The introduction of new CASs results in a multiplication of the number of different systems in the airspace. And this is not without consequences. During ACAS Xa integration tests, though the coordination was working perfectly, it was noted that the performances of TCAS were degraded. This highlighted the fact that CASs need not only to be able to coordinate but they also need to be interoperable.
As George Bernard Shaw once said “Both the optimists and the pessimists contribute to the society. The optimist invents the aeroplane, and the pessimist the parachute”. All over the world, numerous initiatives and demonstrations have shown the multiple benefits of drone operations, that is the optimists’ work. Now the pessimists are also at work to prevent malicious use of drones.
According to the ICAO’s RPAS manual, a full Detect And Avoid (DAA) system must prevent collisions with: conflicting traffic, terrain and obstacles, hazardous meteorological conditions, ground operations and other airborne hazards (such as wake turbulence, birds and volcanic ash). However, most of the existing efforts focus on DAA for conflicting traffic as it represent the highest risk, letting aside the rest of the hazards. Especially in the case of ACAS Xu which design and evaluations focus on conflicting traffic avoidance.
Recently, Trustwave applied for a patent describing how to integrate existing terrain and weather avoidance systems with ACAS Xu. The goal being to inhibit collision avoidance maneuvers which could direct the RPAS into terrain or hazardous weather, and to account for these in the computation of Remain Well Clear (RWC) maneuvers.
The efficiency of such a system remains to be demonstrated, yet it is one step closer to a complete DAA system.
Current aircraft safety nets will form the basis of RPAS safety systems. According to its definition, a safety net is not supposed to be a primary way of achieving a safety task.