Introduction: How to Find a Crosswind Component
Before a flight, it is important to be familiar with all current weather information. One piece in particular that must be familiarized is the headwind and crosswind component, because this effects which runway is being used for takeoffs and landings, as well as how you will complete the takeoff or landing, and most importantly, whether or not it is safe to takeoff and land. This Instructable will walk you through how to determine which runway to takeoff and land on, as well as how to find the crosswind and headwind components. The materials required to find these components are a chart supplement or airport diagram, and a crosswind chart which can be found in an aircraft's information manual, or pilot's operating handbook.
Step 1: Determine the Runway Numbers
Looking at the airport diagram in the chart supplement, find the numbers on the end of each runway.
In the example shown above, these numbers are 14, 19, 1, and 32.
Step 2: Determine the Runway Directions
Multiply the runway numbers by 10. If the number has only two digits, include a zero before the first number. These represent the directions on a 360° circle, as shown above.
In the example, the runways are 140°, 190°, 010°, and 320°.
Step 3: Choose a Runway
Now that you know your runway options, it is important to choose the runway with the strongest headwind component. Determine, based on the 360° circle, which runway is closest in direction to the wind direction given. Because the directions are on a circle, the closest runway direction to the wind could be on the opposite side of 360.
In the example, if the winds are reported at 030° at 13 knots, the closest runway is runway 1, which is pointed in the 010° direction.
Step 4: Find the Difference Between the Runway and the Wind
Subtract the smaller number from the larger number, unless crossing 360. If the wind is on one side of 360 and the runway is on the other, subtract the higher number from 360, and zero from the lower number. Then add the two numbers together to find the difference.
In the example, 030 - 010 = 20°
If looking at a runway that is 350 and wind that is 010, 360 - 350 = 10°, 030 - 0 = 30°, and 10° + 30° = 40°
Step 5: Mark the Direction and Velocity on the Chart
On the wind component chart that can be found in the plane’s information manual, follow the line that represents the difference found, and mark where it intersects with the wind speed arc.
In the example, follow the 20° line out to somewhere between the 10 and 15 knot arcs, around where 13 knots would be.
Step 6: Find the Crosswind and Headwind Component
After marking the point where the direction and velocity intersect, draw a straight line down to the bottom of the chart to determine the crosswind component, and a straight line to the left side of the chart to determine the headwind component.
In the example, the crosswind can be read around 5°, and the headwind is around 13°.