An Unmanned Aerial System (UAS) has three components:
- An autonomous or human-operated control system which is usually on the ground or a ship but may be on another airborne platform;
- An Unmanned Aerial Vehicle (UAV);
- A command and control (C2) system – sometimes referred to as a communication, command and control (C3) system – to link the two.
These systems include, but are not limited to, Remotely Piloted Air Systems (RPAS) in which the UAV is controlled by a ‘pilot’ using a radio data link from a remote location. UAS can also include an autonomously controlled UAV or, more likely, a semi autonomous UAV. In recent years, the tendency to refer to any UAV as a Drone has developed but the term is not universally considered appropriate.
UAVs can vary in size from those which can be hand launched to purpose built or adapted vehicles the size of conventional fixed or rotary wing aircraft.
The development of UAS
Military and other State use of UAS has developed rapidly since it began apace in the USA in the early 1990s and has utilised satellite communications and GNSS navigation to operate UAVs at very long distances from their controllers. However, well before this, the first recorded use of large UAVs was in 1935, when the British Royal Navy began using adapted DH82 Tiger Moth aircraft called ‘Queen Bees’ which were flown under radio control for gunnery target practice.
A total of 380 of these were built and used by both the Navy and the RAF before they were retired in 1947.
In recent years, fixed wing UAVs have been joined by increasing numbers of rotary and multi-rotor UAVs. As previously, the military has led the way in using UAVs and only more recently have they become, at the smaller size, accessible to civil users who were previously limited to the longstanding hobby activity of flying radio controlled model aircraft.
The civil applications of UAS
The recent rapid progress in extending the scope of military and State use of UAS has led to recognition of the very widespread potential for civil commercial applications of various UAS, the majority of which are small UAVs operating below the height above terrain normally used by manned aircraft or at least below about 1000 feet agl.
Many of these uses are now well established and include:
- Security surveillance
- Emergency response including SAR
- Facilitation of communications and broadcast
- Small package and bulk cargo transport
- Visual, spectral and thermal examination of structures
- Monitoring of linear network infrastructure such as railway tracks, power lines and pipelines
- Photography and cartographic survey
- Agricultural fertiliser and chemical application
- Aircraft external maintenance inspection
- Atmospheric research
UAS Operational Issues
The issues which have had to be addressed for this type of operation have centred on both the safety of other aircraft and issues of public (third party) safety and the protection of privacy.
The latter has been especially prominent due to the fact that many UAS applications involve the use of the UAV as a platform for a high definition camera.
The relatively small UAVs typically used are in contrast to the much larger range of UAV sizes which has collectively typified military use.
The development and use of Military UAS which has been so important in driving the scope and capability of these systems, especially the larger UAVs, has been possible because the airspace in which they have been used has been either permanently or temporarily segregated, with access by manned aircraft excluded or strictly controlled.
This has often reduced initial and continuing airworthiness standards considered acceptable for military operations to levels below those which would satisfy civil safety regulation requirements.
It has also limited the need for the sense and avoid technology which will be essential for operation of all but the smallest UAVs in shared non-segregated airspace if the risk of collision between aircraft and UAVs – or between UAVs – is to be adequately mitigated.
In this matter, the objective for civil RPAS is currently seen to be a demonstration of at least an equivalent level of risk to that to which manned aircraft are currently exposed. However, deciding what this level of safety is in operational terms outside controlled airspace has proved problematic.
The issue of permissions for commercial UAS to operate at low levels – typically below 400-500 feet agl – in non-segregated airspace has generally been associated with the complete prohibition of UAV entry into controlled airspace which extends to the surface or to any uncontrolled airspace to which access could interfere with aerodrome operations.
Such permissions have also generally addressed the risks of third party injury, undue invasion of privacy and operator training.
As a result of requirements for the latter, new training organisations dedicated to the training of RPAS operators, most of whom controlling civil UAVs do not have experience as a pilot of a manned aircraft, have appeared – and been embraced and approved by some regulatory authorities such as the UK CAA.
Operator training is also becoming an increasing focus for military and State users of RPAS, as system deployment increases in line with increasing task capability and the availability of former military pilots and navigators to act as RPAS operators diminishes.
Whilst the terms UAV/UAS and RPAS are of relatively recent origin, they have been retrospectively applied to the long-established leisure activity of flying of radio-controlled model aircraft within Visual Line Of Sight (VLOS).
It is this type of restricted UAV operation which is where current growth in both leisure and commercial use is taking place, but means to permit the more complex civil use of UAVs which can be controlled Beyond Visual Line of Sight (BVLOS) and/or safely within un-segregated controlled airspace are also being actively pursued
. Such operations are likely to require demonstrably resilient C2 systems and effective ‘Detect and Avoid’ (sometimes called ‘Sense and Avoid’) mechanisms.
It is widely recognised that the latter will need to deliver a level of safety equivalent to that achieved by manned aircraft. However, defining what that level of safety actually is within various classifications of airspace is as yet unresolved.
The two areas of safety regulatory oversight of UAS – operations and UAV airworthiness, are being overseen on a supra-national basis by the Joint Authorities for Rulemaking on Unmanned Systems (JARUS).
This body was established in 2007 and describes itself as “a group of experts from National Aviation Authorities (NAAs) and regional aviation safety organisations” which aims to provide guidance material to facilitate “a single set of technical, safety and operational requirements for the certification and safe integration of UAS into airspace and at aerodromes” and thereby enable each authority to write their own requirements whilst achieving cross-border harmonisation and avoiding duplication of effort. Founder Members include the FAA, the EASA and EUROCONTROL and members from around the world now represent the interests of 35 States, including both China and the Russian Federation. One of the many challenges for JARUS has been to consider the extent to which regulation of a UAS might be based on the size – however defined – of a UAV.
UAS Operational Safety Issues
The operational safety issues raised by UAS depend essentially on:
- the risk and potential consequences of mid-air collision with another UAV or a manned aircraft
- the risk of loss of control of a UAV
- the risk of intentional misuse of a UAV
- whether the use to which a UAV is put is Military/State, Commercial, Leisure or Hobby
These issues are the focus of the currently mixed picture between States on the most appropriate balance between regulatory requirements and their communication and the issue of guidance.
In some cases, prohibition is being applied to certain uses or classes of user pending the development of a comprehensive approach, and much of the commercial use of UAS is being controlled by ad hoc application to safety regulators such as the FAA or UK CAA for a uniquely-specified permission which is then issued on that basis.
So far, there are no internationally-recognised licensing or airworthiness certification systems for UAS operators and outside segregated airspace, only experimental engagement with the ATM system.
Efforts are beginning to be made to communicate both regulatory and non-regulatory guidance to leisure operators of very small UAVs but since their identity is not known, this has not been wholly successful. In some countries, publicising successful prosecutions for use of UAVs in breach of local regulations is also being used as a means to spread awareness.
In Europe, it is widely recognised that harmonised State Regulations right across the range of UAV sizes is highly desirable but the current arbitrary split is based on UAV weight. This is currently being used in Europe to distinguish between NAA and EASA regulatory competence – respectively ‘below 150 kg’ and ‘150 kg or more’.
This is now generally accepted to be an arbitrary distinction unsupported by evidence which is not necessarily significant in terms of the safety issues raised by UAS operations.
In particular, it has been recognised that the third party risks of UAV operation are not necessarily proportional to the weight or size of the UAV.
Another challenge is that leisure-use small UAVs everywhere are flown by two rather dissimilar types of operator.
The established group of model aircraft enthusiasts are mostly members of, or at least are content to take guidance from, a national body which oversees the safe and ‘reasonable’ conduct of their activity in liaison with the National Aviation Authority (NAA) and/or directly from the NAA.
This group of people have long demonstrated that their enthusiasm for what they do is almost always associated with their receptivity to guidance.
By contrast, it has become clear that the recent and rapidly growing number of other leisure users of small UAVs are interested as much in what they can do with a UAV – often fitted with a camera – as in the safe and ‘reasonable’ use of it and will have usually have no previous experience of aviation.
A situation similar to the new leisure users applies to the majority of commercial users of small UAVs, but this has so far generally been directly regulated with appropriate risk mitigation requiring at least the completion of sufficient operator training to be able to demonstrate a minimum level of competence.
Two leading manufacturers of remotely piloted aircraft systems are nearing the goal of certifying unmanned aerial systems (UAV) for operation in the same airspace with manned aircraft, thus removing a major barrier to entry for drones that restricted the operation of large drones over the populated areas in Europe, Canada, and the USA.
Elbit Systems of Israel and General Atomics Aeronautical Systems Inc. are the two forerunners in this field, followed by IAI and Northrop Grumman.
Until recently nations that acquired such drones for Medium Altitude Long Endurance (MALE) missions could operate them primarily in the under-developed regions of the third world, where the majority of air traffic is conducted at high altitude, leaving the medium and low altitude an unregulated open space.
MALE drones are regularly operated under special military permissions in Singapore, India, South Korea, across Central Asia and EuroAsia, parts of Latin America, Africa, Turkey, and the Middle East.
In contrast, Europe, and North America or other nations operating under the International Civil Aviation Organization (ICAO) rules, are inaccessible for drones, except for few areas reserved for drone experimentation and training.
Operation in such airspace with special permissions would require the implementation of “detect and avoid” anti-collision systems.
Two new drones – the SkyGuardian from General Atomics ASI (GA-ASI) and StarLiner from Elbit Systems are positioned to complete a complex certification process by the European Aviation Safety Agency and UK Military Airworthiness Authority (MAA), to enable drone operators to fly within the dense European airspace, almost everywhere a manned aircraft can.
On July 11, 2018 GA-ASI completed the first transatlantic crossing with the SkyGuardian MQ-9B unmanned aircraft, designed and built for the Royal Air Force ‘Protector RG MK1’ fleet.
The RAF has been operating the MQ-9 Reaper for ten years, flying over 100,000 flight hours, but could not operate the drone over the British Isles since the drone could not be certified as a safe aerial vehicle.
Both companies decided to tackle the problem head-on and test the authorities’ readiness to certify large drone platform counting on some European governments’ pressure to enable drone operations within the European airspace. Being ‘Certifiable’ means that all components, structures, avionics, software, procedures etc., are meeting civilian aviation standards.
While such standards are mandatory for the design of every manned aircraft, they were completely ignored during the development of unmanned platforms.
At present, ‘Certifiable’ provides customers with some assurance that their future drones will be allowed to operate in their national airspace, thus position military drone makers in an advantageous position vis-à-vis procurement programs in Europe and Canada, where tenders are expected to exclude, or at least recognize certification as a threshold for entries. It will also urge aviation authorities, setting the standards for future autonomous aviation.
Another drone that potentially meets the ICAO rules is the MQ-4C Triton High Altitude Long Endurance (HALE) drone from Northrop Grumman, the first drones of this class are now fielded with the US Navy and operate on maritime surveillance missions. Since those drones were fitted with anti-collision and de-icing systems to meet the requirements of the US Navy, to enable operations in the civil and international airspace, they could also be considered for operations over Europe.
A German request to buy four such systems was approved in April 2018, has been approved, but an order for such systems is still pending.