scope:

This specification defines an Interphone Switching System to be used in an air traffic control facility. This specification describes a Western Electric Type 301A Interphone Switching System (WECO Designation J-53048). The system may be used in TRACONs, ATC towers, common IFR rooms, RAPCONs (Radar Approach Control), and small air traffic control centers. The system is a "Direct Access Type System," requiring a pick up key for each circuit appearing at each position. Although the system is designed to provide voice communication for a maximum of 42 control positions, facilities having more than 30 positions may find this system restrictive in operational flexibility as well as being economically expensive. Under certain conditions this system may be expanded beyond the normal 42 maximum position capability. This specification, as compiled, should be used for leased services only. The equipment, features, options, apparatus, and hardware, position-to-position and facility-to-facility relationship, circuit terminations, and types of signalling, etc. are stated herein.