What is using OM subst. check via DME
There are often approaches around where the OM check requires the use a DME distance and altitude instead of the beacon.
Following the logic of LEM, is there a rule for @ OM altitude, e.g. if DME dist > then given OM dist then .....,
if DME dist < then given OM dist then ....? I can't figure one out.
While my logic may be fallible, I seem to find that if a DME dist > given value at the spec OM alt., it can be either
1) flying down the lower lobe of the GS (definitely not safe) or
2) flying with OAT > ISA (which is OK)
Can somebody check my logic here.
thanks