Flight 370, yes, I’m still on it

If the plane lost cabin pressure, and someone was at the controls–pilot or passenger–would not a rapid descent to lower altitudes be one of the first things they did?  One which was not “radar evading”, but oxygen preserving?  And again, if the electronics were scrambled and they either didn’t know where they were, or how to read the instruments (if the pilots lost consciousness and one or more passengers were trying to fly the thing) you would see both a rapid descent and an erratic trajectory that leads, ultimately, to a crash, either from losing fuel, or from misjudging altitude, all while trying to reach someplace safe.

And what if most but not all passengers were killed in the initial decompression?  Perhaps some remained conscious, but not those whose cell phones were called.  Or what if the survivors panicked and tried to broadcast relentlessly on a broken plane radio and forgot about their cell phones?  I read once about someone who died in a parachute jump because they gave him a left handed parachute, and all he thought to do was paw relentlessly where the pull cord would have been on a right handed parachute.  They could see the marks. 

If the plane was hijacked, it serves no purpose to fail to announce by whom and why.  No terror is achieved.  Even if it was a coordinated attack, and failed due to terrorist pilot error, there would be people who could anonymously announce their “success”.  This is their way of operating.  Nothing is achieved by mystery.