Transponder Landing System (TLS)

The TLS is, first and foremost, a precision tracking system. The system interrogates the aircraft’s Air Traffic Control Radar Beacon transponder and determines the location of the aircraft from the transponder reply to two ground-based sensors. The transponder’s location is computed in azimuth, elevation and range.

The system then provides guidance to the tracked aircraft. TLS guidance is transmitted to the aircraft by emulating ILS signals. When receiving TLS guidance, the pilot flies the aircraft like an ILS approach. No new aircraft equipment or avionics are required to benefit from the TLS. The aircraft must be equipped with a standard ILS receiver and an ILS display.

The TLS is tolerant to terrain that would otherwise preclude an ILS installation.

The first generation of the TLS utilized time-of-arrival measurements from a number of ground-based sensors to determine aircraft position. In the mid-nineties, ANPC modified this design to include angle-of-arrival measurements, allowing the sensors to be positioned closer together and increasing the accuracy of the positioning information. This improvement broadened the market for the TLS to include airports with limited available real estate for placing ground equipment. The TLS has since been approved by the FAA for use in the National Airspace System to supply APV approaches with electronic lateral and vertical guidance.  Because the system actively tracks the location of aircraft and processes the corrective guidance via software, the TLS is inherently capable of supporting offset and non-linear approaches, pending regulatory approval of such procedures.

Military Development

In cooperation with several armed forces units, including the United States Marine Corps and the Royal Australian Air Force, ANPC has packaged TLS technology into several mobile configurations to support forward expeditionary and disaster relief operations. Most recently, terminal area surveillance and support for reciprocal runway guidance have been added to the mobile system’s functionality, and a joint initiative has been established between the U.S. Marine Corps and the U.S. Air Force to develop the mobile TLS, dubbed “Rhino” into the joint service solution for military guidance and surveillance.

The Future of Air Traffic Management

The global aviation environment is faced with imminent change in the way air traffic is managed. The growing demands on airspace capacity will necessitate not only additional runway ends, but decreasing separation minimums, particularly in the terminal environment. To accomplish this, air traffic management systems will have to work synergistically from a common data set for reduced controller workload and positioning integrity. ANPC sees its technology, which uniquely combines the critical functions of terminal surveillance and approach guidance, as an important first step towards achieving integration and synchronization within air traffic management. The precision with which we track aircraft location can ensure redundancy and integrity of situational awareness by both controllers and pilots when used in conjunction with other positioning technologies such as GPS and ATCRBS, and increasingly intelligent airborne systems such as ADS-B and RNP-capable flight management systems.

ANPC will pursue new research and product development efforts with this end in mind as part of its commitment to “Bring People Together, Safely.”