From what I can recall, AF447 was stalling but the fly-by-wire system was stabilising the stall. Normally the FBW system wouldn't let the pilot stall but an earlier event caused it to enter some kind of unusual mode. That same event also made the pilot mistrust the instrumentation for the remainder of the flight. Because of this and the stable handling (+ bad visibility, lack of training and a whole load of other contributing factors) he didn't believe his speed was low enough to be stalling.