Originally Posted by
chevvron
Exactly, it's only in the unlikely event that ATC don't want you to change to QNH until you have passed the TL that you need to know it, otherwise as Chesty says, if you're at a flight level and cleared to an altitude, you set QNH and descend.
Fair point I suppose. Although in this case, I have to question why ATC aren't just clearing you to a intermediate flight level at or above the transition level. In 9 years of civil radar, and another 6.5 in the mil prior to that, I have never felt the need to pass the transition level. Nor can I see any benefit in a pilot not switching to qnh prior to going through the transition level. Unless I wanted to issue an unplanned stop descent.