Fuel usage depends on range and payload and flying conditions. Unexpected head winds, flying below FL30, trying to ascend to FL45, etc. all would burn up a lot of extra fuel.
Typically these aircraft are only given enough fuel for 45 minutes extra flying time. India is a long way off, at the end of their range under normal conditions.
My guess the pilot calculated his range, saw that he couldn’t make, especially flying under FL10 to avoid Indian radar, and dove in hard to keep floating debris to a minimum.
I like your theory. Hopefully we’ll find out.
Then I'm lucky to be alive, as it has happened to me on multiple occasions where my flight was delayed for more than 45 minutes while in a holding pattern waiting for permission to land.
India is a long way off, at the end of their range under normal conditions.
Not correct. From the position of their last reported voice contact near Vietnam it is only about 2/3 as far to, say, Hyderabad, India, as it would have been to continue on to Beijing, not taking into account wind currents.