Defence Industry

Mini-UAV to Aerospace: AD solutions to tackle Multi-Dimensional Air Threat
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Issue Net Edition | Date : 01 Jan , 2019

Various Unmanned Aerial Vehicles. Pictured are (front to back, left to right) RQ-11A Raven, Evolution, Dragon Eye, NASA FLIC, Arcturus T-15, Skylark, Tern, RQ-2B Pioneer, and Neptune.

Unmanned Aerial Vehicles (UAVs), also known as drones, are aircraft that do not carry any crew, but rather, are operated remotely by human operators, or autonomously via pre-programmed software or robots. UAVs vary widely in size and capacity, and have become increasingly prevalent. Their use has increased exponentially over the last decade for a broad range of applications, including cartography and mapping, inspection of remote power lines and pipelines, delivery services, telephone communications relay, police surveillance, tfc monitoring, border patrolling and recce, and emergency and disaster monitoring.

The use of mini-UAVs has increased exponentially over the last decade for a broad range of applications. The recent commercial availability of a new generation of small UAVs has emphasised the growing threat posed by these machines. There is a need for reviewing the security threats posed by mini-UAVs in areas such as terrorist attacks, illegal surveillance and recce, smuggling, electronic snooping, and mid-air collisions. The categories of mini-UAV intrusions in terms of intention and level of sophistication of the operators vary and thus keeping in view these mini-UAVs there is a need to formulate AD solutions for these multi-dimensional air threats.

Classification of Drones / UAVs. Terms like Drone, Remotely Piloted Vehicle (RPV),Remotely Piloted Aircrafts (RPA), UAV and Unmanned Aerial System (UAS) are the different nomenclature for the unmanned aircraft and have been use indifferent times but, all these terms mean the same. Secondly, there is no one standard when it comes to the classification of RPA’s. These can be classified by various parameters such as their size, endurance and range, maximum altitude, wing loading, engine type and power and thrust load. Since the study pertains to the counter measures against the RPA’s threat, the size and altitude of operation and speed would be the relevant factors for consideration. UAVs may be classified according to their size as follows :-

  • Very Small UAVs

     – Micro or Nano UAVs.

     – Mini UAVs.

  • Small UAVs.
  • Medium UAVs.
  • Large UAVs.

Very Small UAVs Micro and mini UAVs are the smallest in UAV technology with dimensions ranging from the size of a large insect to 30-50 cm long. These drones can fly at low altitudes that are below 300 meters. These micro and mini UAVs can carry little and lighter things such as listening and recording devices. Transmitters and cameras can also be carried by mini UAVs. Micro UAVs are smaller as compared to mini UAVs. The wt of the mini UAVs is less than 30 kgs and is best suited for commercial applications. Security agencies can use these for spying etc. Some commonly used mini-UAVs are as shown in Fig.

Easy Availability The fact that even small payloads can cause significant damage may lead to the conclusion that the most likely threat may occur from mini-UAVs. The most worrisome sit stems from model ac, where uncontrolled access to the knowledge, skills, and equipment required for mini-UAV assembly exists. Modelers are currently able to assemble vehicles with capabilities that used to be achievable only by professional teams. Not only are production-run accessories and separate parts such as engines, radio controls, servos, flights tab system, and GPS receivers currently available commercially, but a wide spectrum of ready-to-fly aircraft kit models are on the market. Some models require experience in piloting, but other aircraft that are simple and stable in flight are produced specifically for beginners. Therefore, relatively simple designs that are stable in flight may be used. UAV control and delivery to a target is a more complex task, but this task is not beyond power of nonprofessionals. The most imp element-prep of an aerial vehicle for a terrorist attack, includingassembly and tests-can be done legally, because such activity is not regulated or cont.

Mini-UAV as an Air Threat

From a mil perspective, UAVs, which can be recoverable or expendable, are generally used to op in dangerous or hostile territories, without endangering the operators. It is employed for surveillance and recce, info collection, detection of mines, and for combat purposes. UAVs hold many attractions for the mil. They are generally smaller, lighter and cheaper as compared to manned aerial vehicles as they do not need equipment to support a crew. UAVs can also be used for many hours in a stretch, while switching operators. The recent commercial availability of a new generation of small UAVs, often quad-copters or some other form of rotorcraft, has emphasised the growing threat posed by these machines. These UAVs can be easily purchased over the internet and can carry a payload of up to a few kgs. They are cheap, easy to fly and small enough to evade traditional security surveillance. A recreational UAV costing a few hundred dollars can be turned into an aerial equivalent of an improvised explosive device (IED), or be equipped with a cam and data downlink to become a spy UAV.

Security Threats On 25 Jan 2015, a small UAVs, Quad-copter which weighed about two pounds, op by a hobbyist crashed in White House at around 3 a.m. after its operator lost its cont. The White House radar system which is designed to detect flying objects like planes, missiles and large drones failed to pick up a small drone. As per a recent media report in India during past two years, there has been three sightings of drones near civil aircrafts. On 28 Jan 17, a serious near miss was reported by a pilot of Go Air aircraft which while approaching to land at Mumbai airport spotted a drone flying  at 12000 ft AGL horizontally separated from the civil flight  by just 2 km. This is potentially a dangerous flight  safetysit which mortally risked the life of the air passengers. No. of similar near collisions has been reported by International Air Tpt Association (IATA) worldwide between manned aircraft with drones. Nearly 100 UAV sightings are reported every month by the manned aircraft in their vicinity. Hence, flight  safety is a major  concern with unregulated UAV flying .

Mini-UAVs as a Potent Wpn There are innumerable ways in which a Mini-UAV can be used as a wpn.

  • Comb Wpns. An attacker could use a UAV to spray a weaponised chemical or biological agent over a crowd of people.
  • Target Designation. An operator could also use a UAV to reconnoitertargets for attack.
  • Surveillance. To monitor the actions of indls or law enforcement.
  • Smuggling. To smuggle illicit material, usually across borders or into prisons.
  • Electronic Snooping. Mini-UAVs can also be used for electronic snooping. At the Black Hat security conference held in Singapore, SensePost unveiled its Snoopy mini-UAV, which can steal data from unsuspecting smartphone users. The mini-UAV uses the company’s software, which is installed on a Computer attached to a UAV. The code can be used to hack smartphones and steal personal data without the user’s knowledge. This method could be used to particular effect in a crowded environment where many people have their cell phones auto searching for Wi-Fi networks.
  • Destruction of Aerial Targets. Pilots have expressed concern regarding the proliferation of commercially available small UAVs. If a UAV got into the engine of an aeroplane, it could stop the engine. Heptr pilots have reported several near-miss incidents with UAVs.
  • Jamming. Jamming of electronic devices.
  • Misc.

     –  Public Nuisance.

     –  Infringement of privacy of a person.

     –  IED/ Explosives.

     –  Electronic Attack

Advantages to Terrorist for Mini-UAV as a Potent Wpn. A set of advantages that make UAVs attractive to terrorists as a potent wpn are:-

  • Possibility to attack targets that are difficult to reach by land.
  • Possibility of carrying out a wide-scale attack aimed at inflicting a maximum death rate on a population.
  • Covertness of attack prep and flexibility in choice of a UAV launch site.
  • Possibility of achieving a long rg and acceptable accuracy with relatively inexpensive and increasingly available tech.
  • Poor effectiveness of existing air defences against targets such as low-flying UAVs.
  • Relative cost effectiveness of UAVs as compared with ballistic msls and manned airplanes.
  • Possibility of achieving a strong psychological effect by scaring people and putting pressure on politicians.
  • Possibility of achieving a strong psychological effect by remaining incognito.

AD Solutions to Multi-Dimensional Air Threats

After having a brief over view of the mini-UAV emerging as a potent threat and considering the above threat along with the existing air threats, there is a need to look at AD solutions for multi-dimensional air threats. The solution must encompass comps from the Air Force also with the overall AD responsibility remaining with the Air Force. Jtplg ,coord and synergy between the tri-services is essential for the overall AD of the nation.

Some of the solutions against mini-UAVs being in vogue in the developed nations are as under:-

  • Geofencing.
  • Radar Detection System.
  • Acoustic Sensing.
  • RF Emission Sensing.
  • EO Sensing.
  • Command Link Jamming and Appropriation.
  • Spoofing.


Commercial UAV manufacturers can play a key role by implementing GNSS-enforced geofences within their system that prevent their UAVs from being flown within exclusion zones around airports, sports stadiums, government buildings, mil bases and other security-sensitive sites. For example, DJI, one of the biggest UAV manufacturers, has embedded geofencing software in its UAVs that prevents them from flying  over thousands of sites worldwide where UAV op is illegal. This would be an effective mitigation step for UAV intrusions from unsophisticated operators. However, sophisticated operators could hack the software to disable the geofencing.

Detection System

(a) RadarDetection System. Existing air surveillance radar system are ineffective against mini-UAVs as they are developed to detect large aerial platforms moving at high speeds. As mini-UAVs fly at similar speeds and alts to birds, the two could be indistinguishable from each other. For high-risk events and known appearances of high-risk personnel, it may be necessary to bring in radars that have the fidelity to detect such small objects, such as the Blighter system developed by Plextek, and operators trained to distinguish between birds and mini-UAVs. Further complicating matters, to avoid radar detection, mini-UAVs may be built using poorly-radar-reflective materials and fly below the alt of 100 ft.

(b) Acoustic Sensing Acoustic sensors op by identifying the distinct noise made by the motors that drive the propellers of UAVs. Drone-Shield’s acoustic sensor was designed to provide high detection rates with low false alarms. It contains a database of common UAV acoustic signatures so that false alarms are reduced (e.g., lawn mowers and leaf blowers) and in many cases the type of UAV is also included in the alert. This system is being used by law enforcement officers in the US to enforce “no UAV zones”. A significant advantage of acoustic sensing is that is that it has low cost, even when implemented as a network of sensing devices placed around the protection perimeter.

(c) Radio Frequency (RF) Emission Sensing. UAVs typically send data back to their controller through a wireless data link. Using a directional antenna or a network of synchronisedgroundstations, such RF emissions can be detected and located. In order to be economical and offer rapid detection, the system must have some knowledge of the emission centre frequency and bandwidth, which are regulated for commercial UAVs. Drone Labs’ DD610AR UAV detection system employs RF emission sensing of a UAV’s command and data links to identify the coordinates of the UAV and its operator, and the unique identifier of the UAV, which can be used to prove that a particular incursion was done using a specific UAV. However, RF emission sensing can be easily evaded by sophisticated operators by maint radio silence.

(d) Electro-Optical (EO) Sensing. EO sensors in the form of optical and thermal cams can be quite effective at detecting UAVs. Dedrone’s Drone Tracker, which combines optical and thermal cams, can be used to form an EO sensing network to incr the chances of detecting a UAV. However, optical cams would have a difficult time distinguishing birds from UAVs. By utilizing Cmptr algorithms that look at flight  patterns, it is expected that a bird will fly a more random pattern than a UAV would. However, this notion fails in a place where birds glide, such as seagulls, which ride wind currents and stay at a steady level, and this fools optical system. Furthermore, hobbyist UAVs are mostly made of plastic and use electric motors, and thus, do not produce a lot of heat. Thermal cams would more likely detect a bird a UAV in most cases.

Electronic Defence

(a)  Command Link Jamming and Appropriation. Modern commercial UAVs are control by one or more wireless links to the operator’s control equipment. Traditional radio control (RC) controllers are still used as a backup means of control even for UAVs capable of a high degree of autonomy. These controllers send low-level commands to the autopilot system, or directly to the UAV’s motors or servos that actuate the UAV’s control surfaces. Jamming a UAV’ command link could effectively eliminate the ability of the UAV operator to conduct accurate targeting within the denied area. Command link appropriation could be used to take control of a mini-UAV. However, to appropriate the command link, the defender would need first need to determine the communications protocol, channel (from a potentially largeNo. of channels and code being used. Furthermore, the command link could be encrypted.

(b)  Global Navigation Satellite System (GNSS) Jamming and Spoofing.Virtually all modern commercial UAVs capable of autonomous flight  are navigated using GNSS satellites. Civilian GNSS signals are weak, rendering them susceptible to jamming, and unencrypted and unauthenticated, rendering them susceptible to spoofing. The defender could take advantage of the weak security of GNSS to confuse or command the mini-UAV.GNSS jamming would force attackers to op either using line-of-sight (LOS) RC control, or non-GNSS autonomous navigation. LOS control exposes the operator to visual detection and recognition, and can be denied by command link jamming.

Kinetic Defefence

Commercial UAVs are in gen fragile in the face of hard-contact kinetic attacks, such as small guided missiles, cannon-fired smart munitions, lasers and firearms. However, in urban environments, where attacks are more likely, law enforcement and mil will be averse to shooting UAVs down because any project used may cause collateral damage when it returns to the ground.


The tools and tac used by the terrorist organisations in the twenty first century are showing signs of shifting focus from the predictable form of terrorism to a form where modern tech is being used intelligently. Infotech based tools and modern communicationsystem are being emp by terrorists to improvise the existing forms of threat. Terrorists are found using new tech to their advantage while involving themselves in maritime, aerial, cyberor few other forms of terrorism.

The present international system in a rapidly changing world order is characterised by multivalence, interdependence and political cooperation. In the present system, no particular country or forum can ensure global security alone. The structure of the international system is not only changing rapidly but the challenges are also evolving very fast. For a better world, it is essential to resort to a pluralistic security order based on a cooperative approach to security.

Till date the world has witnessed terrorists usingaerialform of terrorism with some success. At the same time, the counter terrorism mechanisms employed by states are found gaining success. Such measures appear to have deterred the terrorist groups and have also succeeded in averting some major  plans of the terrorist groups to cause damage. However, with easy availability of hardware required to build an UAV or a toy plane the possibility exists that the terrorist gps could opt for new techs to effectaerialterrorism. This is not to say that the terrorists would discontinue with the techs used all these years for action attacks such asaerialattacks which cause mass casualties.

Terrorist groups still resort to such terror means in future in order to produce destruction in the form of life and property of catastrophic magnitude and to send a political message. They could try to find the unconventional ways to defeat the counter terrorism apparatus devised by nation states in this regard. In view of this, it is essential to strengthen the intelligence gathering mechanisms. More importantly, there is a need to comprehend the likely possibility of attacks by using the mini-UAVs or toy planes in developing counter terrorism strategies.

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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

Major Kevin Fernandez

commissioned into an Air Defence Missile Regiment in 2007. An alumnus of Cadets Training Wing, MCEME, Secunderabad, the officer has excelled in major professional courses and has been an instructor in Army Air Defence College.

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