Unmanned Aerial Systems (UAS) are becoming more popular day by day due to ease of availability and low cost. Hobbyist has contributed a lot in demonstrating various capabilities. UAS – “an unmanned aircraft that can navigate autonomously or remotely operated, without human control or beyond line of sight”. In this webinar role, the importance and limitation of such vehicles will be presented. We are aware that UAS is used worldwide for security from the border to internal security. The size of these UAS varies from submeter to full size aircraft. Research is towards shrinking the size further for indoor applications. Mission capability depends on payload capacity and endurance and this directly governs the size of the vehicle. UAS are enabling systems, the effectiveness of such a system will depend on the payload and mission capabilities. Few applications are Inspection of terrain, pipelines, utilities, buildings, etc., surveillance of road traffic, the crowd (big festivals), etc., Disaster and crisis management, search and rescue, Firefighting, Communications relay, VIP security, etc. UAS development and procurement must match with the security forces’ requirements. A few of the critical requirements are 1) Ease of use – Security person may not have the flying skill and the system shall have the capability to translate gestures to vehicle motion. When forward motion or any other motion like sideways or upward demanded using the joystick, an on-board system must convert these inputs to the desired motion. Many times, he/she may be interested in a particular target and once identified, the system shall track and provide required information 2) Easy to deploy system – Availability of open space for deployment is dependent on the scenario. Limited space is available especially in urban areas, maybe from a rooftop or open space of 20 x 20 m or less. Whereas in forest open space may be available, may not have a good surface for operation. Vehicles must have the capability to take off and land from such a constrained space. 3) Safety – These systems are likely to be used over the urban environment and must be safe to operate i.e. reliability must be high and must be robust towards any hacking. 4) Easy to integrate system – Internal security has to respond quickly to assess the situation and take decisions, it is important that such systems can be deployed as quickly as possible and reach the final destination. Keeping this in view, systems must be modular and can be integrated and deployed quickly on demand. Onboard sensors and communication networks must integrate with existing network seamlessly so that information can be shared easily. 5) Reasonable range – Systems are expected to work in urban areas and also in a forest area. In the case of urban areas range requirements may not be high as compared to forest areas. 6) Reasonable endurance – In urban scenarios endurance of 30 minutes may be adequate, but if more time is required then multiple vehicles can be used. In forest areas where resources are limited then higher endurance is preferred. Increasing endurance beyond a limit will increase the size of the vehicle and it will impact the operation from constrained space. 7) Mission flexibility – Urban security is a dynamic environment; mission may change on the move. The mission could be monitoring a location to chasing a target in a clutter of high-rise buildings. The system shall be capable of handling a variety of missions and change on demand. UAS can be classified as a) Fixed wing type and b) Hovering type. Fixed wing type UAS looks like conventional aircraft. These are highly suitable for high speed (upto 100 km/hr), long endurance, long range, etc. These can be made to hover but are not efficient in this role. Very useful for outdoor applications. Such a vehicle can be designed for vertical take-off and landing also. Hovering type UAS are multi-rotors and highly suitable for missions requiring to stay over one location. These vehicles have lesser forward speed as compared to fixed wing UAS. These are heavier but compact. Multirotor vehicles of six or eight rotors are capable of handling failures and make it safer; an important aspect from a safety point of view. These vehicles are highly suitable for indoor missions. UAS is going to be part of standard equipment for internal security. It is not possible to have a universal UAS for all the requirements. The modular design of UAS can help in carrying a variety of payloads. It is important to understand the mission’s need and constraints for the right selection. Future operations will involve multiple UAS, which can cover a large area for quick assessment. UAS is also becoming a potent weapon. The capability of UAS depends on the sensors and computing capability. With more sensors and computing power UAS are becoming smarter and human intervention is only required for very critical decisions. Alternate ways of powering the UAS is gaining momentum, which will enhance the endurance and range substantially.