Charting The Wind

Pilots' inability to cope with wind is a leading cause of accidents. Misaligning the aircraft on takeoff or landing usually means an off-runway excursion. Props are dinged, nosewheels destroyed, wingtips crumpled, and occasionally an aircraft is totaled. Fortunately, most of the mayhem results in little or no injury to the occupants. But it would save the industry millions of dollars, create lower insurance rates, and preserve hundreds of aircraft if pilots handled the crosswind component with a bit more finesse.

As with most aircraft performance parameters, there is a number to guide us. The manufacturer provides a demonstrated crosswind component in the normal operating section of the pilot's operating handbook (POH). This is not the maximum side wind that the aircraft can theoretically handle. It is the most wind that the test pilots actually experienced while testing the aircraft for certification. The numbers are usually fairly high. For example, the Cessna Turbo 210 was tested to land safely in 21 knots of direct crosswind. For most of us, that will probably suffice on a day-to-day basis, and the majority of CFIs recommend that demonstrated crosswind be considered the aircraft's limit.

So the maximum number is known, but how can that be realistically applied on a windy day? A new private pilot and I were supposed to fly pattern practice on a blustery afternoon. Traffic was light, but sometimes there can be too much of a good thing. We needed to make a reasoned decision. A crosswind component chart is just the item for determining whether it will be an obliging day or not.

The winds were from 340 to 360 at 15 kt gusting to 23 kt. The active was Runway 30. Going into the chart with a relative wind angle ranging from 40 to 60 degrees, the steady state crosswind was between 10 to 14 kt. The cross component in gusts reached 14 to 18 kt. That was near or above the Piper Archer's demonstrated component of 17 kt.

We elected not to fly for two reasons. This pilot needed basic crosswind practice, and with the winds that high, I probably would have gotten more stick time than she would have. While I would have enjoyed the drill, that is not what instruction is all about. Second, crosswind-landing practice must be a confidence-building exercise that does not overwhelm the student. Put a pilot into a situation that is way beyond his or her capability and confidence may be undermined. For a cocky student, that may not be a bad lesson, but for most it is merely frustrating.

Many new pilots look for excuses not to fly, and we, as instructors, should move them out of their comfort zone to the next level - within limits, of course. My general, and admittedly arbitrary, guideline for crosswind neophytes is that 10 kt across the runway is plenty to get them started and perfect the technique. Then you can start to ratchet up the numbers.

If you are flying an aircraft that was built before 1975 and the demonstrated crosswind number is not readily available, use the FAA's type certification rules. All airplanes certificated since 1962 must have safe ground-handling characteristics with a 90-degree crosswind component equal to 0.2 VSO. An aircraft that stalls at 55 kt must be able to handle at least 11 kt (0.2 x 55) of crosswind. Some may be able to handle more; none will be uncontrollable with less.

You might want to copy the chart on the previous page and have your students laminate it for the flight bag. Then they can determine what is safe. It is far more accurate than guessing, and if they have a self-imposed limitation well below what the book mandates, they can easily determine if the wind is above their minimums.

With the advent of automated weather reporting (AWOS and ASOS), accurate wind information is available at more airports than ever. If pilots know how to chart the surface winds and are encouraged to practice, perhaps we can reduce the amount of recycled aluminum.

Bruce Landsberg is executive director of the AOPA Air Safety Foundation.