Estimating Crosswind Landings

Seasonal changes are often windy times. A look at the recent FAA preliminary accident report records reflects this, with a big increase in Loss of Directional Control (LODC) crashes during takeoff and, especially, during landing (LODC-L).1 LODC-L events usually have four things in common:

1. There are no injuries. LODC-L events are low-speed impacts; it’s rare when anyone gets hurt.
2. Airplane damage is usually substantial. Bent wing tips, “wiped out” (collapsed) landing gear both in fixed and retractable gear airplanes, and propeller strikes (which require propeller replacement or repair and a complete engine tear-down inspection and reassembly) are common elements of the LODC-L impact
3. Because of the type of damage involved, the cost of repairs is usually enough to “total” an airplane, or at the very least, to require costly repairs and long down-time.
4. In the vast majority of LODC-L events, the computed crosswind component is less than 10 knots.

10 knots? My research into LODC-L runway excursions shows that the reported wind is rarely very strong. It’s almost never near the published Maximum Demonstrated Crosswind speed for the airplane. Maybe when the wind is quite strong we realize we must be on top of our game and give crosswinds the attention they need. Perhaps we choose to land on another runway, or even go somewhere else entirely. When the winds are lighter, however, we might not be giving the crosswinds the attention we should.

There is a limit to an airplane’s control authority that determines the maximum speed at which maintaining runway alignment is physically possible. This is not the maximum crosswind figure published in the Pilot’s Operating Handbook; the POH merely lists the maximum crosswind component that was demonstrated during the airplane’s certification process. The “ultimate crosswind component” would depend on a lot of factors, including engine power, runway coefficient of friction, the quality of the airplane’s tires, and whether the crosswind was coming from the left or the right – so many variables that publishing a precise figure would be nearly impossible, and be essentially useless to a pilot.

But history shows the maximum crosswind component, that is, the threshold of loss of control, is not determined by the airplane. It is determined by the abilities and attention of the pilot. One of the factors in LODC-L mishaps, in my opinion, is that pilots don’t think very much about crosswinds when preparing to land. We listen to the AWOS or ASOS to determine the runway to use, choose the same runway as other traffic in the pattern, or accept the runway assigned by a control tower. Once the runway-in-use decision is made (or made for us), we tend to mentally discard the wind information. Most pilot training conditions us to consider the crosswind component for takeoff. When it comes to crosswinds for landing, however, we often take whatever we get.

This lack of focus may drive so many airplanes off the sides of the runway, often to never fly again. We just aren’t thinking about crosswinds. Part of the reason may be that not everyone is a whiz at doing math in their head while flying an airplane. But it doesn’t take the power of an E6B to estimate the crosswind component for a runway you’re considering using. You can get close enough, while erring on the conservative side for purposes of in-flight estimation, by thinking about 1/3, 2/3, and 100%. 

There are some simple methods that can be used to estimate crosswinds. Here is the process I use and teach:

When you listen to ATIS, AWOS, or ASOS, determine the angle between the runway heading and the reported wind.

If the difference is 20° or less,assume the crosswind component is1/3 of the reported wind speed.This is very conservative when the angle is smaller within this range, and closer to correct at the 20° angular difference point.

If the difference between runway heading and wind direction is more than 20° but less than 45°,assume the crosswind component is 2/3 of the reported wind speed.Again, this is conservative at the lower end of this range but closer to accurate at the 45° point.

If the difference between runway heading and the reported wind is45° to 90°,assume the crosswind component equals 100% of the reported wind speed.

Once you have estimated the crosswind component, ask yourself honestly if you’re well-rested and current enough on crosswinds to land with the estimated crosswind component. If “yes,” prepare for a crosswind landing using appropriate control inputs. If honest reflection indicates you’re not ready to handle that crosswind on that day don’t even try. Pick (or ask the tower for) another runway with a crosswind you can honestly accept, if one exists. If not, divert to another airport with crosswinds that do not exceed your personal limitations at that particular time.

You may use some other method to estimate crosswinds for landing. I expect, however, that many pilots use no landing crosswind estimation system at all. If you don’t estimate crosswinds for every landing you are a LOCD-L event waiting to happen. You can fix that easily, and avoid adding to the long list of LODC-L mishaps, by remembering 1/3, 2/3 and 100%.

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¹ Presentation by Dr. Earl Weener, Member, NTSB, at the NBAA Single-Pilot Safety Stand-Down, Las Vegas, NV November 16, 2015. http://www.ntsb.gov/news/speeches/eweener/pages/default.aspx

^{Holder of an ATP certificate with instructor, CFII and MEI ratings and a Masters Degree in Aviation Safety, 2010 National FAA Safety Team Representative of the Year, 2015 Inductee into the NAFI Hall of Fame and 2008 FAA Central Region CFI of the Year, three-time Master CFI Thomas P. Turner has been Lead Instructor for Bonanza pilot training program at the Beechcraft factory; production test pilot for engine modifications; aviation insurance underwriter; corporate pilot and safety expert; Captain in the United States Air Force; and contract course developer for Embry-Riddle Aeronautical University. He now directs the education and safety arm of a 9000-member pilots’ organization. With over 4000 hours logged, including more than 2500 as an instructor, Tom writes, lectures and instructs extensively from his home at THE AIR CAPITAL--Wichita, Kansas. Subscribe to Tom’s free FLYING LESSONS Weekly e-newsletter at http://mastery-flight-training.com/}