The plane was over the sea when it went silent. By the time you scrambled the jets, and got them headed that way, figure an hour. An hour at flight speeds would be another five hundred miles or so. Air to Air radar of the kind normally installed on interceptors reach far less than half that range. Then there are other nations airspace to consider. If a Malaysian fighter approaches the nation of Viet-Nam without permission there is a phrase for it. It is called an act of war, or at a minimum, a hostile act.
If fighters from one nation enter another without permission, which is not often granted, the one being violated starts screaming invasion before anything else is done.
Radios tend to be fairly unreliable at a distance. By some walkie talkies from the store, and go to a large concrete building. Then have one person inside and another outside. Reception will be poor, and at any range, non existent.
In two hours, that passenger jet had covered at least seven hundred miles. That is a long way for radios to reach, and if I was the controller, I might well just assume that the plane had exceeded the range. Sunspots, atmospherics, and a host of other reasons affect radios in a lot of ways.
Look at the Air France flight that crashed. Everyone kept assuming that there was radio problems until the time to land came and went and then the time remaining in fuel was exhausted. It is human nature to assume that it is a small problem, because history teaches us that it usually is a small problem. There are very few catastrophic accidents, but a lot of little things that go wrong that do not lead to disaster.
Even if you do scramble fighters, they can do little but fly next to the plane and call on the radio. Helios Airlines flight demonstrated that. The pilots of the fighters thought they saw someone waving in the cockpit.
We scrambled fighters for Payne Stewart's plane. http://en.wikipedia.org/wiki/Payne_Stewart#Death All they could do was escort the plane until it ran out of fuel and crashed.
Remember the situation with Bolivia One? http://www.theguardian.com/world/2013/jul/03/edward-snowden-bolivia-plane-vienna
That was a regular plane, not a fighter and the airspace issue was a huge diplomatic incident. Imagine if Bolivia One had just kept on flying where it wasn't allowed to go. Now imagine if Bolivia One was a fighter. Wars are started by such misunderstandings.
Now, here is the dirty little secret. Somewhere in an office in the US Government, they know exactly where the plane went down.
When Korea Airline flight 007 was shot down the Government was using sensitive receivers to track even the weakest radar signals. These secret facilities were the great grandsons of the same equipment that we used to track K-129 in 1968 and how we knew where it was when it sunk. Please don't tell me you think that we have lost that ability in the modern era with Satellites that offer real time information on anything anyone wants to see. No, someone in the Government knows, and is unwilling to say lest they reveal sources and methods, two things that are more valuable than the location of a downed airliner. If you doubt me, then remember that General Dempsey just said that it will cost hundreds of billions of dollars to fix the damage that Snowden has done, because he's been revealing the sources and methods used by the unintelligence Organizations.
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