Authorities reportedly looking at flight engineer, plane altitude in missing Malaysia jetliner investigation | Fox News
"Authorities are also examining the possibility that the plane flew at an altitude of less than 5,000 feet to avoid radar coverage after it turned back from its planned route to Beijing, the Malaysian newspaper New Straits Times reports.
The newspaper said officials are reviewing the plane’s flight profile to determine whether it used “terrain masking” techniques during the time it disappeared from radar coverage.
"It's possible that the aircraft had hugged the terrain in some areas that are mountainous to avoid radar detection,” an official told the newspaper. “The person who had control over the aircraft has a solid knowledge of avionics and navigation…
it passed low over Kelantan, that was true.”
Kelantan is a province in central Malaysia."
If this news is correct, it contradicts the hypoxic pilot theory, unless that happened after another climb out. Passengers must have been out or controlled because they would likely notice being at less than 5000'