flight instructor who raised the alarm about the so-called “20th hijacker” has been given a $5 million (£2.5 million) reward by the US government even though his tip failed to prevent the September 11 terror attacks. Clarence “Clancy” Prevost, a former US Navy pilot who taught at the Pan Am International Flight Academy outside Minneapolis, became suspicious of Zacarias Moussaoui when he wanted to learn to fly a jumbo jet without showing any interest in take-off or landing. The French national - the only person ever convicted in the United States for the September 11 attacks - was arrested on...