Thanks Glueball, that's how I understand it as well.
QNE may also be of use during very
high atmospheric pressure, although one procedure that I saw told pilots to set the upper limit of QNH on the altimeter and just accept that you would be higher than indicated (= a 'safe' error). I guess it's only safe under IFR if all the aircraft have the same altimeter setting.
I think most modern altimeters are adjustable from 950-1050 hPa/mb, which should cover 99.9% of occasions; however, from wikipedia:
The highest barometric pressure ever recorded on Earth was 32.31 inches (1094hPa), measured in Agata, U.S.S.R., on December 31, 1968. Agata is located in northern Siberia. The weather was clear and very cold at the time, with temperatures between -40° and -58°.
The lowest pressure ever measured was 25.69 inches (870hPa), set on Oct. 12, 1979, during Typhoon Tip in the western Pacific Ocean. The measurement was based on an instrumental observation made from a reconnaissance aircraft.
Anyway, I agree that QNE is in common usage to mean 1013.2/29.92, but common usage doesn't make it right! Just look at all the supermarket check-outs with '10 items or less' displayed! How many times have you heard pilots refer to tracking a 'radial' from an NDB?
I am realistic enough to admit that the risk of misunderstanding is small in the case of QNE and that it doesn't really matter. Language evolves and all that, but it still grates a bit!
Actually, imprecise language can have safety repercussions. The Dan-Air 727 at TFN hit the terrain in the holding pattern because the controller said, 'Turn left' instead of, 'Left turn'.
What he meant was, 'Enter the hold, and once established, fly a pattern with left turns'.
What the Dan-Air crew understood was, 'When you reach the beacon, enter the hold by turning to the left'. A tragic misunderstanding.
I once had a co-pilot who read out part of a SID as follows: 'Turn at the
latter of 1500ft or 2 DME'. He didn't see the joke when I replied, 'So turn at 2 DME then? Why bother mentioning 1500ft at all?' What he thought he'd said was, 'Turn at the
later of 1500ft or 2 DME.'
There have been several cases of patients being injured or worse, when doctors whose first language is not English became confused over the meanings of 'prescribed' and 'proscribed'.
OK, rant over. I'll crawl back under my rock!
