That’s the problem with hypoxia, it leads to mental confusion!
The pilots were so "confused" they couldn't make a couple of selections on the MCP to descend when the
CABIN ALTITUDE warning occurred at 15,000 ft (in your scenario). But, at some later time, when the cabin altitude was even higher and the pilots presumably even more hypoxic, they were compos enough to complete a more complicated task to, first of all, find the appropriate waypoints, then enter them correctly into the FMC, along with the airport identifier for Banda Aceh. Bull****.
