Just a survey...

[jrh]

Myth 1= increase your airspeed
Myth 2= decrease your flaps

I agree that increasing airspeed is, indeed, a myth.

I believe there is truth to decreasing flaps though. I don't really have a good scientific answer to explain the aerodynamics behind it, but I know from personal experience that decreasing flaps helps with maintaining directional control.

I've flown in crosswinds strong enough that I "ran out of rudder" when using full flaps and couldn't track the centerline in a slip. After approaching with a reduced flap setting I had enough rudder authority to keep the nose going straight ahead.

That is why I say flaps don't have to be reduced when landing in a crosswind, but do whatever it takes to get the job done. If that means reducing flaps, that is fine.

 

[MidlifeFlyer]

but the logic behind the x-wind increasing of speed might be that since the airplane is going faster, less of its vector is being taken up by the crosswind. For example, an airplane going 100 kts with a 10 kt crosswind is going to need to crab more than an airplane going 200 kts (source: geometry).

You lost me. I understand the geometry but I don't understand why it follows that you'd want to fly faster.

 

[Chris_Ford]

You lost me. I understand the geometry but I don't understand why it follows that you'd want to fly faster.

Less horizontal movement, easier to stay lined up with the runway? I don't teach it that way, but I can see the rationale behind explaining it that way..

 

[PhotoPilot]

Here's my understanding of why some pilots chose to land with extra speed and a lower flap setting:

1. It depends on the plane. If you're flying something that runs out of rudder authority rather quickly (i.e., you're trying to slip to correct for a crosswind on touchdown but the rudder is fully deflected and you're still not holding the centerline), an increase in airspeed will increase the effectiveness of the control surface. An extra 5 or 10 knots might give you the extra rudder authority you need to make a safe landing. In gusty headwinds, the reason for adding 1/2 the gust factor is completely different.

2. That extra 5 or 10 knots will also increase lift, which is where the reduction in flaps comes from. Reduced flaps equals reduced lift, allowing the plane to touch down while maintaining enough airspeed to accomplish the goal of point 1. It has nothing to do with reducing surface area so the crosswind has less to 'grab'.

3. Again, it depends on the airplane. In what I'm flying now, there's no reason to reduce flaps for any landing, as there's plenty of rudder authority. Because of that, points 1 and 2 are null and void.

The level of 'myth' varies with the airplane you happen to be flying.

 

[flyn_ace_99]

ok... just so we understand, we are not talking about gusts or headwinds... the question was about crosswinds. Steady crosswinds

increasing airspeed to "maintain control" doesn't matter in a Steady Crosswind, the amount of wind hasn't changed from a normal landing, just the direction it is coming from has changed... hense the use of the crab/winglow methods.

Decreasing flaps increases your approach speed and the effects of the wing area affected by the xwind is really marginal, and flaps have little to no effect on rudder control, elevator control(due to downwash on it), yes, but not rudder control. What is giving you the increased rudder control is the higher approach speed you must fly at a lesser flap deflection. Chances are, if you have run out of rudder control, you should probably find another runway anyway.

The increase in airspeed adversely effects control once the A/C enters groundn effect. When you are in ground effect, you recieve a 24% reduction in drag, with the increase in airspeed, you now have an increase in lift well above normal causing accessive float once you enter ground effect. The increase in airspeed also creates a longer ground roll making it tougher for the A/C to get to a speed at which it will stay on the ground.

All in all, if you read through the Jepp Private Pilot Maneuvers, Private Pilot PTS, Airplane Flying Handbooks, and MOST POHs, you will find that none of them talk about increasing airspeed for anything other than gusts and they also say nothing about reduced flap extentions.

Overall, in a Steady crosswind, you want to keep the approach as normal as possible with the exception of the crab or winglow to maintain centerline. This help to maintain the steady approach concept and you will find makes it a lot easier. Always follow what it says in the POH, the manufacturers know what they are talking about.

This is all something that I have learned just recently and haven't been able to find proof, in writting other wise. My instructor has been instructing for 30 years and his methods have improved my landings substantially. Im really excited to be learning from him and am excited to become a CFI that is worth more than just the little plastic card in my wallet.

Hey, I guess this is kindof an announcement now... I just recently started flying again, after a year long break while I was trying to figure out what to do (quit flying or keep fighting). I came accross this flight instructor/ commercial/ millitary/air racing pilot who chose to mentor me back into flying. I started my CFI school all over again (even though I already have my certificates) with the goal of making me not only a good flight instructor, but a competant airman (woman whatever). Anyway, the hard work I did for 6 months on the ground really showed themselves in the A/C when I went up on my first flight in a year and was nailing landings I couldn't previously do. I have progressed by leaps and bounds and am much happier about what I'm doing. Not to mention much more excited about flying - something I hadn't felt till now.

Anyway, the whole point of me doing this survey was to see how wide spread all this information was and to see if anyone could proove my instructor wrong and provide the proof. I tried, I couldn't prove it. (he has a masters in aerodynamics, so he is really good at this stuff).

I appreciate everybody's participation and encourage you to look into stuff like this and even if you don't agree with me, look into it and proove yourself right! Where did you hear about "increase airspeed, decrease flaps"? Was it from your instructor? where did they here it? Can you find it in a book? As instructors, it's our responsibility to give our student's the best instruction we can, for me, that includes redoing my CFI course and going through one 50 times tougher than what I had originally done.

-Marilyn

 

[desertdog71]

From a low time student perspective, I have found that Crab to the threshold, then winglow is much easier than slipping all the way down final. I have also found that the standard airspeed is fine, however a 10 degree reduction in Flaps makes things a bit easier to control. About 85 and 20 degrees of flaps on the 1969 C172 I fly. Most 172's have slower speeds from what I have heard though. We have another C172 that is a few years newer and the speeds are lower due to a different wing design.

 

[SteveC]

From a low time student perspective, I have found that Crab to the threshold, then winglow is much easier than slipping all the way down final. I have also found that the standard airspeed is fine, however a 10 degree reduction in Flaps makes things a bit easier to control. About 85 and 20 degrees of flaps on the 1969 C172 I fly. Most 172's have slower speeds from what I have heard though. We have another C172 that is a few years newer and the speeds are lower due to a different wing design.

Sometimes the speeds appear to be lower if the older plane's airspeed indicator is in MPH, while the newer planes are KTS. Might account for the difference you are hearing about(?).

 

[desertdog71]

Both are in MPH, the newer plane has a different wing. By newer I think its like a 1972 or something. I will have to check for sure though.