Sky structure

One of the basics of flexible integration of UAVs in the manned airspace is a harmonious correlation of the current sky structure and new concepts for drones.
AUGUST, 21 / 2019 / 5 MINUTES
Фото вышки в Örnsköldsvik
In accordance with the federal rules for the use of the airspace of the Russian Federation, three classes of airspace are defined: A, C and G.
The highest altitude — Class A airspace — has a lower boundary at around 8100 m. Here flights are performed only by instruments (IFR) and separation is used. All flights are subject to prior approval by ATC and are provided with mandatory dispatch support.
Class C is defined below 8100 m. Its boundaries can vary for different zones and areas. Here, the movement of the aircraft is carried out by instruments (IFR) or by the rules of visual flights (VFR), separation is applied. All flights are provided with mandatory dispatch support, and the availability of constant two-way radio communication with air traffic control services is mandatory. In addition, you must have permission to use the airspace, and at an altitude below 3050 m there is a speed limit (not more than 450 km/h).
Finally, the lower airspace is Class G. Its upper boundary varies from 300 m to 4,500 m depending on geographic location. Class G allows both instrument flights and visual flights. Here, most often, GA flies, or "light" aviation, and in the future — unmanned aerial systems (UAS). Separation and dispatching are not required, however, if necessary, aircraft can be provided with flight information services. In the event that flights are carried out on instruments, then constant two-way radio communication with air traffic control services is mandatory. Special permission to fly in class G is not required.
Drone integration
The classification of the airspace of the Russian Federation does not contradict the European concept of integration of unmanned aerial vehicles UAS ATM Integration. In Russia, a similar project, which is based on multilateration technologies (multi-position monitoring systems, MPSN), is at the stage of active development.
The UAS ATM Integration concept defines two new categories of airspace: VLL — very low level airspace and VHL — very high level airspace. Since unmanned aerial vehicles (UAV) are difficult to categorize because of their diversity, seven flight classes are additionally introduced.
In the lower airspace VLL (up to 150 m), UAV flights will be carried out, relating to four classes at once. This is a large part of private flights, commercial operations, etc. The boundaries of the very high airspace VHL are at around 20,000 m. For this zone, only one UAV flight class is defined.
For the rest of the airspace between VLL and VHL, which is 19 850 m, two more classes are reserved. In this airspace, commercial aviation flies, and in some cases — GA. In this regard, UAV flights must be carried out according to strict rules: mandatory visibility to air traffic control systems, the presence of collision avoidance technologies compatible with similar systems on manned ships (PVS).
Below is an illustration comparing the current boundaries of the classes of the RF Air Force (left) and the classes described in the UAT ATM Integration concept (right) for UAS. The schedule does not intentionally present the areas of airports, since UAS flights are not performed there.
Everything has its place
What tasks do UAVs solve in the air spaces described above? Let us first consider flights at an altitude of up to 150 m.
Within the framework of class 1 — flights in the line of sight, three subclasses are defined: A1, A2 and A3.
For subclass A1, flights are permissible in areas with low air traffic, away from airfields and other prohibited areas. The height limit is 50 m.
UAV flights of no higher than 120 m (subclass A2) should be carried out far from mass crowds, while preliminary drone pilots should pass special tests online.
Flights of larger UAVs (also not higher than 120 m) weighing no more than 25 kg (subclass A3) are allowed for pilots who have passed theoretical and practical exams; at the same time, geofencing technology should be implemented to prevent violations of the perimeters of forbidden zones.
The so-called "free flights" (class 2) are intended for operations that are not amenable to advance planning, primarily search and rescue operations. Medium and long range flights (class 3) are provided for monitoring power lines, railways, and other long-distance operations. UAV flights in the framework of classes 2 and 3 can be performed both within and outside the line of sight. At the same time, UAVs should be visible to surveillance equipment, and for such operations a flight plan must be submitted. The use of a common altitude measuring system is mandatory, and drones must support the possibility of self-separation.
The last class in airspace up to 150 m is class 4. The class is intended for rare and highly specialized operations, including flights in areas prohibited for UAVs.
Commercial aircraft fly at altitudes from 150 m to 20,000 m (classes 5 and 6), so here the drones are equipped with two-way communication with the dispatcher, have the ability to withstand safe intervals from the manned aircrafts and can avoid collisions using DAA systems. Flights in classes 5 and 6 are operated in accordance with IFR or IFR rules and will comply with the requirements for communication, navigation and surveillance (CNS) systems.
UAV flights at an altitude of 20,000 m and above (class 7) offer compliance with the requirements of classes 5 and 6, the airspace of which will have to be crossed by UAVs in this case. For class 7 operations, drones similar to those previously presented by Facebook or Google can be used.
Security foundation
Classification of airspace, types of UAS and types of operations performed provide the necessary basis for future safe joint flights between manned aircrafts and UAS. The presence of many types of UAVs and the diversity of their capabilities require a detailed and structured approach to the organization of air traffic with uniform transparent rules.
At present, in Russia, the issue of creating a concept for the integration of BWS into the airspace is relevant. The solution to this most important task will enable all stakeholders (UAV, hardware and software manufacturers, operators, regulatory authorities) to form a unified vision of the future industry and then determine the strategic course of UAS development.
And this issue needs to be addressed promptly. Indeed, today in the world technologies are already being worked out everywhere that make it possible to implement such concepts in practice. In particular, DAA systems are tested, as well as technologies that make UAVs visible to air traffic control devices and other air traffic participants (ADS-B 1090ES, 4G/5G, FLARM). Geofencing systems are being actively developed and implemented (similar to how it was done at Gatwig Airport, in London). Flying prototypes of transport UAVs and much more are being created.
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