easy to gauge how much rudder you need - all you do is push on the pedal until the nose becomes aligned with the runway. From here just nail down the amount of aileron you need to counter drift, and voila - crosswind landing.

As far as aircraft damage goes, I'm not sure, but I really wouldn't be too worried about it. If it's so windy you are at your own limit, bring an instructor. If you're on your own, just remember that your best out if you feel you're getting down low and things aren't looking good is to go around.

Posted: Sun Oct 29, 2006 4:02 pm
by C-GPFG
Icebound wrote:
C-GPFG wrote:
Pugster wrote: Crab until just prior to the flare, then straighten the nose out and sideslip for the landing.

That's how I prefer and teach. When slipping, I've found students have a harder time maintaining the required bank down a bumpy crosswind approach.
From a student's perspective:

I was taught to slip the approach, so I use it. I have been afraid to try a crab-to-last-minute-slip, because it seems to me that it would be too easy to put in too much or too little rudder (and aileron), having put in none all the way down.

In the slip-all-the-way, I have a whole approach to determine how much rudder I need. And it is true that I may not maintain the required bank all the way down, but I only need to have the correct bank once, at the very end.... and I have a whole approach to have found out how much rudder and aileron I am probably going to need to get it close.
Not saying that's a wrong technique, but the winds can be very different at 500' vs. the flare height. You really don't know how much bank you'll need until you're in the flare anyway. I find it easier to adjust the crab on the way in than to adjust the slip. In the flare, I point the nose down the runway with my feet and dip the wing a little at the same time.

Posted: Sun Oct 29, 2006 4:13 pm
by Wasn't Me
I have found that in strong crosswinds it's better to crab than to slip and then coordinate the slip close to the ground. The crab gives me better directional control than the slip in strong winds and I'm not as tired landing the plane.

Posted: Sun Oct 29, 2006 5:39 pm
by Hedley
Generally, the more experience a pilot has, the lower the height at which he will transition from the crab to the slip, to alighn the aircraft with the runway. I really doubt that you will find a guy with 5,000 or 10,000 hours who will sideslip all the way down final. It's good exercise for a low-timer, though, who has to learn how to do this with precision.

I shouldn't mention this, but .... you can actually land a light nosewheel aircraft in the crab, and it will quite safely straighten itself out - the center of mass ahead of the main gear will see to that. The tires will howl in complaint, as will the instructor in the right seat, but ...

With winter coming on, it is worthwhile mentioning that if you have to land in a crosswind on a 100% ice-covered runway, landing in a crab is actually a pretty good way to do it. You can do the slip at touchdown if you want, but the aircraft is going to weathervane into the crosswind on the rollout anyways, so it's actually wasted effort.

The worst surface to land on in a crosswind is probably 50% glare ice and 50% bare pavement - during the rollout the aircraft will alternately weathervane into a crab on the ice, then straighten out on the bare pavement, etc.

Suggestion: crab on final, and just before touchdown, kick it straight and touch down in a slip only on the upwind main. Aileron full over, to keep the upwind wing down, and produce maximum adverse yaw on the downwind wing to help oppose the weathervaning effect of the crosswind.

Posted: Sun Oct 29, 2006 5:55 pm
by Lurch
During my PPL I was tought to crab and then slip in the flare and I never really got the hang of side slipping. Once I was told to slip all the way in I got the hang off side slipping and was able to go back top the crab/slip method.

When I instruct students I teach them to side slip all the way down final. This way they get lots of practice side slipping. Yes the wind is differant at 500' and ground level but when is wind really constant? It is ever changing in speed and direction so the student needs to be good with his hands and feet to maintain centerline.

When the student gets good at side slipping then teach them to crab until the flare and then initiate the slip and flare at the same time. A little more piloting skill required but should we expect anything less?

Lurch

Posted: Sun Oct 29, 2006 6:29 pm
by JohnnyHotRocks
Depending on the aircraft, sidesliping all the way down will cause you to scrape a wingtip in certain crosswind conditions...maybe it's better to teach "crab until you are in the flare" so the students are better prepared for more advanced aircraft later in their careers....

Just a thought...

Posted: Sun Oct 29, 2006 8:59 pm
by gr8gazu
Crab is the preferred technique for sweptwing aircraft. Ideally, you should crab all the way into the flare when you kick it straight with rudder and use only enough aileron to keep the wings level. At that point, you should be touching down. I have used this technique in x-winds up to 50 kts and while you will not have enough rudder authority to completely align with the runway, you greatly reduce the risk of scraping a tip.

Posted: Sun Oct 29, 2006 9:44 pm
by Pugster
JohnnyHotRocks wrote:maybe it's better to teach "crab until you are in the flare" so the students are better prepared for more advanced aircraft later in their careers....
Agreed. I'll add to this that because crosswind landings take a fair amount (not really that much...) of coordination on the students part they're a great way to develop handling skills. One of my "mentors" instructing (actually a TC guy...go figure!) suggested that one of the best things I could do for my students was get them out flying in crosswinds when we got them (we didn't get many at all). It's especially important when you're training up a PPL as it may be the only day you get (depending on location), and it may be the only time they receive dual training in a real crosswind.

So considering that this thread has actually been pretty civil and productive (nice change, eh?), I'll continue with some advice for new instructors. If you've got a good crosswind going (especially a steady one where they don't normally exist), get on the phone and start calling your students. It's one of those lessons that can't really be taught unless conditions are right - and also one of the lessons that has a good chance of keeping an airplane from getting bent.

Posted: Sun Oct 29, 2006 10:25 pm
by looproll
you can actually land a light nosewheel aircraft in the crab, and it will quite safely straighten itself out -
apparently you can do this with a 12 500lb twin as well. I cringe, I cringe!

Posted: Sun Oct 29, 2006 10:51 pm
by Airtids
Teach the slip, graduate to the crab. Easy to difficult, simple to complex.

Posted: Mon Oct 30, 2006 12:09 am
by Pugster
looproll wrote:
you can actually land a light nosewheel aircraft in the crab, and it will quite safely straighten itself out -
apparently you can do this with a 12 500lb twin as well. I cringe, I cringe!
The funny part of this is that I know exactly who (a Capt) and what (BE20!) you are referring to! If you haven't figured it out yet - drop me a PM.

Cheers...

Posted: Mon Oct 30, 2006 5:33 am
by Sure Shot
Airtids wrote:Teach the slip, graduate to the crab. Easy to difficult, simple to complex.
slipping is easier than crabbing? crabbing is straight and level while slipping is cross-controlling. so its better to just crab. plus if you have a bunch of passengers on board theyll wonder why the hell the plane is coming in wing low, crabbing is better for them to.

Posted: Mon Oct 30, 2006 9:35 am
by KAG
I was taught, and I taught the crab technique, then straighten out with rudder and dip the wing to keep straight.
For newer pilots try crabbing until over the approach lights (or clearway) then straighten it and dip the wing, for more experienced pilots keep the crab in until the flair.

I use this for a few reasons:
It’s much more comfortable for those in the back.

I’m lazy, let the plane do the work for you – it’s much harder to slip it in from a mile back then it is to crab.

When you move onto bigger machines, the preferred method is crabbing, so why not learn it right the first time?

You do not have to hold the crab in until the flair, when you decide to slip is up to your comfort level, the plane you’re flying, and your experience level.
Believe me, this is a much easier, comfortable, way of landing in a Xwind, and the plane can handle a much stronger wind.

Cheers.

Posted: Mon Oct 30, 2006 11:26 am
by Lurch
It's funny, for a change everybody is arguing the same technique.

Posted: Mon Oct 30, 2006 11:26 am
by Doc
Max power on the lee....idle power to windward...kick the prick straight on landing...works for me!

Posted: Mon Oct 30, 2006 1:13 pm
by co-joe
I used to have the student not only fly the entire final segment in the slip, but would get them to fly the length of the runway in ground effect holding exactly centreline in the slip. This was purely a coordination exercise and once they had it mastered, I'd let them do whatever worked for them.

Most often crab until the flare, then power to idle, and side slip until the touchdown.

As was stated earlier, the winds at 500' are often quite different than in the flare, so flying the slip all the way is just an exercise to keep them monitoring airspeed (noting asi errors associated with slipping) and working to hold centreline. More aileron more rudder, less, less... etc.

Posted: Mon Oct 30, 2006 2:34 pm
by Pugster
co-joe wrote:(noting asi errors associated with slipping)
Why would you have ASI errors during a properly executed sideslip? Are you confusing with a forward slip? Or am I just missing something here...

Posted: Mon Oct 30, 2006 5:44 pm
by co-joe
Hmm? I thought there were errors with a side slip as well. Anybody wanna go try it out and let me know. It's been a few years.

Posted: Mon Oct 30, 2006 6:33 pm
by sakism
Shouldn't have ASI errors in the side-slip. The longitudinal axis of the aircraft is aligned with the direction of flight, therefore air into the pitot tube should be as normal.

Might show errors when entering slip until controls are set, but then should be none.