[stlnative]

Can anyone explain this? (Was a experienced pilot flying at this point or not?)

The New York Times, quoting American officials and others familiar with the investigation, said radar signals recorded by the Malaysian military appear to show the airliner climbing to 45,000 feet (about 13,700 meters), higher than a Boeing 777's approved limit, soon after it disappeared from civilian radar, and making a sharp turn to the west. The radar track then shows the plane descending unevenly to an altitude of 23,000 feet (7,000 meters), below normal cruising levels, before rising again and flying northwest over the Strait of Malacca toward the Indian Ocean, the Times reported.

[Jet Jaguar]

If the pilot was pulling circuit beakers to shut off comm and nav systems to disable them, I could see him shutting off the radar altimeter. Then as he is flying, he has to rely on air data instruments. If they were not calibrated correctly, or he did not have accurate barometric pressure settings, the altimeter could be off by several hundred feet at that altitude.

[Jet Jaguar]

If the pilot was pulling circuit beakers (or hijacker)

Added.