I try to set the transition alt to 6000f in the CDU, which is the transition alt in the UK. Not like the US were it is 18000f. But on desent, I get a amber warning that the altimeter is not set to local, when below 18000f? This is too soon, why is it not 6000f as desired? In the old PMDG I remember being able to pre-set the QNH, from STD to local, before transition. Is there something I am missing in the FMC, or does the captain and F/O HPA have to be synchronized? jools

Where did you set it? I hope not on PERF INIT, did ya? Arrival TL need be set on DES FORECAST page. Can be accessed from DES VNAV page, then it's around LSK6L or thereabouts. Then you can enter TL, ISA deviation and QNH. If you do all that don't forget to execute your changes.

Go to the descent page-> then click forecast-> dial in the TL for your arrival airspace... Rarely is the dep and arr TA/TL the same value.Have a safe flight!

OK thanks. Wow thats a quick reply thanks. Jools

Is there something I am missing in the FMC, or does the captain and F/O HPA have to be synchronized?

Yes - the air data computers run off the baro settings on each side. If there is a disagreement between the altitudes reported by each air data computer, you will get an "ALT DISAGREE" warning on the altitude tape.

Yes - the air data computers run off the baro settings on each side. If there is a disagreement between the altitudes reported by each air data computer, you will get an "ALT DISAGREE" warning on the altitude tape.

Only if greater than 200ft for more than 5 seconds.