Integration of UAS in existing air traffic management systems connotations and consequences

Abstract

The current airspace rules have evolved over a century of manned flight. This is not to say that they are ideal but they are known and all operators apply them. This paper examines the issues raised by integrating UAS in the existing ‘air traffic management systems’ and airspace, and, the connotations of the integration and the subsequent consequences for both manned and unmanned aircraft. ‘Integration’ means fitting in with the current operators in the airspace and with those users' rules and behaviors. It does not mean setting up UAS reservations, otherwise known as UAS Traffic Management; nor does it mean adding new rules and regulations that limit the existing manned aviation operations. An indication of the size of the problem in the USA is that there are 230,000 manned aircraft; fixed, wing, helicopters, gliders etc., but there are already 770,000 UAS registered with the FAA (not including those unregistered purchased on EBAY or ‘toy’ stores) So the UAS being integrated are three times more than manned, but the value of the manned aviation sector to the USA is 1.8% GDP and cannot be hazarded. So manned/unmanned integration must be well planned. Yet it is apparent from SESAR and NextGen that the current ATM systems and their ConOps are at their scalability limit adding more aircraft will lead to delays and potentially reduce safety. Even the definition of the airspace is being challenged. It is unclear whether the FAA actually has authority to regulate aircraft operations below 500ft or 400ft or 83ft dependent on which case law is used. Neither is it clear whether State or City laws have precedence over FAA regulation. If deliveries by ‘drone’ are a commercial use case, then not being able to descend below 83ft above ground is a significant limitation that cannot be overcome by throwing money. Existing manned operators are clear that at low level they are in Class G airspace where the Rules of the Air and Visual Flight Rules pertain. But UAS cannot fly Visual Flight Rules so they will fly ‘Detect and Avoid’. The Rules of the Air require a pecking order of aircraft type avoidance precedence based on seeing and identifying the aircraft type. UAS cannot ‘detect’ the aircraft type so cannot apply the Rules of the Air for example; the flight rules require that a Predator must avoid a hang glider but it cannot sense the other aircraft type so cannot obey the rules of the air. In mandatory IFR airspace the UAS will be required to follow IFR; one of the IFR regulations is on loss of communications an aircraft should follow its last clearance to destination; not loiter or have a ‘lost link procedure’. Can an IFR UAS that has lost its link to the ground station fly the remainder of the mission including fitting in with an arrival sequence? This paper proposes an approach that could allow the number of aircraft operating be raised by a factor of four and still be safe to operate. The approach fits with the proposed ConOps from SESAR and NextGen of using Trajectory Based Operations. All aircraft would be treated equally whether manned or unmanned but would also be required to follow the same ConOps. It is achievable as it considers that an aircraft is an aircraft regardless of whether it has a pilot on board, and the connotation is that all aircraft should be treated equally but the consequence is that they must all meet the same basic level of capability. The impact on UAS avionics architectures and operations are highlighted and are significant. UAS can be integrated into the current ATM airspace but it will require significant changes in both the UAS systems and the systems analysis approach.