The Federal Aviation Administration (FAA) and partners Northrop Grumman and ACSS (a joint venture between L3 and Thales) have completed a series of successful flight tests of the sense-and-avoid avionics system for Unmanned Aerial Systems (UASs).

The FAA TCAS Program Office is developing the advanced Airborne Collision Avoidance System (ACAS) as a successor to the Traffic Alert and Collision Avoidance Warning System (TCAS) to support the objectives of its Next-Generation Air Transportation System Programme (NextGen).

All ACAS X variants detect conflicts with intruder aircraft, issue Resolution Advisories and coordinate maneuvers with other collision avoidance systems. ACAS Xa and Xo are intended for current TCAS users, and ACAS Xu is designed for UAS and other vehicles with new surveillance technologies and different performance characteristics.

The ACCS T³CAS, with ACAS Xu Version 2 software, was integrated on the Northrop Grumman Firebird Demonstrator, an optionally piloted aircraft. Both ACSS and Northrop Grumman also provided manned aircraft that flew predetermined collision encounter geometries with the Firebird Demonstrator.

As part of the ACAS Xu development, the FAA is also working with the European Organization for Civil Aviation Equipment (EUROCAE) on international safety standards.