Wind Direction-Magnetic or True

[jiott]

I get some conflicting answers on some of this and want to get it settled.

• Winds Aloft charts give direction as True. I'm pretty sure this is right.
• ATIS and Tower report winds as Magnetic. I'm fairly sure about this.
• AWOS and ASOS report winds as True, I think but get conflicting answers on this from CFI's and others.

Its kind of important when you are trying to pick the most favorable runway, especially here in Portland, OR where magnetic variation is 16-18 degrees.

Jim

[Pilot4Life]

AIM, Pg 7-1-30, Para 3,
"NOTE−Wind direction broadcast over FAA radios is in reference
to magnetic north."

All FAA Radios, to include TWR when you call for a wind check.

[n85ae]

I fly tailwheel, I use neither true, nor magnetic. I use windsock.

Regards,
Jeff

[Chewie]

My CFI explained it this way - It depends on where the pilot is and what resources are available to them.

On the ground = lots of charts and other resources = TRUE (METARs, TAFs, Winds Aloft)

In the airplane = a single compass? = MAGNETIC (ATIS, AWOS, Runways, ATC...)

... I think.

[SS7Flyer]

I fly tailwheel, I use neither true, nor magnetic. I use windsock.

Regards,
Jeff

Great post Jeff!

[t j]

If it's in print its true, if you hear it on the radio its magnetic, makes it simple while in the airplane.

[jiott]

I think we all agree on ATIS, tower being magnetic and printed material-winds aloft, Metars, TAF's, FA's, etc. being true. Its the ASOS/AWOS that is still in question. Even though you hear these on the radio, I believe they are taken directly from METARs which is true.

Pilot-for-Life, is an AWOS/ASOS considered an FAA radio? I see the note in AIM that you refer to, but on the next page in the decoding chart for Wind Direction & Speed it says "Direction in tens of degrees from true north(first 3 digits) ......

Jim

[Pilot4Life]

I Had Originally Posted..."AWOS/ASOS is transmitted over FAA radios. A report, i.e. METAR, generated from these "TRANSMISSIONS" will directly transfer to this "printed" report. So Magnetic to Magnetic....so, the same would be true for a report generated (or deciphered) from a Winds Aloft Chart since it's Given in True, the same would hold for that report."

This is NOT Entirely True.

After reviewing the AIM, previous posts, and re-reading my posting...

TJ is correct. Over the radio (see Description of ASOS/AWSS data outlets, 7-1-30, 3.), it's magnetic (See reference NOTE just below "(c)" ). Thus answering the question of the original post. If it's read, i.e. METAR (and I would submit "for planning purposes only"), it's True. We, as educated and experienced aviators, will ALWAYS get current weather (if available) before landing whether via Radio Broadcast ATIS/ASOS/AWOS/AWSS or the old crusty pilot on the ground tinkering with his own airplane.

oh, and of course CHECK THE WINDSOCK, High Five to Jeff!