Military & Aerospace

Airspace Control: Challenges and Way Ahead
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In the framework of international law, ‘sovereignty’ signifies the full right and power of a State to govern itself and its territory without any external interference. This legal right to exercise power, in the context of aviation, grants a State the ownership of its national airspace as well as the authority to exercise judicial, administrative and legislative powers within that airspace. The concept of airspace needs to be viewed against the backdrop of UN Convention on International Civil Aviation (Chicago Convention) which dates back to 1944, and had set into motion the formation of International Civil Aviation Organisation (ICAO) as a UN agency in 1947. The Convention’s first Article recognises that every State has complete and exclusive sovereignty over the airspace above its territory. It further defines territory of a State to be the land areas and territorial waters adjacent to them under the sovereignty, suzerainty, protection or mandate of the State.

The UN Convention on the Law of the Sea (UNCLOS) also impinges on airspace inasmuch as it differentiates between sovereign and international volumes of oceanic airspace where States may make laws and where States may not make universal laws respectively. Interestingly, neither the UNCLOS nor the Chicago Convention includes the terms ‘national airspace’ and ‘international airspace’ per se. It is significant to note that the Chicago Convention is binding only to civil aircraft and excludes from its ambit ‘State aircraft’ which are aircraft used for military, customs and police services. Article 3 of the Convention lays down some restrictions for the use of State aircraft overflying territory of another State and the underlying principle is with due regard to the safety of navigation of civil aircraft. However, there is no requirement for State aircraft to comply with civil requirements in international airspace although generally State aircraft voluntarily file flight plans in accordance with civil requirements.

With some States increasingly carrying out military and security operations far from their own territories, the problems of airspace control are extant challenges, to be studied, addressed and resolved before incidents like the shooting down of Ukranian International Airlines Flight 752 by Iranian military earlier this year, are repeated. Civil aviation and military aviation have their own peculiar challenges which get compounded where the two use the same airspace. This article looks at airspace control challenges in the current milieu.

Flexible Use of Airspace

As the medium of air is used by civil and military aircraft conjointly, airspace is rendered one continuum to be used optimally by all its users through accommodation of maximum requirements of both. However, the types of aircraft used, the safety philosophies, the training values and the manpower mindsets of civil and military personnel, are quite disparate. There is also the fact that civil aviation is driven by commercial (read revenue) considerations while military aviation has the more intangible concept of national security at its core. Their confluence thus tends towards tumult and disorderliness.

To this end, Flexible Use of Airspace (FUA) evolved as an airspace management concept implicit with a methodology of capacity management at its core. ICAO Doc 9750 (Global Air Navigation Plan), Doc 9426 (Air Traffic Services Planning Manual) and Circular 330-AN/189 (Civil/Military Cooperation in Air Traffic Management), provide the basis while other ICAO publications, for example, Annex 2 to the Convention on International Civil Aviation (Rules of The Air) and Annex 11 to the Convention (ATS Airspace Classifications) also impinge peripherally on the concept.

The US Special Use Airspace (SUA) programme and the ICAO FUA are essentially the same – endeavouring to make the best use of navigable airspace over the globe for requirements of States’ national defence, commercial and general aviation and public right to freedom of transit through it. Implementation of FUA through efficient civilian military co-ordination is seen as an enabler of traffic growth with ultimate benefit to the States’ economies. FUA permits both military and civil user to efficiently and effectively utilise the available airspace on sharing basis to gain optimum usage, thereby enhancing its capacity, which results in efficient operations. In Europe, the FUA Concept was introduced in March 1996 after development by civil and military representatives of the European Civil Aviation Conference (ECAC) States together with representatives of aircraft operators clubbing scheduled airlines, general aviation and business aviation. EUROCONTROL, a pan-European, civil-military organisation dedicated to supporting European aviation, sees FUA as a system that sees no differentiation between civil and military airspace; but as one continuum. Contiguous volumes of airspace are not seen as being constrained by national boundaries.

The FUA Concept has been developed at three levels of airspace management that correspond to civil/military co-ordination tasks with each level impinging on the others. The strategic level defines national airspace policy and establishment of pre-determined airspace structures, the pre-tactical level deals with day-to-day allocation of airspace according to user requirements while the tactical level facilitates real-time use of airspace allowing safe General Air Traffic operations that include flights conducted in accordance with ICAO rules and procedures, including military flights doing so and Operational Air Traffic, largely military traffic not complying with ICAO rules and procedures.

In 2013, a long standing need of FUA over Indian airspace was cleared by the government. While meeting the military needs as dictated by the rapidly changing nature of air warfare, the FUA was also perceived as beneficial from the point of view of saving fuel and reducing CO² emissions, largely due to the approval of direct routing between some city pairs; increase in passenger carriage capacity and reduced delays are other ultimate benefits to Indian civil aviation.

It is pertinent to note that most nations are justifiably very protective about parcels of national airspace which straddle assets to which national security concerns are attached. It is prudent to expect that the FUA concept will never embrace all airspace and that some national airspace will always remain military in nature. Understandably, progress in this area is a bit slow due to conflicting motivations of commercial interests and national security. However, in the realm of civil aviation, advances in aviation technologies are providing the thrust to overcome air space control challenges even as the volume of air traffic continues to increase at a rapid pace, with attendant changes in the tenor and texture of airspace control that are challenging.

Civil Aviation Initiatives

Perhaps the most significant initiative in the direction of countering the complexities of airspace control is the US Next Generation Air Transportation System (NextGen). It is steered by US Federal Aviation Administration (FAA) whose self-stated mission is, “to provide the safest, most efficient aerospace system in the world.” NextGen is essentially aimed at modernising the US air transportation system to make flying safer, more efficient and more predictable, and is one of the most ambitious infrastructure projects undertaken in the US. Its outstanding feature is that, instead of making incremental, minor upgrades to long-standing infrastructure, it seeks to implement major new technologies and capabilities into a modern National Airspace System (NAS). It is not one technology, product or goal, but a continual introduction of new technologies to improve air travel. In 2007, the FAA started implementing cutting-edge technologies, procedures and policies that benefit passengers, the aviation industry and the environment and plans to continue through 2025 and beyond. As NextGen moves forth, it is creating new interconnected systems that change and improve how NAS stakeholders navigate and communicate.

In terms of Air Traffic Control (ATC) technologies, Canada is ahead of the US even though Canadian air traffic is about a tenth of that of US airspace which has more than 44,000 flights a day. In 1996, Canada’s ATC system was privatised into a not-for-profit corporation known as NAV Canada which has demonstrated impressive capability to induct new technologies rapidly and a penchant for raising finance on the private market. The Canadian integrated air traffic management system known as NAVCANatm is now being used in Europe including in London, Australia and some States in the Middle East.

The challenges of airspace control over Europe have been accosted through the Single European Sky (SES) initiative launched by the European Commission in 2004 to reform the architecture of European Air Traffic Management (ATM). It proposes a legislative approach to meet future capacity and safety needs at a European rather than on a local level. Its key objectives are restructuring European airspace as a function of air traffic flows, creating additional capacity, and increasing the overall efficiency of the ATM system. Both Single European Sky ATM Research (SESAR) in the EU and NextGen in the US, are researching trajectory management methods. One of the interesting offshoots of this research is PureFlyt, the Flight Management System (FMS) developed by Thales, specifically designed to efficiently manage aircraft (on which it is fitted) in a connected aerospace ecosystem and in increasingly crowded skies. Implementing the concept of Initial 4D (I4D), it aims at improving the accuracy of flight in four dimensions, the fourth dimension being time. PureFlyt is expected to enter service (including as a retrofit) in 2024, and will enable more effectiveness in maintaining optimal distance between aircraft, particularly in the critical phases of departure and arrival from an airport.

Closer home, Seamless Skies is an initiative to bring harmonisation in air traffic management over Asian skies and create more efficient traffic flows over Asian airways. Unfortunately, very little progress has actually been made although the plan has not been shelved. Initiatives in the direction of improving situational awareness have been impressive and the disappearance of Malaysian Airlines flight MH370 in 2014 provided the much needed impetus to fitting every aircraft with equipment to provide its exact location in the airspace it is traversing to a ground station (or stations) automatically.

Automatic Dependant Surveillance-Broadcast (ADS-B) is the object of desire in this context. This is an aircraft mounted system in which on board equipment automatically broadcasts the precise location of the aircraft which is determined by Global Positioning System (GPS) via a digital data link. A suitable transmitter then broadcasts that unique position at rapid intervals, along with identity, altitude, velocity and other data. Dedicated ADS-B grounds stations receive the broadcasts and relay the information to air traffic control for precise tracking of the aircraft – without the need for a radar. ADS-B data is broadcast every half-second on a 1090MHz digital data link and contains flight identification and adequate information about its flight parameters to ensure that its passage through airspace is absolutely safe. The ability of a ground station to receive ADS-B signals depends on altitude, distance from the site and obstructing terrain and can sometimes exceed 460km. Effective January 01, this year, the US has already put into place a regulation for all aircraft flying in US-controlled airspace to have ADS-B on board. Other States are in the process of implementing ADS-B fitment. Once all aircraft are so equipped, a serious challenge to airspace control would have been almost eliminated. On some routes in India, ADS-B equipment is mandatory already while it is being made compulsory slowly on other routes.

GPS, run by the US Air Force (USAF) but used by almost every human being on the Earth daily, is a constellation of 31 satellites, each transmitting a radio signal towards the Earth continuously. Their positioning in space permits GPS-enabled receivers to receive four or more of those signals to allow triangulation of their position in three dimensions. That makes GPS an essential and indispensable element to navigation through airspace. However, with proliferation of space vehicles, the GPS satellites themselves are vulnerable to hard kills or critical disruptions. Moreover, the GPS signals themselves can be jammed and if the attack is substantially successful, results can be catastrophic for aerial platforms using GPS for navigation. This challenge to airspace control is being tackled by the next generation of GPS satellites – GPS III, being built by Lockheed Martin — which is projected to be three times more accurate and eight times more resistant to jamming and cyber attacks.

Emerging Challenges

As can be seen from the foregoing, there are initiatives afoot to ensure that the increasingly congested airspace used by civil and military aviation, is kept safe for flying through well established and constantly improved air traffic control system in place to track, monitor as well as continuously and seamlessly guide flights through that airspace. However, the rapid proliferation of Unmanned Aerial Vehicles (UAVs) or drones for civil and military purposes, is posing a new challenge to airspace control as they are small, carry negligible onboard equipment and are horrendously difficult to track comprehensively. Moreover, their numbers are alarmingly large and rising exponentially due to their low cost, immense commercial lure and easy availability.

An upsetting fact about drones is that there is really no distinction between civil and military use like in the case of airliners or business aircraft. Almost all drones are theoretically prone to use for military or terrorist purposes. There are programmes to find solutions to the problem of detecting and tracking small drones. US Defence Advanced Research Projects Agency (DARPA) is at the forefront with its Aerial Dragnet development programme which is primarily aimed to be a military one, but may produce products for civil use eventually to serve the purposes of airspace control. In the US, a Research Transition Team (RTT) has been set up between the federal agencies and industry to execute an initiative called Unmanned Aircraft System Traffic Management (UTM) which will not only manage traffic, but also carry out other complex tasks, including data exchange, software functions, infrastructure, supporting operations beyond visual line-of-sight and a lot more. The key areas include data exchange, information architecture, sense and avoid as also communication and navigation.

Urban Aerial Mobility (UAM), more fancifully referred to as air taxi, is another emerging challenge to airspace control especially to urban airspace. Movement of people and goods through the medium of air would serve to reduce congestion from crowded roads, but airspace would come under tremendous strain. Airbus, a leader in the global aerospace industry, has invested extensively in multiple UAM projects, including Vahana (a one-passenger EVTOL platform), Voom (on-demand helicopter booking platform) and City Airbus (a four-passenger EVTOL platform). Uber is already working on its Uber Elevate shared air transportation programme to begin in Dallas, Los Angeles and Melbourne, Australia, using small four-passenger Electrical Vertical Takeoff and Landing (eVTOL) vehicles. Uber plans to begin demonstration flights later this year and commercial operations in 2023. Volocopter, a German company, recently unveiled the world’s first air taxi Vertiport in Singapore for completely autonomous flight testing. Other companies including Amazon and Uber intend to use commercial drones for their home delivery services.

Mitigation of congestion at major airports will increasingly become a major concern as these programmes mature. The US is the leading edge of UAM and US National Aeronautics and Space Administration (NASA) recently introduced ATD-2 Integrated Arrival, Departure and Surface (IADS) Operations at Charlotte Douglas [North Carolina] and Las Vegas McCarran International Airport as part of its Airspace Technology Demonstration (ATD) project. ATD-2 integrates technologies already implemented by the FAA and the airline industry to streamline ground, arrival and departure procedures. The ultimate aim is to save fuel and time, reduce emissions, cut down surface congestion, minimise delays and of course, increase safety in a crowded urban airspace.

Another solution to emerging airspace control challenges is the Digitial Air Traffic Tower technology which aims at enhancing a controllers’ ability to maintain a comprehensive and detailed picture of the airspace around the airfield. A significant aspect is the use of a panoramic display – much like an aircraft’s Head-Up Display (HUD) which replicates the view out of a tower’s windows and enables detailed feeds from different sensors to be presented in the same windows, permitting controllers to more seamlessly integrate additional data sources into a single operational picture with enhanced ability to control airspace.

Military Control of Airspace

Command, Control, Communications, Computers and Intelligence (C4I) systems, supported by Information Technology or IT (the Computers and Communications part of C4I) provide the wherewithal for military decision making by a commander for accomplishment of a mission. One important capability that C4I systems provide commanders is situational awareness about the location and status of enemy and friendly forces. Airborne Warning and Control Systems (AWACS), Airborne Early Warning (AEW) and various types of UAVs have been the resources that have enabled control over battlefield airspace. Artificial Intelligence (AI) is helping develop and use right tools for control of airspace in the military domain. Battle Management System (BMS) is an expert rules-based system offering users or commanders comprehensive battlefield view with respect to target analysis, automated recommendations and awareness of the situation for the target objects. According to a 2019 study by Research Insights, an analytics and research company, the key players in the global BMS market are Saab AB, Rockwell Collins, Harris Corporation, BAE Systems PLC, Rolta India Limited, Leonardo SPA, Thales Group, Raytheon Company, Elbit Systems Ltd and General Dynamics Corporation.

US Department of Defence (DOD) is developing an Advanced Battlefield Management System (ABMS) based on drone, space and ground systems although it is still only at a software engineering concept stage and its final architecture is yet to be defined by the USAF. For the US Army, Northrop Grumman is working on the Integrated Air and Missile Defence (IAMD) Battle Command System (IBCS) programme which integrates available sensors to increase survivability by allowing air defence elements to have a broader view of airspace over the battlefield and will integrate data from different sensors into a single integrated air picture. Grumman, MBDA and Saab have successfully completed a joint, collaborative effort to demonstrate the ability to integrate MBDA’s Common Anti-air Modular Missile (CAMM) family and Saab’s Giraffe radar system family into IBCS. Thus IBCS represents a next generation, net-centric approach by integrating disparate radars and weapons to construct a far more effective IAMD enterprise. IBCS delivers a single integrated air picture with unprecedented accuracy and broadens surveillance and protection areas. With its open systems architecture, IBCS allows incorporation of current and future sensors and promises to be a useful handmaiden for military airspace control.

Swarming drones are a military challenge to airspace control. ‘Swarm intelligence’ promises to provide connectivity and autonomy to drone swarms. The former facilitates the seamless coming together of drones permitting them to intelligently ‘aggregate’ and ‘disaggregate’. However, in a drone swarm, each drone has only partial information of the operating environment and the other drones immediately around it. Therefore, communication between the component drones of a swarm is critical to the swarm’s mission and hence, jamming their communication links may be the solution to ridding airspace of interest from attacking swarms.

As an aside, is a site that provides a conflict zone and risk database freely to anyone who needs it giving all airspace risk warnings so that airlines and other aircraft operators can be forewarned of any risks to their flights due to air defence actions by nations involved in warlike situations across the globe.

Concluding Remarks

In the wake of President Donald Trump announcing the establishment of a Space Force, NATO heads of state jointly declared in December last year that space was now a ‘domain of operations’ – the fifth after land, sea, air and cyber. Technically speaking, this distension of air as a medium of war into space has also expanded airspace into aerospace and is closely related to the All Domain Operations concept of war fighting. Starting with Sputnik 1 in October 1957, there has been an increasing number of small and large objects being launched into space and placed in orbit around the Earth. The US Space Surveillance Network detects, tracks, catalogues and identifies artificial objects orbiting the Earth. Reportedly in June last year, the SSN data listed 44,336 objects including 8,558 satellites owned by 92 countries (including Bhutan!) according to, a site that tracks space objects in real time. This number is constantly rising, nay, accelerating. Orbits vary from 240km above earth to 36,200km. The arithmetic of the three dimensional volume of aerospace is literally of astronomical proportions.

Another dilemma in space is the demonstrated ability starting with a 2007 Chinese anti-satellite attack on its own satellite to destroy space objects physically. The task of aerospace control, implicit with monitoring, tracking and guidance of one nation’s space assets while protecting them from inadvertent as well as malafide hard and soft attacks, has become unimaginably complex and indeed an area of uncertainty. Undoubtedly, this would be a challenge to airspace or aerospace control that would be the most arduous to confront in the years to come.

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The views expressed are of the author and do not necessarily represent the opinions or policies of the Indian Defence Review.

About the Author

Gp Capt AK Sachdev

Director - Operations, EIH Ltd.

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