Altimeter setting practices

Flightnerd

Flightnerd

Well-Known Member
So I've had a few of my students ask. When our altimeter is set to the latest setting, yet reads different from field elevation, should we reset it to field elevation, leave it at the current setting and note the difference, or just forget about it because it doesn't matter all that much? The AIM says there's a problem if you are 75 feet off, but I'm talking like 60 ft. I tell my students to keep the same altimeter setting and don't come up with our own, because everybody else has that setting and keep us from hitting other planes.

Get what I'm saying?
 
I fly with the broadcast local altimeter setting below 18k. Generally speaking, setting it to actual field elevation or using the ATIS/AWOS setting isn't going to yield enough of a difference to get you violated, but I like being on the same piece of music as everyone else in the airspace around me.
 
Remember, "Field Elevation" is defined as the highest elevation of any useable landing surface. This can vary significantly compared to what the ramp elevation may be, or wherever you are when you set the altimeter.
 
I know at one airport I flew out of on a regular basis, that if you set the AWOS altimeter setting, it would show you 40-50 ft off when you were sitting on the ramp. By the time you got to the end of the runway, you were within about 10ft of field elevation.

With that said, twice in the past month, at two different airports, the tower recorded the wrong altimeter setting on the ATIS. When I checked in with ground, I got the correct altimeter, all was right with the world, and I mentioned that they might want to check the ATIS. Remember that ATIS information can be an hour old, even when it's "right."
 
Flightnerd said:
So I've had a few of my students ask. When our altimeter is set to the latest setting, yet reads different from field elevation, should we reset it to field elevation, leave it at the current setting and note the difference, or just forget about it because it doesn't matter all that much? The AIM says there's a problem if you are 75 feet off, but I'm talking like 60 ft. I tell my students to keep the same altimeter setting and don't come up with our own, because everybody else has that setting and keep us from hitting other planes.

Get what I'm saying?
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I always set the altimeter setting provided to me by ATC or ATIS/AWOS/ASOS, for the rationale you provided.
 
Autothrust Blue said:
I always set the altimeter setting provided to me by ATC or ATIS/AWOS/ASOS, for the rationale you provided.
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Ditto, I belive even the aim says to only use field elevation if you can't get the current altimeter setting, and if you use the given setting and your altimeter is of by more than 75' you aren't legal anyway.
 
I always use the broadcast or ATC setting. That way you have something to suspect if the altimeter doesn't look right. Most glider pilots just set it to 0 MSL, since they are generally more concerned about AGL. I personally don't do this.
 
drunkenbeagle said:
I always use the broadcast or ATC setting. That way you have something to suspect if the altimeter doesn't look right. Most glider pilots just set it to 0 MSL, since they are generally more concerned about AGL. I personally don't do this.
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Need two altimeters.

It depends where I take off from. Sometimes we don't have any broadcast weather so we have to set it to field elevation. But interestingly we have 3 towered airports within 15 miles of each other and they have altimeter settings usually quarter an inch apart. So depending where you takeoff from you could initially be around 250 feet off.
 
I particularly enjoyed hearing a (presumably) new Washington Center controller issuing altimeter settings to aircraft in her sector. Both our departure and destination, which were only a hundred or so miles apart, were reporting 30.40ish, and she was issuing 29.92 to everyone that checked on. I made a comment that there must be a helluva pressure gradient in the area, but she didn't quite get it.
 
drunkenbeagle said:
I always use the broadcast or ATC setting. That way you have something to suspect if the altimeter doesn't look right. Most glider pilots just set it to 0 MSL, since they are generally more concerned about AGL. I personally don't do this.
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QFE scares me.
 
drunkenbeagle said:
I always use the broadcast or ATC setting. That way you have something to suspect if the altimeter doesn't look right. Most glider pilots just set it to 0 MSL, since they are generally more concerned about AGL. I personally don't do this.
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You're in Florida, what difference does it make?
 
Heck the russians are now in FLs too, no more Meters. QFE might be ending there before too long.
 
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