May I draw your attention to a common misconception in 'Altitude Deviation' in the recent edition of CHIRP? The reporter talks about setting altimeters to 1013 as they pass the transition altitude, which is commonly believed to be correct but is not and for a very good reason. A pilot is permitted to set 1013 as soon as they've been assigned a flight level and I would encourage this, although to do so on the ground prior to take-off is perhaps unwise if this gives a negative figure on the altimeter, for obvious reasons. The transition altitude is defined as the altitude below which altitude should be referred to with reference to the QNH and above which with reference to 1013. It is NOT the altitude at which you change from one to the other. I've been an IRE for many years and one of the very common fail points I've doled out is when the QNH is low and a pilot changes from QNH to 1013 at the transition altitude but has been cleared to a low flight level, not for the action itself, which I usually retain as a strongly-worded debrief item rather than a failure point in itself, but for the effect it can produce. At [ ], for example, it's common to be assigned FL40, so in winter when the QNH is 980 or below (as happens quite regularly) there is 1000 ft. between the QNH and 1013, so a pilot who leaves it until the transition altitude (3000 ft. at [ ] before setting 1013 will overshoot their assigned level because FL40 is the same as 3000 ft. with a QNH of 980 hPa.
https://www.chirp.co.uk/
A simple point to understand but a mistake that many people seem to make for wont of not really thinking about what they are doing!
MA
