The Pilot's Lounge #102: The Last 10 Feet
The dreaded 709 ride -- it's just the FAA ''here to help you,'' but your ticket could be on the line. AVweb's Rick Durden helped one pilot brush up on his skills and remind himself the best way to land.
The virtual airport, home of the Pilot's Lounge, is much like any other little airport in the country. As with other modest, general aviation airports, we occasionally have the aeronautical version of the fender bender, where someone skitters off the side or end of a runway and comes to a somewhat ignominious halt.
One of our pilots suffered a certain embarrassment a few weeks ago when landing in a gusty crosswind. He put the airplane on the runway but couldn't keep it there. He took out one runway light and eventually stuck a wing into a fence, causing minor damage to the airplane. He was mortified. He had his family in the airplane and is going through a lot of soul-searching about whether he should continue to fly. He's even wondering whether his family will ever travel with him again.
The FAA Is Here To Help
The FAA was alerted, and looked things over, even though the incident did not meet the definition of an accident under Part 830 of the NTSB regs. The FAA inspector assigned required that the pilot take what is called a 709 ride. That's a procedure under the regulations by which a pilot has to demonstrate his or her competence in an area of flight operations. Nineteen times out of 20 it's no big deal whatsoever (although the pilot will be sweating bullets). The inspector and the pilot will sit down and discuss the flight operation in question and then go fly for a short time. The pilot demonstrates that he or she can fly, the inspector fills out the necessary paperwork, everyone involved goes on to other things and life proceeds apace.
This time, the inspector had the pilot give me a call before he came in for the 709 ride and recommended that the pilot get some dual in crosswind landings. Each FSDO has a number of safety counselors -- pilots with some degree of experience -- who volunteer their time to assist the FAA in getting the message out regarding safe operations. Apparently my name drifted to the top of the stack so I was the one who got the call from the pilot.
Recipe For An Incident
I've changed a great deal about this event so the persons involved cannot be recognized. Our friend, I'll call him "Buzz," was pretty nervous when he called me and told me what was going on. We got together where we would not be overheard to talk about the accident and crosswind landings in general. Over soft drinks Buzz told me that he'd owned his Cherokee 180 for 15 years and put about 50-75 hours on it a year. He had an instrument rating but wasn't current. He'd had a flight review 20 months ago. He said that on the day things went wrong, the wind was blowing from about 180 degrees at 8 knots with gusts to 15, according to the ASOS. There were airplanes in the pattern. They were using Runway 12, the paved runway. That gave them a 60-degree crosswind, not out of line at all and well within the capabilities of the airplane.
I asked Buzz whether he had considered using Runway 18. He said he hadn't because he just never used the grass runway and that, as he approached the airport, he had been listening to Unicom and three or four airplanes had either taken off or landed and all were using Runway 14. He didn't want to cause confusion in the pattern. Buzz went on to say that he left the flaps up because the airplane would feel really sloppy on final with full flaps, plus he wanted to tack on some extra speed so that he had better control in the gusts. I asked him what the normal approach speed was for the airplane. His response was 10 mph faster than what is published in the flight manual. He also said he normally lands flaps up because there is plenty of runway and he has better control of the airplane at the faster landing speed.
We agreed that I would not make any comments on his technique or approach to flying his airplane until we had made a short flight together. We decided to go out and shoot a few full-stop landings on Runway 12, as there was a light south wind, so we'd get the same sort of right crosswind that he'd had that day. (His airplane was out of the shop; the mostly cosmetic damage had been repaired.)
Buzz came down final at about 95 mph indicated airspeed, in a fairly flat approach, with power. Over the fence he brought the power back a little. He flared just slightly, floated quite a ways, touched down, then immediately pushed forward on the wheel to pin the nosewheel on the runway and closed the throttle. The touchdown was relatively smooth but we had started to drift left as we floated and we touched down with a noticeable side load on the gear. We used the entire runway getting stopped. During the first several hundred feet of the rollout the airplane darted from side to side, keeping Buzz pretty busy with the rudders and the brakes. The next two landings were repeats of the first: noticeable float, slight loss of directional control, touchdown in a slight crab with the right wing slightly low, nose wheel immediately pinned on the ground and power reduced to idle, followed by rolling the full length of the runway with some side-to-side excursions as Buzz fought the crosswind.
We parked the airplane and I crawled underneath the right wing. The right main tire had a number of small flat spots, where it had locked up during braking. I walked around to the left side and noticed the same thing with the left tire. I asked Buzz how much use he got out of main gear tires. He looked at me and said, "My mechanic usually has me change them at each annual. The just don't seem to last any time at all. I guess I hadn't noticed the flat spots. I wonder if the brakes need to be bled, they must be grabbing."
Buzz and I went inside and we sat down where we could have a little privacy. We had brought the flight manual in from the airplane and I turned to the Before Landing Checklist. I told Buzz that I'd observed he flew final about 15 to 20 mph faster than the speed called for in the manual and asked why he'd chosen the speed he used. He told me that it was because when he slowed down he didn't like the way the airplane handled and, in a crosswind, he was concerned about successfully lining up with the runway.
We talked about the energy that he had to manage in touching down at something like 75 or 80 mph. The airplane was most assuredly flying when the gear started rolling. Even when he lowered the nosewheel to the pavement, that fat, high-lift wing was still doing its thing. I suggested that the reason for the flat spots on his tires was that there was very little weight on the gear, so even light braking was likely to cause a wheel to lock up. I also mentioned that because the airplane was still moving at well above its stall speed, it might be a good idea to continue using the aerodynamic controls to urge it to go in the desired direction. I said I had noticed that, up until touchdown, he had some right aileron deflection applied. I asked him why. Buzz said that it was because he had to do a bit of a side-slip to keep the nose pointed down the runway and the airplane from drifting to the left. I agreed. That's a fairly normal side-slip crosswind-landing technique that has worked well for generations and will probably continue to do so for the foreseeable future. That being the case, I asked how come he had centered the ailerons the moment the wheels hit the ground. Buzz thought for a moment and said that once the wheels were on the ground, his thought process changed over to rolling control of the airplane because the airplane was no longer in the air.
We spent a little time talking about just when that airplane was done flying during the landing sequence. With his 75 mph touchdown and a stall speed down in the 55 mph range with the flaps up, the airplane certainly wasn't done flying for at least the first 20 mph of post-touchdown deceleration. If Buzz were to pull the wheel back, the airplane would come off the ground. In fact, if he pushed it forward only a trifle more enthusiastically than he was doing, he would cause the mains to lift off and the airplane would roll along on the nose gear. Wouldn't it make sense to continue to use the flight controls to help prod the airplane straight ahead down the runway? Buzz agreed that maybe keeping the ailerons deflected into the wind, as they were on touchdown, would be a good thing.
I then asked Buzz which way the airplane tended to turn on rollout in a crosswind. Right away he said, "Into the wind ... to the right, in the case of the landing we'd just made."
I followed up with, "OK, if you are using right aileron for the crosswind, what rudder deflection do you need?"
"That's easy: Left rudder to keep the airplane from turning right."
"Precisely," I said. "Which way does application of right aileron yaw the airplane?"
Buzz thought for a moment. "Well, when I roll in right aileron I have to apply right rudder to coordinate the turn, so the aileron deflection yaws the airplane left."
"Go to the head of the class. Now, if right aileron is needed for a right crosswind, and right aileron yaws the airplane to the left, doesn't that help you with control of the airplane during rollout? Doesn't that right aileron deflection keep the wing that's into the wind down and also help keep the airplane from weathervaning to the right, into the wind?"
I could see the light bulb light off, "Yeah. Good grief, I learned that years ago with my primary instructor. If I keep the aileron deflection in, I get good things all the way around. It helps with directional control and it keeps the upwind wing from lifting in a gust ... and with all that dihedral, that could happen."
"So, what do you think should be done after touchdown in a crosswind?"
Buzz said, "Geez, I feel silly, this is pretty basic stuff. I've got to remember to roll in all the right aileron after touchdown and keep it there."
"Yep. That's why we're here: This is all stuff you did once upon a time, but got out of the habit of doing. You have to keep flying the airplane until it comes to a stop, and that means full aileron deflection into the wind during rollout. And, yes, I know the old-timers say that Cherokees are immune to crosswinds because of the wide gear and so forth, but if you look at the accident statistics, they've got a lousy rate of loss-of-control-after-touchdown accidents, just like all other general aviation singles."
Inevitable Loss of Control
We got on the Internet and looked up accidents for the PA28 series aircraft over the last few years. We found that there were a bunch involving successful touchdown on the runway, with subsequent loss of control.
"Buzz, I'm going to suggest to you that the problem with crosswind landings is not in lining up with the runway, it's loss of control once the airplane has touched down. I'm going to go further and suggest that loss of control on rollout is due to two major factors: first, touching down so fast that there is tremendous amount of energy to manage; and second, failure to use the aerodynamic controls to manage that energy, while relying on the nosewheel when the airplane is going too fast for it to be effective.
"Let me suggest that you don't really have very good rolling control in your airplane until you have slowed to about 30 mph or so. You're riding a tricycle and it needs to have weight on the wheels. You've got a high-lift wing that is still providing noticeable lift down to something below 40 mph."
Buzz considered the suggestion for a while and said, "I'll buy that."
"Now, if you don't have rolling control until you are down to about 30 mph, how do you keep the airplane going straight?"
"The aerodynamic controls, mostly the rudder and ailerons."
"Buzz, on your airplane, which of the controls seems to stay effective to the lowest speed?"
"It's always seemed to me to be the rudder."
"I agree. So why be in a hurry to put weight on the nosewheel when you've got good rudder control and you risk picking up the main gear and really getting yourself in trouble?"
"Good point," Buzz said. "I know there is a direct steering link on the Cherokee, so I've always put the nosewheel on right away. Maybe that's not such a good idea."
"What did the guy who checked you out in your airplane say about landing it?"
"Well, he was just a kid, and I didn't pay that much attention to him, but he said I should not rely on the nosewheel. Maybe the kid was right."
"Buzz, I think he knew more than you gave him credit for."
Too Much Speed to Stop
I thought for a moment, then went on: "Let's talk about your touchdown speed. Once you put the wheels on the ground, you've got to decelerate to about 30 mph before you've got decent rolling control and you have enough weight on the main gear to get good braking action, right?"
Now, if we touchdown at 75 mph, we've got to decelerate through 40 mph of decreasing aerodynamic control and slowly increasing rolling control, right? Would you agree we're dealing with a 40 mph zone of deceleration in which we've got funky control authority; it's changing in effectiveness constantly and, from those accident reports we looked at, is a zone in which we are at significant risk of loss-of-control on the runway?"
"If you put it that way," Buzz said, "I have to agree with you."
"I don't want to put words in your mouth or suggest a concept with which you don't agree, so let's work through it," I said.
But Can You Explain It Yourself?
Buzz drew on a piece of paper and said, "All right, I touch down at 75 mph and the airplane is still flying. I've been centering the ailerons, so I've completely lost aerodynamic control; I'm not keeping the upwind wing down and I don't have the benefit of the yaw from the ailerons. I'm completely relying on the ability of the friction of the landing gear on the runway to keep me going straight, except for the fact that friction is pretty minimal until I've scrubbed the speed down to about 30 mph."
There was a pause, Buzz rubbed his chin and looked at me, "It seems to me that even though I am getting a little smarter and am going to use the ailerons on the rollout, I'm still dealing with 40 mph of exposure. Wouldn't it make more sense to touch down at a slower speed, so that my deceleration exposure is shorter?"
"Buzz, you're way ahead of me. What's the stall speed of your airplane with full flaps?"
"Are you nuts? It handles like a drunken pig with full flaps."
"Let's just deal with one issue at a time. What's the stall speed with full flaps?"
"I don't know for sure, probably around 50 mph, or maybe a little less," Buzz said with some hesitation.
"Before you get all excited, let's just consider it hypothetically. If you touch down at 50 mph, with full flaps, right at stall speed, with the aileron in for the crosswind, and you move the ailerons to the stop just after touchdown, how do you think the airplane is going to handle on rollout? No, I can see that you are getting excited; let's not talk about the runway lineup yet, just the rollout."
"Well, if I touch down at 50, I've only got 20 mph of exposure until I've got good rolling control. And if I retract the flaps after I touch down, I'd put more weight on the wheels right away and maybe help things out."
"That sounds good to me, Buzz. In all of those accident reports we didn't see any that said the pilot lost it on final and crashed off the side of the runway, did we? The problem we are facing is not loss of control in the air; it's loss of control on the ground. It's a far worse problem than any issue of lining up with the runway."
I looked at Buzz and suggested something: "Let's say that you've got a crosswind here at home base. The first thing we put into the landing equation should be the selection of the runway that is most directly into the wind, right?"
"Well, OK, that makes sense."
"Yeah, on hindsight it's a no-brainer, isn't it? We'll go do some takeoffs and landings on the grass runway tomorrow. The next step is to touch down going slowly. So, we're going to work on that as well."
"Rick, I'm not convinced about either one of those ideas, but I did tear up my airplane touching down fast on the paved runway so I'm willing to listen."
The next day we scheduled two flights. On the first, Buzz and I went to altitude and he flew his Cherokee around with full flaps at 60-65 mph indicated airspeed. At first I felt as if I'd told him to point a cocked, loaded gun to his own head. His reaction was pretty normal: He was scared spitless of stalling the airplane. I thought back to my time before I did any aerobatics and how scared I was of slow flight and stalls. The airplane seems to wallow through the sky: Massive control inputs are needed to get a response and the airplane responds as if the control wheel is in a bowl of oatmeal.
After a few minutes Buzz started to relax. He'd figured out that the control forces were the same at slow speeds as at cruise; those forces just resulted in more control deflection. He found that he could control his airplane just fine with the stall warning blaring away. He made the necessary control inputs to make it go where he wanted it to go.
We then made several landings on the grass runway, with full flaps. Buzz didn't like slowing below 90 mph on final so I suggested he turn final at 90 but then slow to 70, with full flaps, by the time we were 10 feet up and just about to start the flare. I also suggested that as he started to flare, he should close the throttle.
The landings were not terribly smooth initially, but we also didn't float down the runway the way we had. Buzz had to relearn the skill of raising the nose of the airplane as he closed the throttle and not depend on power to arrest the descent. Flaring to land is every bit as effective as carrying power all the way to the ground in terms of generating a smooth landing and has a number of added benefits: Less runway is used, the airplane floats less so it is less likely to be affected by the crosswind and be drifting at touchdown, and Buzz was going to get more life out of his tires.
By the time we'd made four or five landings, Buzz was touching down and stopping well within the confines of the grass runway, probably using about 1,500 feet all told. He also said that he was surprised at how little braking he needed to do.
We took a break and discussed grass runway landings. Buzz said he didn't keep track of the condition of the grass runway because he didn't use it. I pointed out that on a windy day, even if the grass runway is a little soft, if it is into the wind, it is probably preferable to an exciting ride on the pavement. We also talked about how it felt to slow the airplane down to the published approach speed, about 1.3 times Vso. Buzz was frank about his discomfort with the relative sluggishness of the airplane and again expressed worry about being able to line up with the runway in a crosswind.
"Buzz, the manufacturer demonstrated crosswind landings in over 10 knots of direct crosswind, so we know what the airplane will do. What is your own personal limit for crosswinds?"
"I've never been willing to go as high as 10 knots if it's a 90-degree crosswind."
"Sounds smart to me. So, we know the airplane has a capability that exceeds what you're comfortable with. Let's figure out a working personal limits number by going out and doing some flying where we touch down slowly. By setting up a personal limit number where you can safely line up with the runway and touch down slowly, you minimize the real risk: running off of the runway after touchdown. If the crosswind component is higher than the number that you've set for yourself, you either land on another runway or a taxiway that is into the wind, or you go to another airport. Heck, there are two that are within a 40-minute drive from here, so it's not as if you are going to have to go to the next state."
Back On Pavement
After I let Buzz buy me lunch, we got back in the airplane. The winds were gusting nicely out of the west, giving us a left crosswind on Runway 30 with a direct component of about 5 or 6 knots, meaning Buzz was going to have to work. We talked about the rule of thumb of flying the normal approach speed and only adding half the gust factor. This time the winds were at 12 with gusts to 22. The gust factor was 10, so we were going to add no more than 5 knots, or with his old airspeed indicator, 6 mph. Buzz wasn't happy about the low number he got. I said that adding speed was to prevent stalling, something that wasn't much of a risk with that fat wing and the instantaneous power response of a prop-driven, piston-powered airplane. The real concern was too much speed, which would cause us to float and give us time to start drifting sideways before touchdown, something that is described in far too many accident reports, followed by, "... the pilot was unable to maintain control on rollout and departed the runway."
In the air Buzz flew a more precise pattern than he had been. Either the practice was paying off or he was being more assertive with his airplane. Maybe both.
Turning final, Buzz pulled on the final notches of flaps. His speed was about 15 mph above our target, and he was slowly decelerating. That's just fine: Constant speed approaches on final aren't necessary unless flying a jet and Buzz would really be working if he flew 1.3 Vso plus half the gust factor all the way down final.
It was bumpy and he was working to establish a crab that would allow us to track toward the runway. As we got closer his speed slowly worked its way down toward his target and Buzz started to transition into a left-wing-low slip. He was playing yoke and rudder well. At 10 feet above the ground he was just about to the threshold of the runway, speed was spot-on and he slid the throttle the last half inch to the idle position. As he did so, he raised the nose a little to keep the rate of sink from increasing and then a little more to start to break the descent. He flared, nose high, and the airplane floated only a very short distance, not enough for it to start to drift. The left main touched as the stall warning began to sound. Buzz rolled in full left aileron and held it. He kept some back-pressure on the wheel to keep the weight on the mains. I could see he was working the rudder pedals to keep going straight, and I was impressed that the centerline always stayed between the main gear.
We decelerated nicely and Buzz fed in a little brake. To his surprise, he had to come off the brakes to roll to the mid-field turnoff. He turned off and stopped, looked at me and gave a heartfelt, "Whew. That was work."
"Crosswind landings are work, there's no other way to describe them. Let's take a moment here to relive it. First, did you ever hit the stops on the ailerons or the rudder while you were still in the air?"
"No, I never did, but after out talk, I was willing to put the controls to the stops if I needed to get the airplane where I wanted it to go -- and that's something I don't ever recall being willing to do."
"You had the speed under control nicely, and you were at your target speed as we came through 10 feet above the ground. Before you got into the flare you closed the throttle and you raised the nose to stop the descent. The result was that you touched down very slowly and the airplane was all done flying. You put the aileron to the stop and used the rudder assertively to keep the airplane straight and almost immediately you had effective braking because the flaps made you decelerate faster and the wing wasn't flying any more. Let's go do it again."
Practice The Right Way
We made five more landings, each one proving the first wasn't a fluke. Some involved a very firm touchdown and Buzz absolutely rolled two of them on. I emphasized that I did not care very much whether a crosswind landing was smooth or fairly hard; what I cared about was that the airplane was not drifting at all at touchdown, that it was pointed straight down the runway and there was no side load on the gear.
After we flew, Buzz and I chatted some more. I emphasized again that the most common error made by pilots in crosswinds is to go too fast. Speed is not your friend because the perceived problem on a crosswind landing is not the real problem. Folks get all worried about having enough control authority to line up with the runway and figure that extra speed will help. The true problem rears its head once on the runway when they've got a lot of excess speed, and energy, and very little friction between the tires and the runway. To add to that problem, those very same pilots tend to have a mental switch that goes from "flight" to "ground" mode the instant the wheels hit and so they stop using the flight controls. The consequences are depressingly predictable and familiar.
I suggested to Buzz that the key to a crosswind landing is to come into the last 10 feet above the ground with full flaps, right on the desired speed and ready to close the throttle and flare to the landing while controlling the drift. How he got to that last-10-feet spot wasn't particularly relevant: He could be decelerating gradually to the target speed or hold the speed all the way down final. He could fly a long or a short final or turn all the way from downwind. Getting to the last 10 feet with everything collected was all that mattered. If, at that point, he was not on speed, or was having difficulty with the lineup or it just didn't feel right, that was the time where I recommended he make a go-around rather than force the airplane onto the runway and risk the classic loss-of-control-on-rollout accident.
As we finished up, I also made a recommendation to Buzz that he fly with a CFI twice a year -- either get an hour of dual or take a half day and get a full flight review. Because he doesn't fly all that much each year, the refresher may help keep him from sliding back into some of the less-than-stellar habits he'd developed.
We shook hands and Buzz departed. A few days later he called me to say that the 709 ride was a piece of cake and that the inspector had complimented him on his crosswind technique.
See you next month.
Want to read more from Rick Durden? Check out the rest of his columns.