Not surprised, Golden Period
"It's possible that the military radars were switched off as we operate on an 'as required' basis."
"In some cases, they are simply switched off except during training and when a threat is expected."
http://www.reuters.com/article/2014/03/15/us-malaysia-airlines-defence-idUSBREA2E0JT20140315
The reality, analysts and officials say, is that much of the airspace over water - and in many cases over land - lacks sophisticated or properly monitored radar coverage.
Analysts say the gaps in Southeast Asia's air defenses are likely to be mirrored in other parts of the developing world, and may be much greater in areas with considerably lower geopolitical tensions.
"Several nations will be embarrassed by how easy it is to trespass their airspace," said Air Vice Marshal Michael Harwood, a retired British Royal Air Force pilot and ex-defense attache to Washington DC. "Too many movies and Predator (unmanned military drone) feeds from Afghanistan have suckered people into thinking we know everything and see everything. You get what you pay for. And the world, by and large, does not pay."