Calculating the crosswinds is important when taking off and landing. This is especially true when picking the appropriate runway if more than one runway exists at a particular airport.
The crosswind component chart and the max demonstrated crosswind component of any aircraft can be found in the POH.
For an example in the POH of a Piper Cherokee PA-28-140, the max demonstrated crosswind component is 17 knots. Anything greater than 17 knots the airplane can not maintain centerline down the runway, even with full counter deflection of the flight controls to correct the sideways drift.
How to calculate crosswind and headwinds
First we need to know the wind and runway information give to us by either the tower or the ATIS.
For this we will use the following information:
Winds are 250° at 20 knots, runway 27 is in use.
1. Next we need to find the difference between the wind direction and runway in use. 270 - 250 = 20° (A).
2. Find the wind speed of 20 knots on the wind velocity arc (B).
3. From (B) draw a line straight down to find the crosswind of 7 knots (C). To find the headwind draw a horizonal line from (B) to the headwind speed, 19 knots (D).
A couple of written test question we may see
Written Test Question 1:
What is the crosswind component for a landing on Runway 18 if the tower reports the wind as 220° at 30 knots?
220 – 180 = 40
40° down to 30° arc, then straight down to 19 knots.
Answer: is 19 knots
Written Test Question 2:
What is the headwind component for a landing on Runway 18 if the tower reports the wind as 220° at 30 knots?
220 – 180 = 40
30° arc, then straight across to 23 knots
Answer: is 23 knots
References:
PHAK Ch. 11
Aircraft POH charts
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