First off ...ICAO says it's hectopascal...millibars have been out since General Motors was still Corporal Motors ....
I have had 2/3 cases where , when the QNH, is < 1000, and you pass it too American crews they set it as inches ...mostly because our colleages in the US pass (Scott will bear me out here ) it without the mentioning the two ...ie. 29.93 is passed as 993 and so on ....hence the reson that , ICAO (I think) recommends the QNH is passed as xxx hpa when it is less than 1000 hpa ...a case in point was a Delta flight into Dubai the other night whichset himself 500 ft above /below what he should have been ...mode C check brought the error to light ...fortunately ...
Question: Why is the UK MATS manual always quoted as the "bible" of all ATC issues ? It ONLY applies to the UK ....not all ICAO centres / countries .....surely it should be what does ICAO say ...THEN the local ANR's and then and ONLY then what does Manual ATS say ...in that order ...
No offense to the UK MATS ...wonderful document in it's own right ...
