Thrust varies with throttle setting, airspeed, altitude and air temperature. This allows a glider pilot to lose altitude without gaining excessive airspeed. This causes an increase in altitude which minimizes altitude loss and airspeed gain. The speeds needed for takeoff are relative to the motion of the air (indicated airspeed). Lag error is only significant around the time when the airspeed or altitude are changing. True airspeed (TAS) is CAS corrected for altitude and nonstandard temperature. The data from the sensors are used to calculate numerous factors including airspeed and altitude. At low speeds and altitudes, IAS and CAS are close to equivalent airspeed (EAS). Aircraft speed records are based on airspeed, rather than ground speed. The autogyro has an unpowered lifting rotor, relying on its forward airspeed to generate lift. The F-104 set numerous world records, including for both airspeed and altitude. The dynamic pressure measured can be used to determine the indicated airspeed of the aircraft. Its estimated airspeed at was Mach 4.2. Mach number is a function of temperature and true airspeed. The airspeed and attitude of the plane are adjusted for landing.