Originally Posted by 2 sheds
I get the impression that you are saying that you will accept a level report based on any old setting and make a mental calculation to decide if it is within tolerance. Very professional - what conversion are you using, do you correct it for temperature and pressure,
I find 30' per millibar, the way I was taught, works just dandy. You cannot force a pilot to fly on your QNH in class G just because it makes it easier for you.
who has authorised that procedure,
Are you serious? Mental arithmetic should be an authorised procedure now?
and what chance is there of you making an error if the Mode C is out of tolerance and you are busy?
Practice seems to alleviate the risk.