The Pilot’s Lounge #4:
Why Not Use Those Flaps?

Which group do you fall into - the flap crowd or the no-flap crowd? Do you know when it's best to use wing flaps for landing and when it's best to leave them stowed? This is one of general aviation's longest ongoing debates, especially with the lighter, smaller models in the fleet. After defusing an emotional

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The Pilots LoungeIt had been one of those busy Saturday mornings at the office. Itwas going to be nice to get out to the airport and spend a little time in the pilot’slounge readjusting my perspective on the world. I had a little time before an aerobaticstudent was scheduled and then it was going to be home for the honey-do’s. I figured itwould be pleasant to relax in the lounge, listen to and tell a few lies, check the packdates on the chutes and get ready for my student.

It didn’t exactly work out that way.

I arrived just in time for the end of it. Some prettyharsh words still hung in the air. The combatants had been pulled apart by other loungeregulars. New student Barb, who had brought her twins, Erika and Erin, out to see what shewas doing, looked on in open-mouthed astonishment.

Recognizing the protagonists, I looked over at Hack, whohad one’s arms pinned securely and said, “Flaps?”

He grimaced and said, “Yup.”

The two were walked off in separate directions and, with afew stern words on the side, told they should stay away from the lounge for a weekend.Things settled down and before long the usual discussions in the lounge flowed around mewhile I considered what had just happened.

Here in the lounge we have a microcosm of one ofaviation’s major disagreements for little airplanes. Our two friends have been arguinghammer and tongs over the use of flaps on landing. They reflect a battle I’ve listened toamong pilots throughout the time I’ve been flying and virtually everywhere I go. In fact,the FAA once stepped in and decreed that a normal landing is with full flaps. Having thegovernment make a pronouncement to the group of individualists who make up the pilotcommunity had the predictable effect of fanning the flames of disagreement.

To borrow from Winston Churchill, never have so manyargued so long and so hard over so little.

What makes the whole flap over flaps so funny is that bythe time you get away from the smaller, single engine airplanes, the argument goes away.Virtually everyone uses full flaps for landing on the bigger singles and the twins.

But, discuss landing a Cessna 150/152 or a Cherokee 140and it is Katie bar the door, there will be strong emotions and sometimes, fighting words.

The no-flap or partial-flap crowd points to a number ofOwner’s Manuals and Operating Handbooks that repeat a phrase which says something alongthe line of using the minimum flap setting for the runway length on landing. Theycorrectly point out that the pitch change from the final approach glide in the flare issmaller without flaps and so it is easier for less-experienced pilots to make a landing.It is easier to get the airplane lined up on the runway in a crosswind because of theextra airflow over the control surfaces. It is also easier to make a go-around from apartial- or no-flap approach. They say it is hard to judge the flare when descending sofast, power off, with full flaps. Besides, the partial-flap crowd points out, on manyairplanes there is only one knot difference in the stall speed between half and fullflaps.

The other side of the argument tends to be that using fullflaps results in a slower touchdown and less bouncing around in gusts because the addeddrag helps stabilize the airplane. Proponents add that the flaps are on the airplane for apurpose, not decoration, and it doesn’t matter that you come down final with lots ofairflow over the control surfaces, sooner or later you have to slow down and lose thatairflow.

So, what do we have?

It’s true, for pre-solo pilots sorting out the problem oftrying to keep all those monkeys under the bushel basket, the touchdown part of a reduced-or no-flap landing is easier to learn. A good instructor will have the student configurethe airplane for landing in a way that minimizes distractions and lets the studentconcentrate on hitting that there runway. Only after the initial skill is gained does agood instructor start teaching the more complicated landings, such as short field, softfield, wheel (for tailwheel airplanes) and crosswinds.

I’ve noticed that many of the no-flap set are alsorenters, not paying directly for tires or brakes. But, mentioning that only fans theflames of righteous indignation, so I won’t.

Which Is Better, Full Or Reduced Flap Settings OnLanding?

I’ll give you the lawyer answer: It depends. However, inmost circumstances you are better off with full flaps.

My opinion on the subject began to form during some daysof research when I was flight instructing in college. A short distance across the rampfrom the FBO where I worked was the local FAA office (back then it was called the GeneralAviation District Office). During some lousy weather days I came to spend time talkingwith an FAA inspector. He was superb. He had retired from Pan Am after a career thatincluded service aboard flying boats and he believed safety was enhanced by talking withand counseling pilots, not leaning on them. He suggested I spend the crummy weather dayslooking through his office’s collection of accident reports. So I did.

I got interested in landing accidents and found that whereflap deflection on landing was recorded, the landing accident rate seemed to be inverselyproportional to the percentage of available flap being used. That is, the more flapdeflection used, the fewer the number of accidents.

I also noticed that most landing accidents were reallyrollout accidents. The pilots almost always managed to get the airplane onto the runway,then lost it during rollout.

After years of wrestling with just trying to hit therunway, the fact that the loss of control occurred later on was an eye-opener. The realproblem with a “landing accident” was not control of the airplane in flight. Itwas loss of control after touchdown, both on conventional- and tricycle-gear airplanes.

Control Thy Airspeed And Thy Direction!

Because of those days of looking at accident reports, I’vetried to pay attention to the flap-selection-on-landing issue over the years. I’velistened to a lot of arguments, read articles, watched one crash involving loss of controlafter landing and looked at a few airplanes that had run off runways. As a result, I’veformed some opinions on the use of flaps on landing. They may be imperfect, but they werenot arrived at hastily.

1. The cause of most landing accidents, no matter the windcondition, is not control of the airplane on final. While the cliche about a good landingfollowing a good approach is pretty true, as an instructor I see a lot of pilots, usuallynot student pilots, who are uncomfortable slowing the airplane down on final. They tack onextra knots for the spouse, the kids, the relatives and their favorite TV shows. Theywhistle down final at the speed of heat because that way the controls don’t feel sloppy.Excess speed, combined with the low wing loading of light singles, causes them to floatand start having problems with drift as the speed decays and the flight controls begin toneed more deflection at the lower airspeed. Or, they notice that they are running out ofrunway. The next step seems to be for the pilot to stick the airplane on the ground quitea bit above its stall speed. Sometimes the first part of the aeronautical anatomy to makecontact with the runway is the nosewheel.

2. The resultant landing accident is caused because thereis less rolling control than the pilot anticipates. There is pretty good aerodynamiccontrol, but the pilot simply does not use it. The mind-set seems to be that once on theground the aerodynamic controls are no longer relevant. “Hey, I’m on the ground, Ishould be able to rely on the tires to go where I want.” In addition, just aftertouchdown there is a huge tendency for nosewheel aircraft pilots to sit back with the”I made it” sigh. Much to their dismay, they discover the airplane doesn’t havesquat for rolling control when it is zorching along at or above stall speed. It is flyingmore than it is rolling.

Next time you are at the airport during a crosswind, watchthe landings and see how few pilots keep full aileron in during rollout. In fact, only aportion of the pilots out there taxi with the ailerons fully deflected in a crosswind, orremember to keep the elevator all the way up when taxiing on grass (the latter is veryrare if you watched the production airplanes at Oshkosh last summer).

During the early portion of the rollout flight controlsare still remarkably effective. We’ve all done slow flight at altitude, even while scaredto death about the whole concept, and noticed that the airplane was controllable. It justtook some relatively big control inputs to get the airplane to go where we wanted it. So,after touchdown, it is the flight controls which keep the airplane going in the desireddirection, not the wheels. Time and time again, the pilot applies a little aileron, butnot enough. The result is a sideways, hopping skid off of the runway into bent metal. Or,the pilot pushes the nose down in an effort to get rolling control which simply isn’tthere yet, and makes the main gear even lighter on the runway, slides the tires and goesoff the end. The TV cameras then come out and help our hero give general aviation anotherblack eye.

3. There is a window of exposure between the moment thataerodynamic controls lose effectiveness and the wheels develop it. At touchdown we stillhave pretty good flight control effectiveness if we are willing to use it. It willdiminish in effectiveness as we decelerate. When we are rolling slowly we have goodcontrol because the weight is on the wheels. That control gets progressively better duringdeceleration. The idea is to minimize the period where you have neither good flying norrolling control. How do you do it? Land as slowly as possible, decelerate quickly and putthe weight on the main wheels early. Landing slowly means you kept the airplane going inthe correct direction in the air through the judicious use of the flight controls. As aresult, the flight controls are positioned to help you out on the ground…think of thetouchdown as another part of the landing process, not the end of it (fly the airplaneuntil it stops moving, ever heard that before?).

From a behavioral perspective, pilots who fly at therecommended speed down final, with full flaps, tend to be in the habit of putting theflight controls where needed and to continue to do so after touchdown. It seems to be acause and effect event. Those who fly overly fast down final and need little controldeflection seem less likely to use aerodynamic control during rollout and more prone towreck airplanes.

Touching down with full flaps gives you the loweststalling speed. It also gives you an additional benefit: maximum drag so you willdecelerate as rapidly as possible with the power off, getting you down through that redzone of poor control rapidly.

While the FAA may frown on it as a negative transfer oflearning and cause you to run the risk of someday retracting the gear during rollout,raising the flaps about one-third of the way into the rollout helps put weight on to themain gear about the time the flap’s value for aerodynamic deceleration is running out.(Yes, you have been warned, if you grab the gear handle, you did it knowing the risk,don’t jump on me.) You get a triple benefit from using flaps: low touchdown speed, rapidinitial deceleration and a lift-dump device for putting weight onto the wheels to enhancerolling control.

But, What About Go-Arounds?

Someone always jumps in the discussion and claims that a________ (just fill in the blank) won’t climb with full flaps. That simply is not true forany general aviation trainer made in the last forty years unless it is a hot day inDenver. If the airplane will not climb with full flaps something is wrong. Check to see ifthe engine is developing static rpm as called for in the Owner’s Manual or POH. Check tosee that the propeller meets specs. Then check to see if the person flying is trying toclimb at too fast a speed. I agree that we seem to be having more go-around accidents inthe last few years than in the past. I suspect we have a problem with recurrent training.Pilots are not practicing go-arounds and have trouble with them when they need to do one.

A go-around from a balked, full-flap landing involvesimmediate application of full power, shutting off the carburetor heat and setting up thecorrect climb attitude while raising the flaps to the half deflection position. As theclimb continues, the flaps are moved to the position for obstacle clearance climb at Vxand then retracted after obstacles are cleared and speed is increased above Vx. In some ofthe recent flight reviews I’ve given, pilots have selected flaps up before applying fullpower. That seems to be a negative habit transfer from touch and goes. Sigh. Maybe it is agood reason to not do touch and goes.

What About Airplanes With No Flaps?

The light wing-loading airplanes with no flaps, other thanthe Ercoupe, have a fairly high landing accident rate. I’d be curious to compare the ratebetween the Piper J-3 Cub, which has no flaps, and the Super Cub, which does. The no-flapairplanes also tend to be tailwheel machines, which adds another variable to the issue oflanding accidents. They are more challenging to land; however, tailwheel pilots learnearly on that they have to fly the airplane until its tied down and thus tend to touchdown and keep the flight controls positioned correctly during rollout.

A Down Side To Full Flap Landings?

So what is the down side? The fact it takes more work toline up with the runway and make the touchdown. It requires more skill to land theairplane with full flaps. Is that a bad thing? Well, for some people, yes. There are thosewho refuse to keep their skills up. There are those who are lazy. There are those whosimply do not have the opportunity to fly as frequently as they desire to polish theirskills. Yes, I recognize that this flying stuff costs money and I have tremendous sympathyand understanding for this third group.

Looking beyond the seemingly obvious, the fact that ittakes more skill to get the airplane to the desired spot on the runway with full flaps isactually a benefit. It tells the pilot when he or she should not try to land on thatrunway. How so? Glad you asked!

Setting up the airplane on final at the recommendedapproach speed with full flaps and adding no more speed than one-half the gust factor putsthe pilot in a very good position to evaluate wind and runway conditions. (Gust factor isthe amount over the steady state wind the gusts are blowing. If the wind is reported attwelve with gusts to twenty, the gust factor is twenty minus twelve, or eight. Add half ofthis value, four knots, to your approach speed, and no more.) Hold the recommendedapproach speed plus gust adjustment and see if you can line the airplane up with therunway.

If you cannot, that is, you get either the aileron orrudder to the stop and still cannot control the drift, you are getting a message loud andclear. There is good reason to believe you will have significant difficulty controllingthe airplane on the rollout. Why buy trouble? That runway may not be a good one forlanding under those weather conditions.

If you can keep the airplane aligned with the runway youwill have the necessary aileron correction cranked in on touchdown. You can land on onemain gear, then go the rest of the way to full aileron deflection as you try to hold theother main off the ground. The deflected ailerons will help you keep the airplane goingstraight. (Adverse aileron yaw, remember?) The deflected ailerons will also keep theupwind wing down and avoid the wind getting under it to flip you over. The flaps will slowyou rapidly. As the nose comes down, the flaps can go up and, hey, presto, you have goodrolling control and the ailerons are to the stop where they should be. By the way, youhave saved wear and tear on tires and brakes.

Keep in mind that in this situation there is no magic tothe center line of the runway. If there is a lot of crosswind and lining up with thecenterline is proving difficult, seriously consider touching down on the downwind side ofthe runway and angling across it slightly, toward the wind, to effectively reduce thecrosswind angle.

Dealing With A Crosswind

Ok, you can’t line up with the runway with full flaps. Thewind is too strong. What do you do? You remember you are the pilot in command. You selecta runway which is more into the wind. It may be grass. Well, that may be why they built ashort grass runway at that airport, for those strong crosswind days. Haven’t landed ongrass? Why not? Go do it.

The next option is to go to another airport with a runwayaligned more into the wind. So you have to arrange ground transportation? It is far lessembarrassing than arranging to repair a bent airplane. I’ve checked.

If you do not have the fuel to get to another, moresuitable airport consider two other options:

1. Is there a taxiway oriented into the wind? Is it longenough to land on? With a strong wind it may not take much. You are in a situation wherecontrol of the airplane is in doubt because of the strength of the wind. Questionablecontrol defines an emergency situation. For crying out loud, use your judgment; landing ona correctly aligned taxiway of suitable length may be the safest thing to do. I haven’tfound that it violates any regulation. Even if it arguably does transgress a regulation,in an emergency you may deviate from the regulations to the extent necessary to deal withthe emergency.

2. As an alternative, if you have practiced it recently,you might try a portion of the Bob Hoover Tennessee Waltz landing. Come down final withthe flaps up and enough speed to keep the airplane aligned with the desired track on therunway in a side, not a forward, slip. Flare just enough to keep the nosewheel fromtouching down, then touch down on the upwind main landing gear, while still in the sideslip (remember, a side slip will track straight ahead because of the effect of the wind).This is the nosewheel version of a wheel landing in a conventional gear airplane. Keep theairplane on that wheel, power off, as long as you possibly can. That means you willprogressively move the control stick or wheel all the way to the side and aft. Only afteryou have full aileron and elevator deflection will the downwind gear and nosewheel touch.At that point you can relax the elevator pressure a bit, but not the aileron. You’ve doneall you can with the flight controls, keep them there and hope you can keep it straightuntil the wheels quit sliding sideways and the tires get some bite.

Am I being inconsistent by suggesting a landing with noflaps after a long discussion of the benefits of full-flap landings? Perhaps. The flaps-uplanding increases the loss of control exposure on roll out. The idea is to get the pilot’sfull attention focused on the crosswind and the need for full aileron deflection aftertouchdown before making the conscious decision to land the airplane flaps-up. Then, andonly then, is the pilot ready to do what is necessary to put the airplane where desiredand not be a passenger.