How did 911 hijackers take control of the airplanes?

The 9/11 hijackers took control of the airplanes by using a combination of surprise and intimidation. They boarded the planes with box cutters and other small weapons, which were not considered significant threats at the time due to security protocols. Once in the air, they overpowered the flight crews and passengers, quickly taking control of the cockpits. This coordinated effort allowed them to redirect the aircraft toward their intended targets.