Crosswind Components

drunkenbeagle said:
My mistake. I swear my CFI told me they were in true north :) Curious, how does flight watch or Unicom generally report, since they are probably looking at the Metars (which should also be true for surface observations, correct?)
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Flight Watch is probably looking at METARS and Unicom is usually looking at the wind indications, so it should be magnetic.

The way I always remembered it was if it's somebody on the ground where I'm going, it is supposed to be magnetic. A forecast is true. A METAR should be magnetic. Too late to look it up but I'm sure people will be all over this.:D
 
I used to spend time (and valuable brain cells) trying to memorize all the details but for the most part common sense seems to be at the heart of things. Approaching a field, the runway is a magnetic heading (+/- the up to 5 degree difference), your DG is set to the compass which is magnetic and weather is reported in magnetic. One shouldn't have to be thinking about converting true to magnetic on top of increased workload.
 
A sidebar... something i taught my students when I was instructing years ago. Those x-wind component charts are great for pre-flight, etc. But, if you're actually in the airplane and don't have time to reference the crosswind component chart for whatever reason just use your watch to give you a good idea of what your xwind component is.

ex. you have a 30 degree x-wind @ 30 knots. Take a look at a watch. 30 minutes is half way around the watch so use half of 30= 15 knot crosswind component.

ex. gusting 45 knots and 20 degrees off the nose. 20 minutes on your watch is 1/3 of the way around... 1/3 of 45 is 15 knots. xwind component of 15.

Any greater than 60 degrees just say it's the reported wind.

This is by no means perfect... but it will get you within a few knots of the x-wind component chart in the POH in normal situations. It's also something to keep in mind in an emergency when you need to get on the ground quick and don't have time to reference any chart.
 
meritflyer said:
Until you bend a wing up and 91.13 is pulled out and thrown at you.
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Common sense here is appropriate. If you're flying in gale force winds(crosswinds) and are a private pilot, I don't think it would matter what the demonstrated component was.

Remember that crosswind components are determined with no exceptional pilot ability. We're not talking test pilot greasers, just normal pilots making a crosswind landing. If it's within the pilots ability, you have other problems if you bend the wing.
 
drunkenbeagle said:
I'm pretty sure METARs are always true.
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Printed, yes, but if you hear it over FAA radio, it's magnetic, according to the AIM:

Section 7-1-12, Weather Observing Programs

[...]

Wind direction broadcast over FAA radios is in reference to magnetic north.
​
 
Maurus said:
Ever see a headwind/xwind component chart before?

windcomponent.jpg
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And I just try to rough it with 30deg being half, 45 deg being 2/3rds of the wind and anything more than that.. full value.
 
I landed a 172 one time at the big airport with a crosswind and the tower guy said "nice landing........all of them". :laff:
 
tgrayson said:
Printed, yes, but if you hear it over FAA radio, it's magnetic, according to the AIM:

Section 7-1-12, Weather Observing Programs

[...]

Wind direction broadcast over FAA radios is in reference to magnetic north.
​
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This is how one of my former instructors taught it to me, and it stuck enough that I used it with my students: when it comes to winds, if you see it, it's true, if you hear it, it's not...it's magnetic. I think there may be some obscure exception somewhere, but for the stuff you use most often, this works.
 
gomntwins said:
A sidebar... something i taught my students when I was instructing years ago. Those x-wind component charts are great for pre-flight, etc. But, if you're actually in the airplane and don't have time to reference the crosswind component chart for whatever reason just use your watch to give you a good idea of what your xwind component is.

ex. you have a 30 degree x-wind @ 30 knots. Take a look at a watch. 30 minutes is half way around the watch so use half of 30= 15 knot crosswind component.

ex. gusting 45 knots and 20 degrees off the nose. 20 minutes on your watch is 1/3 of the way around... 1/3 of 45 is 15 knots. xwind component of 15.

Any greater than 60 degrees just say it's the reported wind.

This is by no means perfect... but it will get you within a few knots of the x-wind component chart in the POH in normal situations. It's also something to keep in mind in an emergency when you need to get on the ground quick and don't have time to reference any chart.
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Thanks for that helpful hint. I'll throw that in my 'bag o' trix' ;)

I always needed to bust out the chart.
 
gomntwins said:
A sidebar... something i taught my students when I was instructing years ago. Those x-wind component charts are great for pre-flight, etc. But, if you're actually in the airplane and don't have time to reference the crosswind component chart for whatever reason just use your watch to give you a good idea of what your xwind component is.

ex. you have a 30 degree x-wind @ 30 knots. Take a look at a watch. 30 minutes is half way around the watch so use half of 30= 15 knot crosswind component.

ex. gusting 45 knots and 20 degrees off the nose. 20 minutes on your watch is 1/3 of the way around... 1/3 of 45 is 15 knots. xwind component of 15.

Any greater than 60 degrees just say it's the reported wind.

This is by no means perfect... but it will get you within a few knots of the x-wind component chart in the POH in normal situations. It's also something to keep in mind in an emergency when you need to get on the ground quick and don't have time to reference any chart.
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That is a very good mental formula to relate to students. I think I will steal it if you don't mind.

I teach a sine table but it normally goes in one ear and out the other, thus why I like your explanation more for students.

Sine table:

if angle between runway and wind direction <40 degrees then:
Angle/60 = sine value

if angle between runway and wind direction >40 degrees then:
Angle+25 = sine value

Examples:
Angle 20 = 20/60 = .33 (1/3)
Angle 30 = 30/60 = .50 (1/2)
Angle 40 = 40/60 = .66 (2/3)
Angle 50 = 50+25 = .75 (3/4)
Angle 60 = 60+25 = .85 (whatever fraction this is)

Now for headwind component you do the same thing but you take 90-the angle between the wind and runway, which in turn gives you the cosine.
[/dorkiness]
 
AirmetTango said:
when it comes to winds, if you see it, it's true, if you hear it, it's not...it's magnetic. I think there may be some obscure exception somewhere, but for the stuff you use most often, this works.
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PIREPS are always converted to true as far as I know. (correct me if I'm wrong - there must be a controller who knows for sure).
 
I use the "6 Rules of Thumb"

Wind direction and Heading difference: amount of total wind speed as xwind component
10 degrees: 1/6
20 degrees: 2/6
30 degrees: 3/6
40 degrees: 4/6
50 degrees: 5/6
60 degrees or more: assume 100%

Makes it MUCH easier on the fly... Either that or get a little calculator and clip it to your kneeboard...
 
Dan64456 said:
I use the "6 Rules of Thumb"

Wind direction and Heading difference: amount of total wind speed as xwind component
10 degrees: 1/6
20 degrees: 2/6
30 degrees: 3/6
40 degrees: 4/6
50 degrees: 5/6
60 degrees: assume 100%
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why not just learn the trig???
Why you start pulling 2 gees at 60 aob 1.4 at 45??
sin of 30 is .5 (square root of 1/2)
sin of 45 is .707 (square root of 2 /2)
sin of 60 is .866 (square root of 3/2)
cos of 30 is .866 (square root of 3/2)
cos of 45 is .707 (square root of 2 /2)
cos of 60 is .5(square root of 1/2)

I just looove trying to explain to CFI know it all that the FAA 1/60 rule is really the sin of 1 degree rule that is an approximation that means nothing after about 5 degrees.
 
granlistillo said:
why not just learn the trig???
Why you start pulling 2 gees at 60 aob 1.4 at 45??
sin of 30 is .5 (square root of 1/2)
sin of 45 is .707 (square root of 2 /2)
sin of 60 is .866 (square root of 3/2)
cos of 30 is .866 (square root of 3/2)
cos of 45 is .707 (square root of 2 /2)
cos of 60 is .5(square root of 1/2)

I just looove trying to explain to CFI know it all that the FAA 1/60 rule is really the sin of 1 degree rule that is an approximation that means nothing after about 5 degrees.
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Because flying is much more interesting to me... lol
 
Dan64456 said:
Because flying is much more interesting to me... lol
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I hear ya brotha. I leave my calculator at home when relaxing around the patch. My comment was directed at fellow airline pilots and those that want to discuss the professional side of aviation. It was specifically not directed at c172 private pilots in the peanut gallery lol. If you have anything other to add besides your ignorance, please opine.
 
granlistillo said:
I hear ya brotha. I leave my calculator at home when relaxing around the patch. My comment was directed at fellow airline pilots and those that want to discuss the professional side of aviation. It was specifically not directed at c172 private pilots in the peanut gallery lol. If you have anything other to add besides your ignorance, please opine.
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Go get laid... There's my opinion.
 
Why? I get's mine and math comes pretty naturally to me. Of course, once you figure out that everything's "base 10"!
 
And I'm sure "professional" airline pilots sit there with calculators after getting the winds to figure out the crosswind component to the exact decimal.
 
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