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Altimeter setting: ATIS or approach control?

Mmmmmm Burritos

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I've noticed most pilots stick with the altimeter setting broadcast on the ATIS when approaching to land. This of course can be up to an hour old. Sometimes approach will give you another altimeter setting which may only be .01" off or so. Some pilots will put this setting in, whereas others (the vast majority) will stick to the ATIS setting.

Normally who cares, right? Well the other day the altimeter was probably .15" off since the last ATIS. We had the ATIS setting in (which was 50 min old or so) and got the "minimums" callout after the GPWS called out 100ft. It was a visual approach so no big deal.

So does approach always have the most current altimeter setting and should you always use it? I am leaning toward yes, and if the minimums are low, ask for a current setting (if not received) when beginning the approach.
 
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SkyBoy1981

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TRACON facilities usually have an up to the minute barometer reading right beside their controller's scopes. This is going to be more current than the altimeter taken from an AWOS observation that was put on the ATIS. So, anything given by an approach controller for the primary airport is always going to be current.

Center controllers, however, only use AWOS observations (usually that are put on the ATIS) to give altimeter settings. Sometimes I've noticed if a brand new ATIS comes out, the ARTCC computer systems may take a while to reflect this and the Center controllers are still giving out the old altimeter.
 

Vector4fun

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I work in an Approach and couldn't add a thing to what Skyboy said. We do get some big pressure swings when a front or large TSTM passes, but .15 in an hour would be pretty far out there...
 

Mmmmmm Burritos

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Vector4fun said:
I work in an Approach and couldn't add a thing to what Skyboy said. We do get some big pressure swings when a front or large TSTM passes, but .15 in an hour would be pretty far out there...

Yeah, I'm thinkin Cappy wrote it down wrong when he got it...
 

Singlecoil

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Sometimes, they will read off "XYZ altimeter xx.xx" which is the closest airport to your current position, but you are actually landing at a different airport. Sometimes that can be a factor if there is a big split.
 

FracCapt

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Mmmmmm Burritos said:
Sometimes approach will give you another altimeter setting which may only be .01" off or so. Some pilots will put this setting in, whereas others (the vast majority) will stick to the ATIS setting.

I always use whatever they tell me is the most current....because even if it's only off by .01", that means that I could flare 10' high or 10' low....which is why my landings usually suck....old altimeter settings. :D ;)
 
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