Crosswinds And Airport Design

At one time crosswinds mattered a lot. The first landing fields were—well—fields. Pilots could opt to land into the wind because the airport was just an open space.

When paved runway airports were built multiple runways were included where space allowed. Even small general aviation airports usually had a short “crosswind” runway, even if it was sod instead of paved. And when the military built hundreds of airports during World War II most had three runways arranged in a triangular shape so no matter which way the wind blew the crosswind component was minimal.

But as traffic intensity increased it became clear that intersecting runways—or intersecting final approach and departure paths—put strict limits on airport capacity. The only way to maximize airport capacity is to make all runways, or at least the primary runways, parallel. As for crosswind, that’s the airplane designers and pilots problem.

One of the first modern, actually on purpose major airports to be built in the country was Washington Dulles. In the late 1950s Congress authorized construction of a new Washington area airport and the new airport would reflect the latest in design as the world was entering the jet age.

Planners recognized that a new airport would need lots of room and not be confined by the cities that had grown up around the existing airports so Dulles was located far west of Washington in what was then pretty much pasture land. The long runways were oriented north and south and more than a mile apart so simultaneous operations could be conducted on each. As a sort of throwback Runway 30-12 was stuck out to the west of the main part of the airport, but clearly the focus would be on the parallel north-south runways. The extra land that was included in the original plan had room for more north-south parallels and a third runway opened a few years ago.

Since Dulles was built a few other from scratch airports have been constructed including DFW, MCI and DEN. And at other major airports close parallel runways have been built to existing parallel runways so airplanes can depart on one close runway just as soon as another airplane is down and rolling on the other.

My point is that at many, and maybe soon, most airports, you will have some crosswind for every takeoff and landing because the runways all point the same way and it’s rare for the wind to blow right down the one and only runway direction more than a few days a year.

The eternal crosswind on modern airports has made for lots of great YouTube videos of airline pilots landing with fierce crab angles, tires smoking, airplane swerving to a stop. I’m not sure what begat what when it comes to airline jet crosswind landings. Did airport designers do away with crosswind runways because airplanes can land with a strong crosswind, or did airplane designers create airplanes with more crosswind tolerance because runway limitations demand it? Whatever happened first, pilots now routinely land with crosswind components that would have been unimaginable in the DC-3 days.

The reason I was thinking about crosswinds and how common they have become is because I wanted to land on Runway 27 here at Oshkosh the other day. I always want to land on 27, or the other way on Runway 9 because it is a very short taxi into the EAA Weeks Hangar north of the runway. It takes forever to taxi in from Runway 18-36. The wide separation between the two primary runways here at Oshkosh is unusual, and it is one of the many design aspects of the airport that make it work so well as host to AirVenture.

The wind was reported at 330 degrees, 14 knots, with gusts to 20, when the controllers told me to expect Runway 36. I really wanted to land on 27. I didn’t look up the actual crosswind component on the graph in my pilot’s manual, but I guessed that the angle was about two thirds of the way to a direct crosswind so the 20 knot gust would be a crosswind component of 14 knots, about two thirds of 20 knots. When I checked later the crosswind component in the 20 knots gust was more like 17 knots, but still well below the Baron’s demonstrated crosswind capability.

So, I thought, real pilots land in much more crosswind than this all of the time. The airplane can handle it, and after so many hours and years in the same airplane, so can I so I asked to land on Runway 27 and the tower approved. With flaps at approach instead of full down the landing was just ordinary.

Every airplane has a crosswind limit, and it can be very low in light taildraggers, for example, but for many of us a crosswind is just another day. And if airport planners have their way, the oddity will be a landing without some aileron and rudder action.

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18 Responses to Crosswinds And Airport Design

  1. Pete Zaitcev says:

    And what do you know, a 737 was blown off the runway by a 50 knot crosswind at DEN last year. Cheers to the modern design!

    • W.G. Landry says:

      Guess he never attempted a landing at KSAW (K.I. Sawyer airport). Always a strong crosswind here (guess B-52s had no problem), and you will use up a lot of the 12000 foot runway to make a powered landing and stop. Then have to taxi forever to get to GA ramp (very few exits off the runway).

      • Mike says:

        Going back a long way (1958) but we had F102′s at KI Sawyer when I was stationed there. Also spent a couple of years at Kinross AFB in the late 1950′s. Lovely place…except in the winter when the lake effect snows came in. I don’t remember much about the cross winds but I do remember when the (Sawyer) airport got fogged in and we had planes landing all over the UP. I think at least one ran off the runway and another couldn’t find the way back to the tarmac.

  2. Paul Richardson says:

    What does ORM mean?

  3. Kayak Jack says:

    We’re working for a crosswind runway where I hangar in Mason MI (KTEW). It will be a good benefit. I figure I’d do about 50 more takeoffs and landings a year with a properly constructed airfield – and be safer in the process.

  4. Hew says:

    I flew a Helio Courier for many years. This is an interesting tail dragger in that the main undercarriage is mounted well forward of the C of G which gives great braking / soft ground performance without the threat of nosing over. The down-side is that the tail has a very long leverage arm and, in spite of a tall fin, one often ran out of rudder in a cross wind. The whole issue was exaggerated when landing or taking off on a sealed surface as the tyres tend to grip.
    The solution in the Helio. Land or take-off across the strip. It had a minimum flight speed of 27kts so in a 30kt cross wind you were flying as soon as the throttle met the firewall! This manoeuvre is more alarming for the man in the tower than the pilot.

    • mike strzok says:

      In addition to cross strip operations in strong cross winds; airplanes with less capability than STOL airplanes can operate by starting TO/landing roll on the upwind side of the runway angling toward the downwind side and making a arc that ends up coming back to the upwind side. I used this technique teaching students in SE Alaska where the wind blows sometimes. I also see reluctance from some pilots to use all the control movement available when needed. Move rudder and aileron controls to their stops if needed as well as judicious directional braking. Measure the angle from the outboard gear to the wingtip on the same side to get an idea of how far that wing can go down before dragging the tip. If you have a small enough airplane, jack up one gear until the opposite wingtip touches the ground and get into the cockpit to appreciate what that angle is. Many pilots I have flown with have no idea of the airplanes capability.

  5. Dave Parsley says:

    Last week Mac managed to spin an entire article out of people using the word “tarmac” instead of “asphalt”.

    This week he refers us to “U-Tube”…

    • Robert Braid says:

      So what exactly is your point?

      • Bob says:

        It’s “YouTube” not “U-Tube” (but it appears to have been corrected)

        If you are pedantic about something, better get everything else right or you will be called out by someone else when you mess up.

  6. Cary Alburn says:

    That the Baron’s demonstrated crosswind capability may be only 22 knots does not mean that a 22 knot crosswind is its limit–it just means that was what the test pilot at the factory did on the certification test flight. Almost all airplanes’ crosswind limits are much higher than the demonstrated crosswind capability published in their POHs or owners manuals. The real limiting factor is the skill of the pilot.

    I have certainly landed many different 172s and 182s (which have a 15-17 knot demonstrated crosswind capability depending on model) at much higher crosswind components, as high as 30 knots. Given a crosswind runway more closely aligned with the wind, however, I normally choose not to do it. But flying into one lung airstrips knowing that I can handle a whale of a lot more than the book says has been demonstrated is comforting, especially in this part of the country where the next nearest airport may be 50 or 60 miles away.

    Like anything else in aviation, the pilot has to weigh the risks and decide if he/she is prepared to accept the increased risk of a stiff crosswind vs. an extended taxi, which in some cases, such as quartering tail winds, may in itself amount to a significant risk.

    I don’t always agree with Mac, but in this situation, I’m not prepared to criticize him. Given the exact same circumstances, I probably would have taken 36, but I could have taken 27 as well.

    Cary

  7. Dov Elyada says:

    Here’s a way to estimate the crosswind component w/o resort to tables or calculators:

    Just IMAGINE — see it as if before your eyes — a circle of radius 100, you at the center and a ray coming at you from the wind direction. The crosswind PERCENTAGE is the imagined perpendicular distance from the ray/circle intersection to your flight path. Can you SEE it? I know I can. (Mac’s calculation turned out too small because he used, in effect, a square diamond shape instead of the circle.)

    And, by the way, after more than a century, couldn’t aviation come up with a more up-to-date wind indicator that the archaic, Wright brothers’ era improvisation, windsock?

    • Kayak Jack says:

      Windsocks – I think that a simple streamer (the simpler the better) is a reliable way to indicate wind. We can’t have a guy out there tending a smokey fire to provide smoke.

      My difficulty with windsocks is that they bleach out, are no longer orange, and are hard to see from the air. Sometimes I can see the pole from the air, but no sock. Once I’m on the ground, and taxi past it, there it is – with an orange underbelly and a dingy, whitish upper surface. Camouflaged wind socks are no help at all.

  8. Gilbert says:

    If you fly a heavy twin with high wing loading that lands at 80mph you probably don’t worry about crosswinds or need crosswind runways.

    Flying a light wing loaded taildragger that lands at 52 mph I do worry about crosswinds. Yes I can land in a 30 knot cross wind and have done it but I sure don’t do it if there is an airport close with a runway into the wind.

  9. JOHN DENNEHEY says:

    I FLEW DC3 FOR NORTH CENTRAL 1958 TO 1963 .WE NEVER MISSED A STOP
    DUE TO CROSS WINDS.
    JOHN DENNEHEY

  10. Your name Dick Kaiser says:

    I’d always prefer a runway aligned as close as possible to the current wind and put up with the few extra minutes and pounds of fuel consumed taxiing–might just save a few $$ and embarrassment. Never hurry; you just get some place you didn’t want to be sooner. Kaise

  11. Jan Miedema says:

    Cessna for example in their C152/C172 Pilot Operating Handbooks state explicitly in the definition of maximum demonstrated crosswind that it is – well – the maximum crosswind demonstrated by the testpilot, and they explicitly add that it is not to be considered a limitation. Note that other than operational limitations like V_a, V_no, V_ne, g-load factors, RPMs etc, the maximum demonstrated crosswind is NOT mentioned in the LIMITATIONS section.

    I would largely agree with Cary that the real limit is the skill of the pilot, let´s say in terms of his good judgement, of the situation as well as of his own capabilities, where experience is important and recent experience often more than overall cumulative experience.

    I would recommend to use circumstances with stronger crosswinds to go up with an experienced and skillfull instructor to open your crosswind envelope and thus in a responsible way extend your capabilities without taking on additional risk.

    And remember, when you are in an approach for a crosswind landing and you don´t like it, GO AROUND, for either another try or to find another runway or other airport.

    One option is to just dedicate one approach to a low fly-by, set up for your chosen landing configuration (recommended flapless with the stronger crosswinds when runway length permits), set up on final for the low wing method (ailerons into wind and off-wind rudder), and fly down the runway three wheels high, to see if you manage to follow the centreline and keep the heading aligned at the same time, with an airspeed and the required power to maintain it, corresponding to approximately level attitude. Judge the situation and your capabilities to handle it: wind gusts and shifts or not, can you handle them or not, how much more rudder deflection do you have remaining, what bank angle do you need wing-low, what margin wing tip to runway imagining you were three wheels lower, etc.

    Remember for the touchdown you need a lower airspeed for the nosewheel to remain above the upwind mainwheel (limiting this post to tri-cycle gear), and less propwash over the tail, requiring more rudder than in the fly-by.

    Observe, evaluate, and decide.

    Happy landings.

    Jan Miedema

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