One popular misconception is that a lot of people think that they need to apply the temp correction directly to their ALTITUDE. It is the HEIGHT above the aerodrome where the QNH or QFE is measured that needs correcting.
On the ground at the ARP our altimeters should read APT elevation with aerodrome QNH set whatever the temperature. In ISA a CAT1 DA (with 200'DH) for an airport of 2000' TDZE would be 2200'. If it was -20C you would increase the DH to 230' so the DA becomes 2230'. The marker HEIGHT of say 1500' would be adjusted up to 1700' giving a marker crossing ALT of 3700' etc.
It looks like the temperature correction issue needs to be standardised worldwide. In the UK we also have to consider the extremes like -20C in Inverness (and -20C in London in 1981).
If mountains were compressable like air there would be no problem.
