ceilings are AGL or MSL?

pilotod

pilotod

Pre-takeoff checklist
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I know I read this somewhere but I was asked and couldn't remember for sure knowing I had read something about this. My current understanding...METAR is AGL and so is TAF. But I know I read something else as an exception but I can't find it....yet.

Maybe I just found it. It's always AGL for the METAR and TAF but the FA is usually MSL unless it's stated for base as AGL or CIG. What an annoyance for the FA to be different.
 
You have it right. TAF's and METAR's are always AGL. Area Forecasts (FA) are always MSL unless the height is specifically tagged AGL or CIG (for "ceiling").

It may seem annoying that FA's are MSL, but they cover large areas where the terrain may vary but the clould bases are usually at a constant height MSL. That is generally more useful for enroute flight planning.
 
thanks....the reasoning behind that makes sense.

Ron Levy said:
You have it right. TAF's and METAR's are always AGL. Area Forecasts (FA) are always MSL unless the height is specifically tagged AGL or CIG (for "ceiling").

It may seem annoying that FA's are MSL, but they cover large areas where the terrain may vary but the clould bases are usually at a constant height MSL. That is generally more useful for enroute flight planning.
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Ron Levy said:
You have it right. TAF's and METAR's are always AGL. Area Forecasts (FA) are always MSL unless the height is specifically tagged AGL or CIG (for "ceiling").

It may seem annoying that FA's are MSL, but they cover large areas where the terrain may vary but the clould bases are usually at a constant height MSL. That is generally more useful for enroute flight planning.
Click to expand...

pilotod said:
thanks....the reasoning behind that makes sense.
Click to expand...
Yeah, understanding the reasoning usually goes a long way to helping someone remember.
 
I wondered how a 500 foot overcast in Denver worked...

AGL makes way more sense.
 
bartmc said:
Why is Area Forecast called an FA?
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Same reason PIREPs are UA's, winds aloft are FD's, etc. -- it all goes back to the development of the old teletype codes, and everyone who worked on that project is long dead. Some of them made sense (like weather warnings being WW's), but many didn't.
 
I bet if you dig hard, you find that no two character combo can be corrupted by a single bit error into another in whatever encoding RTTY utilized. (Was FAA's RTTY system Baudot? I forget.)
 
...millions and millions and millions of Little Yellow Dots...
 
scottd said:
Actually Ron you might have missed the memo...the winds aloft are now called FBWinds as I discuss in this that I wrote for The Front back in 2005.

FBWinds.gif
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Somebody needs to tell LockMart that because it still says FD in a DUATS brief.
 
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