Jetset
What we have to consider about UK is the low transition level. Having been holding at LAM at FL70 it makes good sense to include the word "altitude" in the descent instruction along with the QNH as this will (should) minimise the chance of error. I can't recall what would be a typical number of step descents below the holding level but I seem to recall it's not that many - standing by to be corrected.
In other parts of the world, Hong Kong for example, the number of step clearances below the (high) transition level tends to be more than LHR from memory. If "altitude" were to be included in each of these step clearances it would equate to over 100 minutes worth of RT usage based on 40 movements an hour for 16 hours and 5 step climb/descent instructions/movement (assuming no repeat instructions) - this in an already busy RT environment.
I tend to use the 'if the controller says "altitude" in an instruction then I'll read back "altitude"' method - it seems to work fine.
STP
Last edited by Steve the Pirate; 28th May 2012 at 00:02.