How to kill yourself by listening to Bob Gardner's advice

[Chapster]

Check out the topic on landing without flaps...My God!!...its' full of stars. NEVER DO WHAT BOB DOES is the moral of the story!!!!!

[SeaAir]

As I read Bob's reply in the "landing without flaps" thread, he appears to be describing the proper technique to use for light airplanes. (If you are flying a commercial jet with reversing thrusters, then the rules are a little different.) Whether or not you use flaps (which is dependent on personal choice, wind conditions, type of airplane, etc.), you should retract the flaps as soon as the wheels are on the ground to improve braking efficiency and to allow for a go-around if need be. Leaving them down until you leave the runway is usually ok, but I would rather pull them up sooner.

[1739T]

Chapster, A little rough on Bob I should think. I routinely raise flaps on windy days after touch down to improve braking efficency or on a soft rough field where I don't want to dangle anything that doesn't need to be dangled.

Also when taking off from a short soft field I'll lower 10 degrees of flaps as I rotate. I don't put 'em out for the take off roll because don't need the drag. Now, I spent a couple hours with an instructor before I tried this and simulated on a hard surface, long runway but the point is the use of flaps up or down is very different for different aircraft and circumstances.

In most cases you should never touch the flaps until you are clear of the runway. This kind of action on a commercial checkride will yield a pink slip. One of the reasons for this, is that a number of pilots have mistakenly put the gear up while on rollout. For some aircraft this may result in a gear up landing. If you are in need of more effective braking, try a longer runway. In other words, if you must put the flaps up during rollout to ensure that you stop before the end of the runway, then you are landing too long or you are landing on a runway that is much too short. There is absolutely no operational need to put the flaps up during rollout.

I realize that some of the POHs provide the pilot with the option of dumping flaps on rollout for a short field landing (the POH for my Turbo Arrow indicates this). At the risk of contradicting myself, the POH should be followed and making up steps not described in the POH during landing or takeoff should be avoided.

Another reason to avoid changes to the configuration is staying focused on the task at hand. During takeoff the last thing you should be doing is reaching over/down to change the flap configuration. Similarly on landing, you should be focused on the runway and maintaining the centerline. Taking your eyes and focus off of the runway is dangerous at this point.

[SeaAir]

It just goes to show you that there is more than one way to skin a cat.

Actually, I just took my commercial check ride a couple of months ago and the examiner didn't say anything about my raising the flaps on landing. I do admit that when I do it with younger instructors they tend to raise their eyebrows a little. Maybe it's a new thing.

Your comment on the POH for the Turbo Arrow sent me looking the section in the POH for my Turbo Arrow. In the normal procedures section for approach and landing it says, "Braking is most effective when flaps are raised and back pressure is applied to the control wheel, putting most of the aircraft weight on the main wheels." Of course as you say, if you are landing on a 10,000 foot runway, who cares.

SeaAir,

I've got about a dozen POHs and almost every one (I've got mostly Piper POHs) "suggests" dumping flaps as an option to enhance braking action. On a calm day try doing some short field landing practice with and without a flap configuration change. I found that the difference is relatively minor. Instead focus on other elements like maintaining proper airspeed. For short fields, it is less important how much runway you have in front of you as how much you left behind you. So, don't use the "effective braking" assistance as a replacement to a poor approach and landing.

Actually, my examiner is a 20,000 hour pilot and she made me well aware of the requirement not to dump the flaps. However, I've never understood how an examiner could fail you for following the procedures (even those that are optional) listed in the POH. I think her main point is simply, "use a longer runway if you have to go to that extreme."



[This message has been edited by scottd (edited 04-04-2002).]

[summitgolfer]

Here's another perspective. I live in Alaska. In the last two years I have landed on pavement once. Whether you're landing on a sandbar, tundra, or a short lake, there are times that flap retraction at touch-down is necessary. Does this mean I shouldn't land there? I don't think that's the case. I think flaps are a tool to be used to improve the performance of an airplane. All pilots should strive for mastery of the plane they are flying. If specific techniques improve the capability of that plane, why wouldn't you use them. As for the POH, take a look at the difference between a '53 Cessna 180 POH and a '81 180 POH. These airplanes are essentially the same. The POH's are very different. The content of late-model POH's has more to do with manufacturer liability than aircraft capability. Operational procedures are guidelines, not limitations. Limitations are listed clearly in their own chapter.

[skid]

I think this discusion illustrates several things. Many people want hard and fast answers when its not quite that simple. The biggest variable in aircraft performance is pilot capabilities. What can safely be done by a skilled capable pilot with a lot of time in type is certainly not what you would teach to everyone transitioning to a new airplane. Another problem is that while many people eventually develop the whole abstract art of stick and rudder skills, most just use a step 1,2,3 approach and never really observe what is going on. These people seem to focus on getting a rating rather than perfecting the mechanics of the requirements for the rating. These people also seem to have a problem knowing whom to trust for advice. And as mentioned earlier, product liability has obscured a lot of things to protect manufacturers from idiots that aren't going to get the full grasp of it anyway. Just keep humbly observing and questioning things and eventually the right answer will float to the surface.
By the way, I'm surprised nobody mentioned gusty crosswinds. Dumping the flaps right after touchdown greatly lessens the chance of a gust making you airborne again. In a stiff crosswind you may already be using a great deal of rudder to keep pointed down the runway and you don't want to balloon up, get slow and come down drifting sidways out of rudder. The other thing is that on some tailwheel airplanes full flaps can slightly affect rudder effectiveness. Obviously, if you're working pretty hard to land the airplane, these things are secondary to doing a good job in the first place. Very few short answers in aviation.

[ScottG]

On the big dump flaps on landing debate...

How many of you/us/me included, have actually figured out the difference for our particular planes?

That is... when you land, some POHs or lore say that putting the flap weight back up over the wheels may help. Leaving aside the accidentally gear up issue for a moment, is this really true?

When you land, even after ground affect dissipates, you still have forward speed... you are still generating lift, albeit not enough to be airborne. As such, aren't the flaps still producing some relatively high amounts of induced drag?

Lets forget aerodynamic theory even for a moment. How about some tests?

I'm kind of curious about this. I think next time I go to my favorite long runway for some percision practice with the ILS markings I'll try and test this for the Archer II I fly.

Because in a way... this is sort of a dumb argument. Non unimportant mind you, but silly in a way. Why? Because why argue about something that can be safely tested?

Probably different for different planes, and maybe different wind conditions.

Scott

[Frodo]

As far as stopping quicker, raising the flaps will put more weight on the tires, but this only helps you stop if you are braking hard enough that the lighter weight would allow the tires to lock up. Thats a lot of brake action on a dry surface.

If you are on a slippery surface I highly recomend aero braking, in which case you want the flaps down and then hold the nose up as long as possible.

In gusty or cross wind situations, it is true that flaps can cause directional problems and it is useful to get rid of them on roll out. However, they also cause problems on short final in these conditions and I will land with reduced or no flaps on days like this.