X-Wind Calculator

Salkadi

Salkadi

Well-Known Member
Just wondering what everybody else uses to check cross winds. I have used windwiz.org in the past, but it is now a subscription website, so that's no bueno. Aeroplanner seems to be pretty popular though.
 
I used windwiz before too. I've started using the Airport Summary ---> TAF --->Wind Breakdown on Flight Explorer if you have that option...
 
windcomponent.jpg


Print that out. It even works without batteries. Use it enough and you can get a good enough estimate by visualizing that in your head.
 
To get a rough idea of the crosswind, there's a pretty easy formula I use:

((Degrees difference between wind and runway/100) + 0.2) x Wind Speed = Crosswind

I know, I said it was easy right? But after you get the hang of it, it really is.

An example: Winds 320 at 14, landing on Runway 1

Difference in degrees = 50
Divided by 100 (same as putting a decimal in front the number) = 0.5
Add 0.2 = 0.7
Multiplied by wind speed of 14 = about 10 knots crosswind

Using the chart posted above, the exact answer is probably closer to 11, but again this formula is just a quick way to figure a close approximation.
 
In theory, it doesn't become an issue until you are approaching aircraft limits and it is 45 degrees or more from the runway heading. Of course I could just be lazy as well. :D
 
I learned the mental math from the Navy and it is very precise (for mental math) because we used the math the place warheads on foreheads but I have to admit the angle/100+.2 is very easy and perfectly acceptable accuracy good for this purpose.
 
F9DXER said:
In theory, it doesn't become an issue until you are approaching aircraft limits and it is 45 degrees or more from the runway heading. Of course I could just be lazy as well. :D
Click to expand...

Had one not that long ago that couldn't depart because the wind exceeded limits...how often does that come up for u guys? For me, only once in my 6 months at Ryan.
 
F9DXER said:
In theory, it doesn't become an issue until you are approaching aircraft limits and it is 45 degrees or more from the runway heading. Of course I could just be lazy as well. :D
Click to expand...

Heh. Three words: Winter in Keflavic. I remember last winter running into a few times where I couldn't use KEF as an ETOPS alternate simply because of the winds, which seemed to routinely forecast 60 gusts to 75.
 
Wind Angle + 20 = percentage of total wind.
Runway 22 = 220. Wind direction 250 = 30 degrees difference. Add 20 = 50 % of total wind is crosswind.
Same formula mentioned above. But no decimals!


Another way to think of it is look at your watch (Not a digital watch). Is the wind 30 degrees of the runway? If so look at 30 minutes. Its Halfway around the clock, therefore its half the crosswind. Is the wind 45 degrees off the runway? If so, look at your clock. 45 minutes is 3/4 the way around the clock, therefore the crosswind is 3/4 of the total wind velocity. Works for all practicable purposes.
 
pljenkins said:
Heh. Three words: Winter in Keflavic. I remember last winter running into a few times where I couldn't use KEF as an ETOPS alternate simply because of the winds, which seemed to routinely forecast 60 gusts to 75.
Click to expand...

Exactly what I was thinking. winds in North Atlantic stations get out of control.
 
Remember high school trigonometry guys?? The sine of 30 degress = .5. The sine of 90 degrees = 1, so on and so forth.

If the sine of 30 degrees is .5, any angular difference of 30 degrees between the runway and the wind direction will yield 50% of the total wind component as crosswind. Obviously, if the sine of 90 =1, 100% of that total wind is crosswind. A good rule is anything over 30 degrees angular difference is at least half the total wind speed.

To estimate the percentage of any crosswind component quickly, take the sine of the angular difference between the wind and the runway. Multiply the percentage by the total wind speed and that's the crosswind.

It works very fast and it's very accurate.

Ugh, math!!?! But wait...I know it may seem tedious at first to relearn the sine values for degree values (10, 20, 30, 40, etc), but once you do it helps you move through this stuff very quickly and precisely. I use it mentally in the airplane, and it's one of those very handy rules of thumb that helps to salvage a good landing from the clutches of a bad landing when the winds change or you get a last minute runway change and things become busy.

sin0 = 0
sin10 = .173 (~20%)
sin20 = .342 (~40%)
sin30 = .5 (50%)
sin40 = .643 (~70%)
sin50 = .766 (~80%)
sin60 = .866 (~90%)
sin70 = .933 (~100%)
sin80 = .984 (~100%)
sin90 = 1 (100%)
 
ljg said:
Remember high school trigonometry guys?? The sine of 30 degress = .5. The sine of 90 degrees = 1, so on and so forth.

If the sine of 30 degrees is .5, any angular difference of 30 degrees between the runway and the wind direction will yield 50% of the total wind component as crosswind. Obviously, if the sine of 90 =1, 100% of that total wind is crosswind. A good rule is anything over 30 degrees angular difference is at least half the total wind speed.

To estimate the percentage of any crosswind component quickly, take the sine of the angular difference between the wind and the runway. Multiply the percentage by the total wind speed and that's the crosswind.

It works very fast and it's very accurate.

Ugh, math!!?! But wait...I know it may seem tedious at first to relearn the sine values for degree values (10, 20, 30, 40, etc), but once you do it helps you move through this stuff very quickly and precisely. I use it mentally in the airplane, and it's one of those very handy rules of thumb that helps to salvage a good landing from the clutches of a bad landing when the winds change or you get a last minute runway change and things become busy.

sin0 = 0
sin10 = .173 (~20%)
sin20 = .342 (~40%)
sin30 = .5 (50%)
sin40 = .643 (~70%)
sin50 = .766 (~80%)
sin60 = .866 (~90%)
sin70 = .933 (~100%)
sin80 = .984 (~100%)
sin90 = 1 (100%)
Click to expand...


THIS.

A quick switch to COS and you have a handy headwind calculator too!
 
unclenobby said:
This is the easiest way.

30 degrees xwind = 50% component
45 degrees = 75%
60 degrees just consider 100%.
Click to expand...
Agreed.
To expound on this:
10 degrees 1/6
20 degrees 1/3
30 degrees 1/2
40 degrees 2/3
50 degrees 3/4
60 degrees plus = basically 100%
 
You must log in or register to reply here.
Back
Top