Someone said:
Why have all these Q-codes anyway?
Its obviously a throwback from days when a/g communications relied on the Morse code. See
http://www.kloth.net/radio/qcodes.php for a very complete list!
I suppose the advantage of continuing to use such codes is that even when used verbally they provide clear and concise meaning - especially helpful in non-English mother-tongue areas of operations. For instance, in France you will often be told the "Fox-Echo" by which they mean QFE. Think also of uses such as QDM / QDR etc. - once you've learned them, its clear and less of a mouthful via r/t.
I suppose though that the heart of the question posed is whether or not it really necessary or helpful for us to use a combination of airfield and sea-level datums at all: why not just one seal -level "pressure setting" as in the US (and Australia and probably other places for that matter)? I have heard it argued that for instrument flight you are better off using QNH alone anyway - just do the mental maths for circuit and decision heights etc., avoiding the need to do similar mental gymnastics on the go-around, arguably a time when your workload will be higher.
This argument seems to make sense to me, and I find that it really isn't a hassle relying on QNH alone when in the US for example. Yet I always settle right back into using QFE when flying around here...
Would be interested to know what others think?
Andy