The U.S. Army has validated the design and functionality of a second-phase ground-based sense and avoid (GBSAA) radar system that will support training flights of MQ-1C Gray Eagle UAVs in unrestricted airspace beginning in 2014.

The Phase 2, Block 0 system that will serve as the baseline GBSAA system for monitoring Gray Eagles in flight was demonstrated in June at Dugway Proving Ground, Utah, site of an unmanned aircraft systems (UAS) testbed and the Army’s UAS Rapid Integration and Acceptance Center. The two-week demonstration covered several “vignettes” involving live RQ-7 Shadow and RQ-5 Hunter UAVs as well as simulated UAVs and intruder aircraft at Dugway. The testing also replicated the airspace over other military installations and used live and recorded air traffic data from Salt Lake City and Boston Logan airports, respectively.

The Army plans to fly General Atomics-built Gray Eagles from their base airfields through military Class D airspace to nearby test ranges for training purposes. The launch site in March 2014 will be Fort Hood, Texas, followed by Fort Riley, Kan.; Fort Stewart, Ga.; Fort Campbell, Ky.; and Fort Bragg, N.C. All five sites are slated to be equipped with the GBSAA system by 2015, according to the Army.

GBSAA block upgrades will enable the system to generate a recommended maneuver for a ground-based operator (GBO) to communicate to the UAV operator to avoid an intruder aircraft. “We are not air traffic control,” said Mary Ottman, Army deputy product manager of unmanned systems airspace integration concepts. “We’re not controlling everybody; we’re only controlling ourselves.” Ottman, who spoke on August 6 at the Unmanned Systems North America conference in Las Vegas, said the Block 0 system that will be fielded will provide the GBO with a display of nearby traffic color-coded to reflect the highest-priority potential conflicts. A Block 1 upgrade presents the operator with instructions for avoiding conflict.

Currently, the Army can operate UAVs in unrestricted airspace with a chase plane or within line of sight of a trained observer. It cannot fly UAVs at night. GBSAA, incorporating three-dimensional radar and other sensor inputs, data fusion and software algorithms for collision avoidance, is being developed as an alternate means of compliance with the Federal Aviation Administration’s Part 91.113 aircraft right-of-way rules, and as part of an overall solution that will include airborne sense-and-avoid technology developed by the Navy and Air Force.

The Army is the lead service for GBSAA within a Department of Defense UAS task force. The service developed and operated a prototype GBSAA system at the General Atomics flight-test facility in El Mirage, Calif., in April last year. That system has been deactivated and the testing has shifted to Dugway Proving Ground.