In response to Mark , if all timings are correct then the A330 lost contact about 3 hours before landing at Paris. The natural route is over water nearly all the way. I would suggest a point some approx 1400 miles from Paris out into the Atlantic to the South-West would be the vaugeist of approximations.
That's going to make a SAR operation difficult. Wonder where aircraft/boats etc are going to be provided from? Strange choice of terminology with "dropped off radar" - maybe implies a sudden chance of circumstance rather than a problem where there was constant radar changes and discussions with the flight deck.