Interesting flight path. It has descended from F350 early in the flight, and then maintained F310 for the vast majority of the remainder. It's generally not hard to get a climb in that part of the world, so that would imply that they didn't want it. It's not an emergency, as they had a number of alternatives, and have seemingly held until the end of the curfew (by my maths) at Adelaide.
Appreciate it's all speculation, but given what you're seeing there, can you think of any particular explanation for that? If there's a technical issue that wasn't serious enough to consider an earlier alternative, my uninformed brain wonders why you couldn't just carry on to MEL given it's not much further along?
I'm no expert on the topic, but if the cabin pressurisation system broke, then I'd imagine they'd be needing to descend to an altitude well below 31K feet and would be diverting somewhere long before ADL...?
It is now being ferried to MEL
Being unable to climb would result in a greater fuel burn, though it would be partially offset by a slower speed (automatically calculated by the FMC). At first glance I'd have expected enough fat in the fuel plan to cover this...perhaps not.
The aircraft would have two airconditioning packs, so the loss of one would not lead to loss of pressurisation. But, it may impose an upper altitude limit. That seems consistent with the altitude that they used.
