To me, erratic changes in altitude and heading plus climbing above max recommended flight level indicate someone trying to get used to the controls and flying the aircraft at night.
You're assuming there actually were erratic changes in altitude. We really don't know there were, do we? We're told there were, but in the same burst of info they also told us the plane dropped 40,000 feet in a minute, which, even if it were possible would almost certainly not be survivable. Then, after miraculously pulling out of a meteoric dive the plane then headed west, then northwest, then west, then turned (get this) either north or south!
Huh? It turned? We declare that we know it turned but we can't figure out if it went North or South, right or left? Was there a cloud in our way or were we in the middle of some unreported magnetic polar flip at the time!
There has been so much inaccurate information about this incident reported over the last week that there shouldn't be any question what story wins this years Bullitzer Prize.
Why "news organizations" are willing to peddle "a high ranking source", "a source not authorized to speak", "the (?) Malaysian military" The? Really? Who is The"? Get some people at the mike willing to put their John Hancock on the bank note. There are no credible sources. The media, which normally is a fantastic retail source for compost has assumed the role of wholesaler on this one.
Even supposed official statements are clouded by confusion, like Rolls Royce "Rolls-Royce concurs with the statement made on Thursday, 13 March by Malaysia's Transport Minister Hishammuddin Hussein regarding engine health monitoring data received from the aircraft." That statement by the way was a denial that they received any data from the engines after the transponder was lost. In fact, another statement suggested they didn't receive any further data after 14 minutes prior to the loss of the transponder. Yet the media has, all day continued on with the narrative that the plane communicated for 5 hours. I suppose "We haven't been able to find anyone who is willing to go on record with the truth about what they know" is a pretty tough sentence for them to choke out of their mouths.
They have no shame.