Aerodrome Forecast/observation Wind Direstion

[Metro Boy]

TAF's and METAR wind direction is in degree's true yet the ATIS or AWIB reports it in magnetic. Wouldn't it be more logical for the forescasts to be in magnetic as well?

[Arm out the window]

Unless it's changed recently, I think TAFs and TTFs are in degrees mag, don't know about AWIB - would make sense for it to be in line with that as well.
Pretty sure ARFOR winds are in degrees true.

[turbantime]

Arm out,

Metro boy is right. As a general rule of thumb, what you get on paper is in degrees true except the ATIS. Ie ARFOR/TAF/TTF/METAR/SPECI/RSWT/Grid point forecasts. What is heard is in degrees magnetic, ie ATIS/AWIS/AWIB.

At the very least you would think the METAR would be in degrees magnetic as in most cases it is derived from the same automatic station that delivers the AWIS/AWIB which is magnetic.

[GearOff]

The only logic I can come up with for having the TAF in degrees true is so that pilots don't have to remember which forecasts indicate true, and which ones indicate magnetic. Clearly, an ARFOR or GPF couldn't indicate magnetic due to the large forecast area often covering multiple isogonals of variation. So rather than having one rule for ARFORs etc and another for TAFs, people can just remember the distinction turban mentioned - if it's on paper it's true if it's spoken (i.e. ATIS or by ATS) it's magnetic.

I do tend to think the METAR would make more sense in magnetic though! Maybe the line gets too blurred with TTFs....Who knows. If it ain't broke....She'll be right mate

[RENURPP]

If the forecaste wind was guarenteed to be within 10 degrees it might make a difference, otherwise............................

[Capt. On Heat]

I always thought the reason was because of WHO gave out the wind. Metservice use true and ATC (ATIS/SPAR etc) don't.

[Agony]

The way I was taught to remember it is.............

"The man in the tower is the only one untrue"

Of course that now includes the AWIB etc as well.

No disrespect to any ATC guys/gals

[gas-chamber]

And, unless you are sitting some theory exam where they try to trip you up with cross wind or tailwind component, in a country where the variation is only in the order of 5 to 10 degrees, it is hardly worth considereing. I never yet found a wind direction absolutely constant, except totally calm. Just take off and land into what looks like the best headwind component if you possibly can and if you can't, make sure the runway is long, wide and hopefully straight, with any slope in your favor.
Runway direction numbers are rounded off to the nearest 10 degrees magnetic and they go outside that limit as the variation changes over the years. But the painters don't rush out and paint new numbers on the threshholds as soon as the difference hits 11 degrees, so it's all a bit academic to be splitting wind direction down to the nearest few degrees. Exam theory, but you need to know it to pass the IREX etc. You may even get the occasional line check capt who can remember it and so asks it, if it amuses him to delve at that level.
Now, if you ever get up to Canada, where the variation can be huge and change over a short distance, everything is in degrees tru, including the runway direction itself.

[missy]

Wind readouts by a/c, are they magnetic or true?

[iceblock]

Wind direction read of the FMS's CDU screen is True. Generated wind vector on CRT screen is Magnetic. I assume this is standard for all aircraft types??