On 11 March 2018 an Unreliable Speed Alert occurred on a Bombardier Challenger, the Captain’s airspeed increasing whilst the First Officer’s decreased. The First Officer attempted to commence the corresponding drill but the Captain’s interruptions prevented this and a (false) overspeed warning followed. The Captain’s response to both alerts was to reduce thrust which led to a Stall Warning followed, after no response, by stick pusher activation which was repeatedly opposed by the Captain despite calls to stop from the First Officer. The stalled condition continued for almost five minutes until a 30,000 feet descent was terminated by terrain impact.