Dynamite,sorry about the late response-I had to dig it up in the Canada AIP.the AIP refers to 'high alt settings(so we must have them occasionally)..It refers to pressures above 1050mb-31.00inches....Most Altimeters can't adjust 'higher' than 31#,so the 'procedure' is to revert to a datum of 31inches ,below the Trans level,thence ,if adjustable reset to the 'actual'
on the approach.If unable to reset datum higher that 31inches,'bug up'the minima 1/4 miles+100' the the charted limits for each0.1 reading above 31*(this of course doesn't apply to Cat2/3 ops(rad alt))
It doesn't happen very often,once in 37 years of airline flying!!!
cheers
