It's as old as game-playing itself: to improve your chances of winning a game, you need to discover your opponent's private information and use it against him.
Along the way, speaking to the hijacker, the pilot realized the man did not speak French. So he used the plane's public address system to warn the passengers in French of the ploy he was going to try: brake hard upon landing, then speed up abruptly. The idea was to catch the hijacker off balance, and have crew members and men sitting in the front rows of the plane jump him, the Spanish official said.
...It worked. The man was standing in the middle aisle when the pilot carried out his maneuver, and he fell to the floor, dropping one of his two 7 mm pistols. Flight attendants then threw boiling water from a coffee machine in his face and at his chest, and some 10 people jumped on the man and beat him, the Spanish official said.
Why didn't the hijacker sit down during landing? Not knowing French and hijacking a plane bound to France, a plane in which passengers and members of the crew are likely to know a little French, may not have been optimal. But standing up during landing?
Addendum: Andrew Roth at Club for Growth remarks that the pilot, crew, and passengers "opened up a can of game theory" on the hijacker. Well put!