"Michael" wrote in message
om...
Let's not forget that the
worst case temperature error at 200 ft and -50C is only 60 ft, while
altimeters can be up to 75 ft off in some cases and still be legal for
IFR use. There used to be a DH penalty for an inop middle marker
(either at the transmitter or receiver end) but this penalty no longer
applies. All this ignores the possibility that the pilost has a RADAR
altimeter available.

In the US, it is up to the pilot to decide whether in his particular
situation, given the available equipment and his skills, he should
adjust the minima as appropriate based on the expected temperature
error.

Michael

I've never seen, nor heard of a temperatures of -68F (at low airport-type
altitudes) that was not associated with an inversion. I suppose that it
might happen in Anarctica in the winter but there aren't any airports there.
In Alaska, when its -40F on the surface it is usually at least 0F at 1000'
AGL.

Mike
MU-2