Originally Posted by
stevelup
The instructors that fall into the first category above?
Don't fly with them any more - they are clueless... God knows what other bad habits or misinformation they will be imparting upon you.
Do you know the context in which this is alleged to happen? If not, you are making quite a jump to conclusions.
There are circumstances where mode A is mandated, even if mode C equipped. Usually it will be in the AIP, or by ATC request, or because you have a duff encoder which is not all that unusual.