P-factor is extremely significant for helicopters in forward flight, because the propeller disc is almost horizontal. The forward-going blade has a higher airspeed than the backward-going blade, so it produces more lift. However, helicopters can control each blade's angle of attack independently (decreasing the angle of attack on the advancing blade, while increasing the angle of attack on the retreating blade) in order to keep the lift of the rotor disc balanced. If the blades of the rotor were unable to independently change their angle of attack, a helicopter with counterclockwise-rotating rotor blades would roll to the