The crosswind component is the part of the wind blowing straight across the runway, and it is what actually challenges your landing. It depends on two things: how strong the wind is and the angle between the wind and the runway. This page shows the simple math, a fast mental shortcut, and a free calculator so you can find your crosswind and headwind components before every flight.
Part of our Navigation and Flight Planning guide. For the flying technique, see Crosswind Landings: Crab and Wing-Low.
Skip the arithmetic: PilotMall’s free online E6B flight computer has a wind side that returns your crosswind and headwind components, wind correction angle, and ground speed in seconds. It works in any browser and offline.
The formula
Crosswind and headwind components come from basic trigonometry, using the angle between the wind and the runway heading:
- Crosswind component = wind speed x sine of the angle
- Headwind component = wind speed x cosine of the angle
A wind blowing 90 degrees across the runway is all crosswind and no headwind. A wind straight down the runway is all headwind and no crosswind. Every real wind is somewhere in between.
The clock-face shortcut
You do not need a calculator in the run-up area. Treat the wind angle as minutes on a clock face, and read off the fraction of the wind that is crosswind:
| Wind angle to runway | Clock fraction | Approximate crosswind component |
|---|---|---|
| 15 degrees | 1/4 | About one quarter of the wind speed |
| 30 degrees | 1/2 | About half the wind speed |
| 45 degrees | 3/4 | About three quarters of the wind speed |
| 60 degrees | Nearly full | About 90 percent of the wind speed |
| 90 degrees | Full | Essentially all of the wind speed |
This shortcut runs a little high at 45 degrees, which is the safe direction to be wrong. When the number is close to your limit, treat the estimate as the truth and plan conservatively.
A worked example
You are landing on runway 9, which points to a heading of 090 degrees. The automated weather reports the wind from 120 degrees at 20 knots. The angle between the wind and the runway is 120 minus 90, or 30 degrees.
- Crosswind: 20 knots x sine of 30 degrees = 20 x 0.5 = 10 knots of crosswind.
- Headwind: 20 knots x cosine of 30 degrees = 20 x 0.87 = about 17 knots of headwind.
The clock-face shortcut agrees: 30 degrees is the half mark, and half of 20 is 10 knots of crosswind. Now compare that 10 knots to your airplane’s maximum demonstrated crosswind and to your own personal limit before you commit to the approach.
Maximum demonstrated crosswind and your personal limit
Every airplane’s documentation lists a maximum demonstrated crosswind component, the value a test pilot showed during certification. It is a strong reference, not a legal limit, and it says nothing about your current skill. Just as important is your own personal minimum, the crosswind you are comfortable and proficient handling today. As a student, build that limit up gradually with your instructor, and remember that choosing a different runway or a go-around is always available.
Don’t forget the gusts
When the wind is gusting, run the numbers on the gust value, not the steady wind. A report of 15 gusting 25 knots at 40 degrees off the runway gives a very different crosswind at the peak than at the lull. Plan for the gust so a strong one does not surprise you in the flare.
What you'll need
Wind and flight-planning tools from PilotMall.com.
Frequently asked questions
How do you calculate the crosswind component?
Multiply the wind speed by the sine of the angle between the wind and the runway. For a fast estimate, use the clock-face shortcut: 15 degrees is about one quarter of the wind, 30 degrees about half, 45 degrees about three quarters, and 90 degrees the full wind speed.
What is the maximum demonstrated crosswind component?
It is the crosswind a test pilot demonstrated during the airplane’s certification, listed in the pilot’s operating handbook. It is a reference value, not a legal limit, but exceeding it is a strong reason to pick another runway.
Should I use the steady wind or the gust for crosswind?
Use the gust. Planning for the peak wind means a strong gust in the flare will not exceed the number you already accepted.
What is the difference between crosswind and headwind components?
The crosswind component is the part of the wind across the runway (wind speed times the sine of the angle); the headwind component is the part down the runway (wind speed times the cosine of the angle).