Hello Guys,I was flying a circle to land today and I choose to do it with V-NAV PATH, Speed Interv. L-NAV. Approching the FAF ( 3000 feet ) I've selected my alt on to the MCP ( 900 feet ). On the FAF the plane started the discend as planned, approching the altitude the FMA went for V-NAV ALT instead of ALT- ACQ and ALT HOLD ( as it should ). My question is: Is this normal with NGX?Thanks all.

Yes, that is normal in the NGX.VNAV ALT is a Boeing option that stops VNAV from disengaging at an altitude not in the FMC.( the NGX uses this option )To leave VNAV ALT you must set a different altitude and press ALT INTERVENTION.( you could think of VNAV ALT as a sorta " ALT HOLD " for VNAV. )Fred.

What Fred said. Here is another advanced item. If you go to VNAV ALT on an approach segment (leg), repeat must be approach, the plane will get "unstuck" from VNAV ALT and resume descend as soon as the MCP altitude is set to at least 300 ft above current altitude (current altitude is determined by the altimeter from the master AFS side).This is handy if say ATC asks you to descend to the restriction altitude at the initial approach fix and then you receive a "cleared for XXX type approach runway YYY". The plane will resume descend (744 users : same there too).

Thank you so much guys. Really good tec. knowledge here. So basically different operators can choose different mode?