The latest variant of the American MQ-9 Reaper, the MQ-9B SkyGuardian, set a new endurance record flying 48.2 hours at altitudes between 7,800 meters (25,000 feet) and 11,000 meters (35,000 feet). More importantly new flight control software and hardware in SkyGuardian complies with strict air traffic control regulations that control the use of most European air space and until recently made it impossible for local or foreign military to fly UAVs in local airspace for any reason. Since a growing number of European armed forces were using these UAVs overseas in combat they faced a problem bringing them home and using them there. So solutions were sought and several were implemented and approved.
SkyGuardian has also been modified for longer endurance and operations at high altitudes (at least 40 hours in the air at 15,000 meters/50,000 feet) where there is less commercial air traffic. These mods involve a larger wing and construction with some lighter materials. Most importantly SkyGuardian comes equipped with “sense and avoid” technology that complies with European regulations. That also involves better resistance to lightning strikes but mainly it means using onboard flight control software that meets European flight rules.
Sense and avoid is a major problem worldwide although it is worse in Europe where the skies are more crowded and the regulations most strict. The U.S. Army was one of the leading developers of such sense and avoid systems because it puts more UAVs into the air than the air force and navy combined. The army developed a radar system (GBSAA or Ground-Based Sense And Avoid) to increase safety for UAVs operating in busy airspace. GBSAA is mainly a software system using existing radars to track UAVs and manned aircraft and alert UAV operators when their UAVs are too close to other aircraft (manned or unmanned). GBSAA can be also use transponders (which commercial aircraft have been using for a long time) and more flexible software. But the basic idea is to insure that UAV operators are no longer “blind” to what is in the air nearby. GBSAA had its first field test in 2013 and it was a success. The first GBSAA deployed in 2015 and five more bases will have it soon.
Systems like GBSAA are also in demand by potential civilian UAV users. Battlefields have much lower safety standards than civilian air space, what with all those artillery and mortar shells, plus the bullets and rockets. But civilian air space has a lot of small aircraft and helicopters, so UAVs are generally banned. GBSAA could change that and make battlefields safer as the UAV traffic becomes denser.
SkyGuardian used a sense and avoid system optimized for large, high-flying aircraft. That meant a transponder (meeting commercial aircraft standards) and flight control software that uses an onboard radar to monitor aircraft in front of the MQ-9B and the ability to comply with commercial flight control rules. This includes sharing all flight information with the ground controller and issuing alerts to the operator and local air traffic control systems if there is a problem. The MQ-9B operator would then intervene and speak with air traffic control as a pilot would to maneuver the MQ-9B out of the situation.