Upon reaching land it can be difficult to quickly calculate the crosswind component. There are 2 quick methods that I know of to be able to do this and when you understand them, choose the one that suits you best.
The first is known as the clock code and with it it is assumed that any wind that is more than 60 degrees off the runway heading is a full force crosswind. So if you land on runway 27, which is 270 degrees north, if the wind direction is less than 210 or greater than 330 degrees, whatever the strength, it’s considered a full crosswind. So if the wind is 200 to 15 knots, then it’s a 15 knot crosswind.
Now, to calculate how much crosswind there is between these 60 degrees on either side of the runway heading, imagine that the number of degrees off course are the numbers of minutes around a clock face. Then imagine how far away the clock face is, and that ratio around the clock face is the ratio of the force of the wind.
So if the wind is 20 degrees off course, say for example 290 at 30 knots, then 20 minutes is one third of the way around the clock face, so the crosswind component is one third of 30 knots, which is 10 knots.
If the runway is 03, which is 030 degrees, and the wind is 070 at 20 knots, this is 40 degrees off the runway heading, and 40 minutes around the clock face is almost three-quarters of the way around the clock face. clock face, so the cross wind is three quarters of 20 or 15 knots.
Since the wind is constantly varying in strength and direction, you don’t need to be very precise with your calculation. If the wind is about 30 degrees off, it is half as strong, so about half of the wind’s strength is the crosswind component. 45 degrees less is 3/4 of the strength of the wind and 60 degrees or more maximum strength.
Another easy way to calculate crosswind and headwind is to use this simple mathematical formula.
For the calculation of the crosswind. If the wind is 30 degrees off the nose, it’s .5 the strength of the wind, 45 degrees. 7 the force of the wind, 60 degrees. This also applies to cross-country flights and to calculate the crosswind component when landing.
If, for example, when you come in to land the wind is 60 degrees off the runway heading, it’s .9 times the wind strength, so using simple arithmetic in a 20 knot wind, just multiply 9 by 2, which It’s 18 knots. For a 30 knot wind and 45 degrees off the runway heading, the calculation is 3 X 7, which is a crosswind component of 21. If like me you learned your multiplication tables as a kid, this is easy.
If you reverse the formula, you can also use it to calculate the headwind or tailwind component. So if the wind is straight at you it is at full force, if it is at 30 degrees it is 0.9 full force, at 45 degrees it is 0.7 full force and if it is at 60 degrees it will be the half his strength.
If it is at 90 degrees, then there is no headwind or tailwind component. However, keep in mind that any strong wind will affect the aircraft by drifting and becoming wind, which will mean it has to fly a longer route than a straight line, so it will always slow you down. The stronger the wind, the longer your journey will take.
If the wind is behind you, then the same ratios can be applied to calculate the tailwind component, so if it’s 30 degrees from your tail, it’s 0.9 of the wind force and so on.
To calculate a yaw, you can apply this percentage to your airspeed to get your ground speed, and then to calculate drift, interpolate the following formula as well. The formula is that at an airspeed of 120 knots, half of the crosswind component is drift. But most light aircraft fly a little slower than this, so the drift is greater. So if you are flying at 90 knots, your drift would be 25% more than half the drift, since 90 knots is 75% of 120 knots, so you need to add the difference to the drift.
This method can be used to quickly calculate your course and ground speed if you need to deviate, or if you want to check your calculations after using a computer to plan your trip.