Wind direction True or Magnetic Compilation

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pstan

Pre-takeoff checklist
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May 17, 2009
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Display name:
Stan
So...how many did I get correct?

Degrees T:
SA printed out from FAA source or aviation provider
SA read to pilot from tower controller, approach controller, FSS, eg “latest actual at 1805z is …..”
Wind read off AWOS screen
TAF
Area forecast
Sigmet
Public forecasts

Degrees M:
Awos on vhf frequency
Awos via telephone
Atis on vhf
Atis via telephone
Approach ground or tower controller passes present winds

Can anyone add any more situations?

Stan
 
Winds aloft are True
 
I have lobbied Congress to make M=T, so pilots are not constantly grappling with this problem; no word back yet.
 
azure said:
Try the PA state legislature. Word has it they put it into law that pi is equal to 3.
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That does make it easier to remember. There is a small penalty on accuracy though...
 
In general, winds on the ground are magnetic and winds up in the air are true.
 
rocketflyer84 said:
In general, winds on the ground are magnetic and winds up in the air are true.
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No. ATIS is magnetic, but METARs are true. Same information.

A rule of thumb is that stuff read over the radio or with visual markings (runway numbers) are magnetic. Printed stuff is true.
 
MAKG1 said:
No. ATIS is magnetic, but METARs are true. Same information.

A rule of thumb is that stuff read over the radio or with visual markings (runway numbers) are magnetic. Printed stuff is true.
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Correct
 
Spoken: magnetic, Written: true

Find a towered Airport with an Atis you can call on the phone. Compare Metar winds to an Atis that is current at time of Metar. I think you,ll find the direction varies by the local Variation value. This demonstration works best when Variation is large enough to introduce a variance.

Exception to above rule is Pirep, I think they are published with value supplied by reporter?
 
Let'sgoflying! said:
FMS/FMC I think are always M
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Not always. For at least the enroute phase:

The Rockwell Collins FMS 6000/61000 series is degrees true
The UASC UNS 1C and 1E are degrees true as well, I presume the whole UNS series is.

Having said that, the wind vector on our PL 21 display is converted to degrees magnetic, which makes sense because the heading and track displayed is in degrees too.
 
"A rule of thumb is that stuff read over the radio or with visual markings (runway numbers) are magnetic. Printed stuff is true."

"Spoken = Magnetic"

Both the above not necessarily true (yes, I realize it's a rule of thumb, never the less I'm pointing out a situation where the rule is incorrect). If FSS or ATC (eg tower) reads you an SA, the wind will still be in true. However if a controller tells you the present winds, they will be in magnetic
 
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