Working with wind: how much wind you can handle depends on the airplane and the runway.
It had been fairly smooth at altitude. But the weather was post-frontal, and the ATIS described an easterly surface wind huffing and puffing at between 15 and 25 knots. The good news was there were plenty of runways at KMCO. The bad news? They all were oriented north/south. Landing at the nearest airport with runways oriented into the wind would mean I'd miss my airline connection.
WHEN WIND BITES
The touchdown, performed with half flaps and a bit more airspeed than normal, was textbook. We were sailing one wing into the wind, with opposite rudder in a side slip, just the way my instructor had taught me. It's what happened next that smarted.
As the pilot slowed the airplane, aiming for a high-speed turnoff strongly suggested by the tower controller, she relaxed her full-aileron control inputs, which had until then correctly held firm against that wind. That's when the wind got us. A big gust lifted the upwind wing and tipped the Cessna high onto its downwind main gear. We were close to being on our back.
Fortunately, the pilot quickly responded with aileron into the wind and, also fortunately, the wind died down. The airplane slammed back down onto all three wheels and we sat there, stunned, the rush of the morning suddenly lost in the horror of what almost happened. A grumpy ground controller suggested getting off his taxiway, and we snapped out of it, rolling tentatively, and with full control input against the wind, into the FBO. I learned to respect crosswinds in a whole new way that busy morning.
It turns out that NTSB data collected during an 11-year period picked wind as a primary cause in some 2800 accidents, most of which occurred on landings. The key culprit? You guessed it: crosswinds. In fact, statistics show nearly 20 percent of taxi accidents in the NTSB database are also caused by wind. Getting cross with the wind and running out of control authority--even with full, correct control inputs--easily can happen to personal aircraft on the ground.
A few years later, I was turned on to flying airplanes built in a taildragger configuration. They fly exactly the same as tricycle gear in the air, but on windy days their weathervaning propensity is legendary. I flew an ultralight and quickly discovered that you didn't need much wind at all to pick up one of its gossamer wings. The lesson sunk home the day I stood next to the leftovers after a neighbor flying his Carbon Cub caught a gust just on touching down. It sent him careening back into the air without the airspeed to stay there. The aircraft stalled and pitched down, with no room for recovery. A moment later, he was hanging from his five-point harness with the propeller embedded in mud by the side of the runway. It only took one precisely timed 15-knot gust on a narrow runway to get him there.
THE BEGINNING AND THE END
Wind isn't always so devilish to pilots. Sometimes, in fact, wind can be a pilot's friend. When? Well, how about a nice steady 30 knots on the nose when you need to land short? Aircraft carrier pilots practically demand that (and Alaskan bush pilots certainly appreciate it, too). When aloft, a tailwind can save both time and money, blowing you to your destination with blustery if not smooth efficiency. It's when the wind isn't particularly lined up in the direction you need it, and when it gets puffy, or downright howling, that flying with it gets more complicated for light plane pilots. Actually, heavy iron gets challenged, too. Spent any time on YouTube lately? Google "crosswind landing" and see what you've been "missing." It's humbling.
Yet, my feeling after watching a compilation of those hairy landing videos is, wow, that was so unnecessary. Why? Because the crews knew or should have known what was coming, and, frankly, because testing the limits of your crosswind skills and the airplane's capabilities with a bunch of innocent passengers is just bad judgment in my opinion.
Yeah, you heard me. Those airline pilots had the chance to see the forecasts for their destinations well in advance, and the abbreviations WND and G were there, indicating winds of more than 25 knots and gusts. A look at the isobars on any prognosis chart indicated the intensity of the weather, and the wind at the time of their arrivals. The arrival information is broadcast by the towers, and even if there was no tower, there were certainly wind socks and other clear indicators of how the surface winds were behaving.
We've tackled the problem that wind can present at altitude (Blow Wind, Blow, January 2012), so we'll limit our discussion here to the challenges wind presents pilots close to the ground, namely, wind shear and crosswinds.
Unfortunately, watching YouTube all day won't make you good at handling wind. Neither will flying your basic aviation training device (ATD), such as a stationary PC simulator. Even Redbird, builder of light plane ATDs with motion, found that simulating real crosswinds required something altogether different. The company developed a purpose-built motion simulator designed specifically to teach crosswind handling. It encompasses large-screen displays and a pivoting, twisting pilot seat and control console on rails.
Fascinating. You could really feel yourself in a hard side slip, tilted over, with controls crossed, flying down a glideslope, and you could see and feel yourself in a significant crab into the computerized prevailing wind. Honestly, the ATD did a good job of creating the kind of sideways, look-over-your-shoulder-at-the-runway or cross-control monkey business that gets pilots in trouble on windy days.
It's unlikely, however, that your local flight school has access to the Redbird crosswind simulator, so your best defense against wind is practice. Let's start with taxiing. Think back to the crosswind circular diagram from the Airplane Flying Handbook, reproduced at the top of the opposite page. "Pitch up and bank into the wind" is bow I describe control surface direction on taxi with a crosswind/headwind component. Got a tailwind component? Then it's "pitch down, bank away." Direct crosswind? That's "neutral pitch, bank into upwind side, or even neutral bank." It takes practice to get the swing of it as you "fly" the controls with your hands while taxiing with your feet. Every turn means you need to rethink the control position, and there is no room for laziness. Remember, one good gust could tip you into the grass beside the taxiway.
Positioning the controls for taking off in windy conditions essentially is the same as when taxiing. As the aircraft lifts off the ground, controls should be adjusted toward their neutral, climb position. If you did it right, the airplane will climb out perfectly crabbed into the wind. Of course, gusty conditions close to the ground may tax you for a few moments, but if you can ride it out through 1000 feet agl, you're likely to find smoother conditions as you climb.
DEMONSTRATED BY WHOM?
High wing, low wing, mid-wing, whatever. The statistics show that every type of airplane has succumbed to crosswind conditions at one point or another. Some say it's a bit easier for the wind to topple a high-wing aircraft, but then, watching low-wing aircraft drag a wingtip on a crosswind landing tells me that configuration has its issues, as well.
What's important is understanding what your aircraft's and your own limitations are. The aircraft came with a demonstrated crosswind component. This is the maximum amount of direct crosswind the airplane can "sail" against and stay straight aligned with a runway centerline, as demonstrated by a sharp factory test pilot. So you have to ask yourself before you even look at that number, are you a sharp factory test pilot? If not, you might want to brush up on your skills performing side slips and crabbed approaches to landing, or consider imposing a personal crosswind limitation somewhat less than whatever your airplane's stated limit might be. A bit rusty? You may want to do both.
If yours is a light high-wing machine, such as a Cessna 172, the demonstrated crosswind limitation is probably somewhere in the range of 15-17 knots. Even the low-wing Bonanza sports a demonstrated crosswind component of just 18 knots. And if your airplane could qualify for the antiques and classics line at EAA AirVenture Oshkosh? The FAA's Flight Training Handbook from the pre-POH era recommended using 20 percent of the published stall speed as the maximum allowable crosswind component, so an aircraft that stalls at 60 knots can handle a direct crosswind of 12 knots.
Note the handbook used the terminology "direct crosswind." That's a 90-degree angle, with the wind direct off your wingtip. Odds are that unless you deliberately pick your runway lined up as such, your crosswind component will be less than 90 degrees. This means your airplane can handle a bit more than the number designated as your direct crosswind component. How do you calculate this? Once upon a time we used an E-6B flight computer. Few newer pilots have ever seen one, though. Today, my EFIS breaks down the wind into cross- and headwind (or tailwind) components. Others might use the wind calculator built into their favorite electronic flight bag application. The point is: calculate it.
Once you've estimated the crosswind component (it will always be an estimate because no one can tell you for sure what the wind will be the moment you touch down), you have a decision to make. Do you, the pilot, have the skills to make that landing? And is there any way to reduce the crosswind so that it becomes less of a problem?
GET IT INTO THE WIND!
Honestly, I don't care if you prefer to slip to a landing over crabbing it in and kicking it out at the last moment, or some spastic combination of the two. I'm more concerned with doing all I can to get rid of the crosswind. What do I mean? I always ask myself, "Is there another runway better lined up with the wind on which I could land?" If the answer is "yes," then I demand that the tower let me land on that runway.
Even if it's a grass strip crossing the paved runway, which is often the case at rural airports, I stand a better chance of landing safely on the grass and into the wind than I do fighting a direct crosswind. And if the runway is wide--like the one my pilot had at KMCO that day--well, I cut across it at an angle into the wind.
Yes, I abandon the centerline this time, and land at an angle as best I can pointing as much into the wind as possible. Sometimes, I can touch down in such a manner that my rollout is perfectly aligned with a high-speed turn off from the runway, affording plenty of room for slowing before the intersecting taxiway. That's called planning.
Speaking of which, you can always declare an emergency and land on a taxiway that is more closely aligned with the wind. Yes, the tower controller will be annoyed, but not nearly as annoyed as he or she would be if you were to run off the runway, taking out a couple runway lights as you go, closing the airport for an hour while they drag the remains of your bird back to the ramp.
The reality is simple: There always is a way to land into the wind and eliminate the possibility of exceeding either the airplane's or your own crosswind limitations. You do, however, have to have the foresight and discipline to execute either a diversion to another airport (ostensibly with runways aligned with the wind), request for an alternate runway or taxiway, or modified landing technique.
As for wind shear, my advice is to avoid it. If you don't understand the dangers, see the sidebar on page 6. Proper preflight planning and in-flight weather monitoring can help you predict when and where you'll encounter a shear. Light airplanes have no business being anywhere but tied down when a gust front approaches. If that's not possible, try to stay in the air at an airspeed and altitude affording adequate ground clearance to recover from a windshear episode. That means going around if the guy ahead of you reports it. Sometimes you can wait it out, such as when dealing with garden-variety Florida thunderstorms, which usually are isolated and short-lived. Often you can divert to a less-windy airport, especially if your preflight planning allowed for adequate fuel to an alternate.
Wind is out there, but accidents attributed to wind, particularly landing accidents, are eminently avoidable. So plan ahead, and be the guy who doesn't have a sad story to tell.
Amy Laboda is a freelance aviation writer who holds an ATP and CFI. She and her family fly an RV-10 and a Jabiru-powered Kitfox.
BY AMY LABODA
Wind Shear Is Another Matter Altogether
On August 2, 1985, Delta Air Lines Flight 191, a Lockheed L-1011, crashed while approaching the Dallas/Fort Worth International Airport, Texas. While passing through the rain shaft beneath a thunderstorm, Flight 191 entered a microburst, which the crew was unable to traverse successfully. Of the 163 aboard, 134 passengers and crew died; 26 passengers and three cabin attendants survived.
The NTS8's probable cause determination included "the flightcrew's decision to initiate and continue the approach into a cumulonimbus cloud," which they observed to contain visible lightning, and "the lack of specific guidelines, procedures, and training for avoiding and escaping from low-altitude wind shear; and the lack of definitive, real-time wind shear hazard information."
While the inertia characteristics of an L-1011 differ greatly from the typical personal airplane, windshear encountered during takeoff and landing can slam any airplane right back onto the runway--or worse. I was in the pattern at Panama City, Fla., just before the gust front for a rather impressive squall line came through. As I was settling into the downwind, a departing pilot let out an audible "WTF!!" He wobbled airborne just as the wind disappeared from under him, shearing by more than 20 knots from headwind to nothing at all, then to a tailwind. I don't know how he stayed in the air. Immediately thereafter, tower told me to turn and cross midfield to re-enter the pattern for the opposite runway. The air got choppy and the windsock was dancing, but at least my landing was into the wind.
Call them microbursts, windshear or gust fronts, they all are essentially rapidly descending air from violent storms that rushes down, hits the ground and flares outward at speeds sometimes double the winds inside the storm. And since the winds spread in a rough circle around the storm's base, it's almost sure to swing the direction of the windsock.
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|Title Annotation:||STICK AND RUDDER|
|Date:||Feb 1, 2015|
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