A Radio Beacon and Receiving System for Blind Landing of Aircraft

A radio beacon and receiving system is described for use at airports to permit the blind landing of aircraft under conditions of no visibility. The system comprises three elements to indicate to the pilot the position of the aircraft as it approaches and reaches the instant of landing. Lateral position (that is, landing field runway direction) is given by a small directive beacon of the same type as employed for guidance on the airways, differing only in the use of smaller loop antennas and lower power. Longitudinal position along the runway (that is, approach) is given by a marker beacon. Height is given by an inclined ultra-high-frequency radio beam, used in such a way as to provide a very convenient gliding path for the landing airplane, free of all danger from obstructions. The same medium-frequency receiving set required for obtaining radiotelephone and radio range beacon service on the airways is utilized for receiving the runway localizing and marker beacon signals. The course indications of the runway localizing beacon are observed on the same vibrating reed indicator as employed on the main radio range beacon, automatic control of receiving set sensitivity being provided to maintain substantially constant reed deflections regardless of the distance between airplane and transmitting station. The marker beacon indications are received aurally. A special high-frequency receiving set is required to receive the landing beam signals. The rectified output current of this set is passed through a d-c microammeter mounted on the instrument board.