A trick pilots use to quickly calculate crosswind

The other day I was teaching a student on flight simulator. After he picked up the ATIS I asked him what the crosswind was going to be for take-off. I wanted him to start thinking about the information he had in his hands, and not making a habit of listening to the ATIS just something that he was doing simply because he was going through the motions. He responds by pulling out his calculator and doing the accurate measurement. I asked him if he carried a calculator in his real world PPL lessons, and he admitted that he didn't. So how was he supposed to calculate crosswind? This article outlines the simple trick of doing this.


Once the wind direction has been received (i.e via the ATIS), the pilot calculates the angle difference between the runway heading and wind direction. The pilot then imagines the minute hand on a clock face indicating on that number of minutes. For example, if the difference is 15 degrees, the pilot imagines the hand pointing at the 3 on the clockface. The amount that the minute hand has travelled around the clock relative to a full rotation is the component to be applied to the full wind component in order to calculate the crosswind component.


For example, if the wind is coming from 330 degrees at 10kt, and the runway in use was runway 36, the crosswind angle would be 30 degrees (the smallest angle between the wind direction and runway heading). The minute hand would have travelled halfway around the cock in order to reach the 30 minutes position, the number 6 on the clockface. Therefore, the crosswind component is 5kt.


It's a simple and quick to use rule. 15 degrees? use a quarter. 40 degrees? Use two thirds.


What if the angle is greater than 60 degrees? Simply use the full component. For example, if the wind is coming form 070 at 10 knots and we're departing runway 36, the angle would be 70 degrees, which is greater than 60, so we would use the full wind component of 10 knots of the purpose of our caclulations. If you do the calculation the traditional way, (wind component x sin(angle)) the actual answer is 9.4 knots, which is pretty close.

And that's it for calculating crosswinds quickly in your head. If you want guidance with this method and more, you can book a lesson with one of our instructors on the ANC Academy website.

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