Taking off and landing in curtain crosswind conditions can be very dangerous. If a strong enough crosswind is encountered the airplane is unable to prevent a sideways drift which results in a hazardous landing condition, especially at airports with parallel runways.
The maximum demonstrated crosswind component is published in the aircrafts POH.
For an example a Cessna 172N maximum demonstrated crosswind component is 15 knots, as listed in Section 4 of the POH under Speeds for Normal Operation.
Whereas, a PA-28R-201 Piper Arrow has a maximum demonstrated crosswind component of 17 knots, per its POH in Section 2 under Limitations.
The crosswind and headwind component chart allows for figuring the headwind and crosswind component for any given wind direction and velocity during your preflight. If the crosswind and velocity exceed the aircraft max demonstrated component, either use a different runway for takeoff or landing, or if need be, divert.
A couple of example questions that are similar to the actual FAA knowledge test questions.
1 Test Question:
What is the headwind component for a landing on Runway 18 if the tower reports the wind as 220° at 30 knots?
A. 19 Knots
B. 23 knots
C. 26 Knots
Answer Explanation:
Answer is 23 Knots.
The direction for runway 18 is 180°. The wind is from 220° at 30 knots. 220 - 180 = 40° crosswind. Move down the 40° line until it intersects the 30-wind velocity arc. Move straight left to find a 23-knot headwind component. Don’t get this confused, key is we are looking for the headwind.
2 Test Question:
What is the crosswind component for a landing on Runway 18 if the tower reports the wind as 220° at 30 knots?
A. 19 Knots
B. 23 Knots
C. 30 Knots
Answer Explanation:
Answer is 19 Knots.
Calculate the angle between the wind and the runway 220 - 180 = 40°. Next, find the intersection of the 40° line and the 30-knot wind velocity arc. Then, proceed down to determine a crosswind component of 19 knots. Key is we are looking for the crosswind.
References:
PHAK Ch. 11
Aircraft Pilot Operating Handbook (POH)
Chart found in Knowledge Test Supplement Book
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