Altimeter settings

[Luis Hernandez 570]

PFE offers an option to adjust it so that ATC gives the altimeter setting in inches of mercury, or milibars (hPa). But in the real world, where is inHg used? I know Colombia, Canada, Mexico and the US use inHg, but which other countries? Where do they use mbar? Are there other units used (maybe China and the former USSR)?Best regards from Colombia,Luis Miguel

[DC_Ed 3]

PFE offers an option to adjust it so that ATC gives the altimeter setting in inches of mercury, or milibars (hPa). But in the real world, where is inHg used? I know Colombia, Canada, Mexico and the US use inHg, but which other countries? Where do they use mbar? Are there other units used (maybe China and the former USSR)?Best regards from Colombia,Luis Miguel

I know milibars are used in pretty much all of South America (except Colombia as you say), in Europe and former Soviet countries.

[Great Ozzie 101]

This is a very interesting question (to me)…For us flight sim guys & gals… just remembering to hit the “B” key is sufficient, no matter where you are in the World. Not so for RW Pilots, as you (indirectly) point out Luis. :-)I hazarded a guess with Australia, but when I went to look at Sydney's current Metar (on Weather Underground) I saw a “Q” in front of the Altimeter setting (indicating millibars of course).In a brief search, I could only find the 3 North American countries & Colombia (as you said) that have the "A" for the Altimeter Setting. "Altimeter always prefixed with an A indicating inches of mercury." From Metar Abbreviations (a .pdf from NOAA.gov). I am very curious to know why Colombia decided to use English Units (in this case). :( Here's a brief but interesting read from NASA's ASRS (Aviation Safety Reporting System) on International Altimetry emphasizing how critical it is which Standard (inHg or mbar) that one should be using.This reminded me of the Mars Climate Orbiter that crashed :( due to a mix up in English (which it was using) vs. SI/Metric Units (which it should have been using). Not precisely the same :( but a programming error none the less, using the wrong Units.