The transition level is the first available FL available for use above the transition altitude and is calculated as follows:
QNH = 1000, SID terminates at 6000ft
Altimeter setting 1013 equates to : (6000) + (13 x 30) = 6390ft
The 30 representing ft per mb and the 13 the difference in QNH and 1013
Therefore transition level is FL80 since setting 1013 on the altimeter equates to 6390ft on QNH, to ensure 1000ft separation, first available FL is FL80
QNH = 960 TL = (6000) + (30 x 53 ) = 7590ft therefore TL is FL90
Generally though, its calculated automatically and displayed on the ATIS information screen in the tower.
Hope thats of some help
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Turn left heading 230, close from the left, report established
[This message has been edited by form49 (edited 17 November 2000).]