Altimeter help "Standard" setting


I’m a little unsure on something on the altimeter in the a320, when ATC gives me the info I adjust it, but I’m just confused about the setting called “standard”

When should that be used if at all?


Above the transition altitude you should use the standard setting. In the US the transition altitude is 18000 feet, in Europe it varies and need to be looked up on charts. Below the transition altitude heights are given in feet, above we refer to flight levels.


Thank you, so for example then flying in US above 18000 ft I switch to Standard, will ATC also stop with any changes to the altimeter above this altitude?

yes above FL18 it’s standard / 2992 , under FL18 u will get local pressure from the ATC then use that one…

in RL many country’s use their own level , msfs uses FL18 as default

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Yeah just read that elsewhere on here about FL18 being the default global setting.

First I think you mean FL180, second it is a “transition altitude” so 18000 ft, everything above is referred to as flight levels.

29.92 inHg or 1013 hPa :slight_smile:

1013.25 hPa :upside_down_face:

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How many times did you succeed dialing that .25 in? :grinning_face_with_smiling_eyes:

The only thing inHg is useful for :joy::+1:.


Standard altimeter is a theoretic air pressure at sea level. But pressure does change with elevation and weather. Altimeter in a plane is used to gauge its altitude above Mean sea level, by setting the value of altimeter pressure to standard you ensure that every plane is playing off of the same playbook. If ATC tells you to climb to 20,000 feet and for me to climb to 22,000 nobody cares that in actuality because of weather conditions we are 18 and 20K above mean sea level there will be exactly 2K feet of separation between us as we pass each other. As we get closer to the ground actual atmospheric pressure and altitude above Mean sea level based on local pressure becomes important again because of the land features, mountains actual field elevation where you coming to land etc. So in US 18K feet is chosen as an altitude of where you tranistion from actual pressure to this theoretical standard and in Europe it’s done country by country region by region in a lot of cases airport by airport. Just historical reason I believe I don’t think there is a good scientific reason that it has not been standardized. So for practical purposes if I am at 20K at standard pressure altimeter above US highest airport which sits 10K above sea level the error between local pressure and the standard one needs to be 10 inches of mercury, for me to slam into the ground 1 inch drop for every thousand feet. I think it would be an extinction level even if it to occur But if Im on approach in poor visibility with standard altimeter of 29.92 when local altimeter is 29.72 and approach calls for 1500 hundred feet AMSL I am actualy at 1300 hundred feet 200 feet closer to the ground than I think I am and that becomes a big deal. Of course modern airliners also have a radio altimeter which gives you your altitude above actual ground level but your ILS approaches still rely on barometric altimeter setting to get you to the platform altitude and glide slope after that.

In the A320 you can enter the transition altitude in the MCDU on the PERF page. When you reach the transition altitude, the dials start to blink. You might already know this but I find it quite useful as it reminds you when to switch to standard.