a loss of engines thrust, an uncommanded slats retraction, a shift of the aircraft's center of gravity, and an uncommanded deployment of the thrust reversers and spoilers, all of which were ruled out due to lack of evidence. There was no evidence that the stall warning had activated due to true stall condition, so a false alarm was the most likely scenario. A false alarm might have been caused by a faulty Flight Warning Computer (FWC), leading to the activation of the stall aural warning, with or without the stick shaker. A damaged angle of attack sensor and an erroneous calculation on the speed could also produce a false stall warning. These were the possible sources of the false alarm aboard Flight 431. However, investigators could not determine the source due to lack of data. Pilot's action The occurrence of a stall condition is extremely rare during an aircraft's take-off or climb phase. Recovery procedures for stall are mainly applied for an approach or enroute phase. Flight crew are not trained to handle a stall condition during take-off or climb phase. The described procedure in Airbus' Flight Crew Operation Manual (FCOM) stated that in case of the presence of a stall warning with the activation of the stick shaker, flight crew should immediately and simultaneously apply full maximum engine thrust and reduction on the aircraft's pitch attitude and it should remain in that position until the stick shaker stops. The stick shaker should have immediately stopped by the time the flight crew applied this procedure and the pitch attitude should be maintained for some period of time so that the aircraft could gain more speed while also minimizing the loss of altitude. On the accident flight, First Officer Mulli (the pilot flying) immediately applied the supposed recovery procedure as soon as the stall warning appeared. The aural stall warning combined with the activation of the stick shaker would make the First Officer to maintain his action. The change in the aircraft's pitch to nose down attitude would also cause the First Officer to feel like the aircraft was actually descending due to the change in vertical acceleration. By putting the aircraft into a nose down position, he expected to stop the stall warning, which didn't happen until the aircraft reached a very low altitude. A false alarm could be identified by the flight crew had the information on a red