Takeoff and landing system

In an automatic control system for stabilising the position of a VTOL aircraft 20 during vertical take-off or landing, the position of the aircraft 20 relative to the landing site is monitored by a ground based sensing system 10 and information is transmitted 16, 22 to the aircraft 10 to control landing or hover operations. If the landing site is on a ship, the landing site sensing system can include an inertial sensing means 14 to compensate for roll of the ship. The aircraft 20 can also include INS means 26 to compensate for wind gusts. Electromagnetic clamping means 34 are provided to prevent take-off until conditions are desirable eg 0 DEG angle of roll.