Add 4 feet per thousand feet to the DH/MDH (whichever you are using) for each degree below ISA. If you are using DA/MDA, only apply the correction to the height above the airfield datum.
So, if your MDH is 1000 and the MSL temp is 0, your revised MDH is 1060.
Usually it's not worth applying until you get about 30 degrees below ISA.
Don't forget that it also affect MSAs.
Last edited by oxford blue; 13th February 2003 at 13:18.