ATIS Winds - True or Magnetic?

[Dazzler]

METARs give wind direction in relation to TRUE north.

Now, when recording ATIS, which is sourced from the METARs, is the wind direction converted to relate to MAGNETIC north instead of TRUE? This certainly would be useful seeing as Runway Designations are assigned with reference to MAGNETIC north.

[nocturnalaviator]

Originally Posted by Dazzler

METARs give wind direction in relation to TRUE north.

Now, when recording ATIS, which is sourced from the METARs, is the wind direction converted to relate to MAGNETIC north instead of TRUE? This certainly would be useful seeing as Runway Designations are assigned with reference to MAGNETIC north.

Call the tower, or go up and see them with your questions. They encourage it!

[dc3flyer]

In most places I don't think it really matters THAT much. Winds are also given 10's of degrees (such as 180 or 190) instead of actual degress (such as 183 or 187). So are a few degrees going to matter? Not to mention the winds change a little more often than the reports.

In the lower 48, what is the maximum difference, 18 degrees?

[n6149s]

When I was a developmental working on GC, I told my instructor that they were magnetic. He insisted that I was wrong, and he had been converting them 20 degrees for about 19 years. He was wrong, they are magnetic. That does help when looking down a magnetic heading of a runway.

[Greg01]

Magnetic. At BUF they take the METAR reading and tack on 10 degrees and type it into the ATIS computer.

[OldTownPilot]

Originally Posted by dc3flyer

In most places I don't think it really matters THAT much. Winds are also given 10's of degrees (such as 180 or 190) instead of actual degress (such as 183 or 187). So are a few degrees going to matter? Not to mention the winds change a little more often than the reports.

In the lower 48, what is the maximum difference, 18 degrees?

Its magnetic.

Maine is just under 19 west, and NW Washington is just under 19 east. The difference between the METARs and the ATIS' here is 20 degrees.

In the corners of the country its something that you have to concern yourself with, especially in XC planning. The difference between a 30 and a 50 degree crosswind can be substantial too, especially for a low time private pilot.

[Fandango Flyer]

It's pretty far in the back of my head, but I sorta remember something about that if the winds are written they are true, and that if they are spoken they are magnetic.

[7700]

Here's a good way to remember True vs Mag Winds:

Anything you read (METAR's, TAF's, FD's, Wx Charts) is True

Anything your hear (ATIS, ASOS) is Magnetic

[400A]

Text is True, all else is magnetic

[Dazzler]

Originally Posted by 400A

Text is True, all else is magnetic

Not true - you read the numbers on the runway, which is text, but that's MAGNETIC not TRUE

[400A]

Originally Posted by Dazzler

Not true - you read the numbers on the runway, which is text, but that's MAGNETIC not TRUE

Paint doesn't count, see my invisible disclaimer in above post.

[Beehive]

Our metar gets a copy and paste to ATIS. It sounds like I read it.
Maybe that's why tower gives the wind on takeoff and landing clearance.
-13 degrees variation.

[Sunburn]

7110.65 says that the ATIS winds shall be in magnetic

[Inverted]

I asked the tower this at KLVK and they give winds in Magnetic. It only makes sense it takes the work out of converting.

[nocturnalaviator]

Originally Posted by Dazzler

Not true - you read the numbers on the runway, which is text, but that's MAGNETIC not TRUE

LOL you ask a question, you get an answer, and then tell the guy he's wrong on a technicality, lol good one! If you gave me that answer in person i'd tell you I rest my case, inform you that you know it all, and walk away. But hey give someone a jerk answer, get a jerk response.

[atcbrownie]

I have never read anything other than what comes out on the metar nor have I ever heard of anyone else doing so. The AFB I was at our atis was automated directly from the metar. Whatever the metar says is what the controller is going to tell you.

[sdfcvoh]

Originally Posted by 7700

Here's a good way to remember True vs Mag Winds:

Anything you read (METAR's, TAF's, FD's, Wx Charts) is True

Anything your hear (ATIS, ASOS) is Magnetic

To put this into further perspective, what are you doing when you READ numbers?... You are flight planning....

Flight planning begins with TRUE courses and headings, and that is the reason printed material is true and not magnetic. Just in case you were wondering...

[clestudentpilot]

It is not always true in print that the winds are true. Where I was at, it was a manual weather reporting station. The instruments they read the winds from were the same whether you were writing down the METAR information to record the ATIS, and to call FSS with, or giving it to pilots in a takeoff or landing clearance. While this contradicts things, I asked some people who are much more knowledgable than I am when it comes to being a whether observer, since I am not one, I received the answer that the NWS prefers true, the FAA prefers magnetic. The NWS has won out in these scenarios. To obtain a wind reading, you observe the wind for 2 minutes, and take the average of the 2 minute reading. I won't get into details on gusts factors, or variable wind directions. When an automated station give the winds, whether on a frequency on ASOS or AWOS, or in a METAR, the same is true, a 2 minute average. The automated stations are obviously much more accurate, and the machine can automatically change the direction for magnetic direction in an AWOS or ASOS recording you listen to. At controlled fields, they may have to look at the METAR readout from the AWOS, and convert before recording the ATIS. For all intents and purposes, a human weather observer just is not good enough to get the very precise winds when observing them. If the winds cary between 176 and 224 in the 2 minute interval, the observer may to average it say it varied between 170 and 230 to give a wind of 220, while someone else may see this as between 180, and 230 for 225, which would round to 230. What I'm saying is that humans just aren't good enough at the manual stations to get it as accurate as the automated stations can. That is why we didn't add or subtract anything when calling FSS with the METAR, it was so close that it was impracticle. Stations in Maine or Washington may do things differently though

[Guy]

Originally Posted by Fandango Flyer

It's pretty far in the back of my head, but I sorta remember something about that if the winds are written they are true, and that if they are spoken they are magnetic.

Give that man a cigar. He is right.

[Sunburn]

This is the reference I was looking for

7110.65 2-9-3
Include the following in ATIS broadcast as
appropriate:
a. Airport/facility name, phonetic letter code, time
of weather sequence (UTC). Weather information
consisting of wind direction and velocity, visibility,
obstructions to vision, present weather, sky condition,
temperature, dew point, altimeter, a density
altitude advisory when appropriate and other
pertinent remarks included in the official weather
observation. Wind direction, velocity, and altimeter
shall be reported from certified direct reading
instruments. Temperature and dew point should be
reported from certified direct reading sensors when
available. Always include weather observation
remarks of lightning, cumulonimbus, and towering
cumulus clouds.
NOTE ASOS/AWOS is to be considered the primary source of
wind direction, velocity, and altimeter data for weather
observation purposes at those locations that are so
equipped. The ASOS Operator Interface Device (OID)
displays the magnetic wind as “MAG WND” in the
auxiliary data location in the lower left-hand portion of the
screen. Other OID displayed winds are true and are not to
be used for operational purposes.

[Beehive]

The METAR, ATIS, AWOS and ASOS are magnetic.
Someone in KS is probably responsible for HI weather. They account for magnetic variation.
But with today's FAA it's hard to say (twilight music).