Indian radar
It's remarkable that India's radar covering the Andaman Islands was turned off at the time MH370 might have flown over because apparently "it was too expensive" too keep it on all the time, although I'm sure they really didn't want to have to reveal that information.
It makes you wonder how many other countries' radar systems are not all they're cracked up to be, which would of course improve the chances of MH370 having successfully flown over other areas.