Can anyone explain how a Boeing 777-200 can vanish without a trace?

How can it simply disappear without any indication of an in-flight emergency from the flight crew?

Does its disappearance and lack of any physical evidence suggest a catastrophic in-flight emergency which unfolded so rapidly that it caught the flight crew off guard and unable to send a distress signal?

Is it possible for someone other than the flight crew to disable its transponder or alter its radar signature to render it undetectable?

  • $\begingroup$ "is that mean that If got bad or emergency happen in the plane and if its very fast one there's no chance that the pilot can ask for help first?" I do not even know what that is supposed to mean? $\endgroup$ – abelenky Mar 11 '14 at 19:46
  • $\begingroup$ hypothetically if a bomb exploded under your seat you won't be able to signal ATC about it, otherwise it's a dupe $\endgroup$ – ratchet freak Mar 11 '14 at 20:00