7.4 Research Paper: Request for Proposal

In this activity, you will develop a response to the following:

Natural disasters such as tornados, hurricanes, and wildfires have a devastating impact on communities where these events occur. Lives are lost, citizens are injured, and infrastructure and property are destroyed. In the aftermath resources are limited, while the response and recovery is hampered by reduced communications and infrastructure damage. Based on this scenario use these high-level base requirements to propose a series of derived/low-level requirements for the design of a UAS down to the element level (e.g., air vehicle element, command & control [C2], payload, data-link [communications], and support equipment) to support response and recovery efforts.

Ensure you include applicable test requirements to verify the system will work as proposed and an associated schedule to perform the required phases of development (e.g., system development, ground testing, and in-flight testing). In addition, develop an overview to identify associated design considerations and decisions for your derived requirements. You are encouraged to locate and examine commercially-off-the-shelf (COTS) components to determine capability associated with the UAS elements for the derived requirements and testing strategy.

Request for Proposal

            Natural disasters have a massive impact on the areas in which the disaster occurs. During natural disasters, lives are lost, people are hurt, and homes, buildings, and infrastructure are damaged or destroyed. In the aftermath of these disasters, response and recovery can be slowed by the limited number of resources available to aid those in need. This request for proposal shall review the major base requirements of transportability, air vehicle elements, and payload for a UAV that is designed for search and rescue operations. During natural disasters, people can easily get lost in all the chaos; in the aftermath, search and rescue teams will come to the aid of these people. By allowing search and rescue teams to utilize unmanned aircraft, search and rescue efforts will become more efficient and areas that cannot be easily reached by ground search and rescue teams can be further explored for missing people. The UAV being developed for this proposal will allow search and rescue personnel to deliver lifesaving materials to the lost people if needed. The UAV will be a quadrotor design that will allow the UAV to takeoff and landing vertically. This function will also allow the operator to thoroughly search an area hit by a natural disaster. The time frame for this UAV will be 2 years in development.

Transportability:

1.1  The entire system (including all elements of the UAV) shall be transportable in a hard, protective case that will weigh less than 50 lbs enabling one person to carry the UAV.

1.2  The hardened case shall have various compartments dedicated for all components for the UAV.

1.3  The hardened case shall be one single case which will enable the entire UAV/control system to be carried at once.

1.4  The hardened case shall be designed to be picked up and carried by a single person or rolled on the ground via a handle with wheels on the case.

1.5  The hardened case shall be designed to withstand a fall from a height of 5 feet with minimal damage to the case.

1.6  The hardened case shall be designed to protect the UAV by absorbing the shock from a fall of 5 feet.

Air Vehicle Elements

1.1  Shall be capable of flight up to 500 feet in altitude above ground level.

1.1.1        The UAV shall climb at a rate of 2 meters per second.

1.1.2        The UAV shall be capable of descending at a rate of 1.5 meters per second.

1.1.3        The UAV shall be capable of operating in temperatures ranging from 0° to 40° C

1.1.4        The UAV shall be capable of flight in sustained winds up to 25 mph.

1.1.5        The UAV shall utilize satellite GPS for precise movements. 

1.2  Shall be capable of sustained flight (at loiter speed) in excess of one hour.

1.2.1        Battery life for the UAV shall exceed two hours of flight time due to a hydrogen fuel cell.

1.2.2        After sustained flight at loiter speeds, the UAV shall return to the operator.

1.3  Shall be capable of covering an operational radius of one mile.

1.3.1        The UAV shall have the ability to operate at distances up to 3 miles.

1.3.2        The UAV shall calculate the distance and fuel required to return to the operator.

1.4  Shall be deployable and on station (i.e., in air over mission area) in less than 15 minutes.

1.4.1    The UAV shall have each component that can easily snap into place.

1.4.2    UAV components shall easily be taken out of the hardened case due to ergonomic fittings for the components.

1.4.3    Shall have a maximum cruising speed of 44 mph depending on wind conditions.

1.5  Shall be capable of manual and autonomous operation.

1.5.1        The operator shall control the UAV when necessary.

1.5.2        The operator shall use the autonomous functions when necessary.

1.5.3        Autonomous operation shall be programed into the control station when manual operations are not being utilized.

1.5.4        Specific flight patterns shall be integrated into the systems on the UAV for thorough coverage of an area.

1.6  Shall provide capture of telemetry, including altitude, magnetic heading, latitude/longitude

position, and orientation (i.e., pitch, roll, and yaw).

1.6.1        UAV data shall be sent back to the operator for review of the flight.

1.6.2        UAV shall utilize GPS to transmit information about the flight back to the operator.

1.7  Shall provide power to payload, telemetry sensors, and data- link

1.7.1        The UAV shall utilize the electrical systems on board to power the payload, telemetry, and data link sensors.

1.7.2        The UAV shall have built in redundancies in the event that a function on the UAV ceases to operate properly.

1.8  Shall provide capability to orbit (i.e., fly in circular pattern around) or hover over an object of interest.

1.8.1        The UAV shall utilize GPS to hold a specific position based on latitude/longitude coordinates.

1.8.2        The UAV shall be capable of holding any altitude up to 500 feet set by the operator.

1.8.3        The UAV shall utilize GPS to fly specific search grids that will allow the operator to search an area carefully.

1.8.4        The operator shall have the ability to choose where to have the UAV orbit based on a specific position in the air.

Support Equipment:

1.1  Design shall identify any support equipment required to support operation

1.1.1    To support the operation, SAR personnel shall require rope to attach to the UAV in the event that a person is found and in need of medicine, water, or food.

1.1.2    SAR personnel shall require a lightweight basket to carry important supplies if a person is found and ground teams cannot reach the person immediately.

1.1.3    SAR personnel shall require a thermal imaging camera for operations at night.

1.1.4    SAR personnel shall require multiple hydrogen fuel cells for the safe operation of the UAV on long flights.

Testing Requirements:

            Tests will be completed to determine if the functions described above are testable or verifiable. Commercial off the shelf (COTS) components shall be used in the development of this UAV. In order to reduce potential development costs, simulation software will be used to test the abilities of the UAV first. After simulation data indicates the UAV will operate based on the design requirements, the UAV will be tested in person. Each requirement will be rigorously tested to determine if the UAV will be able to aid search and rescue personnel during SAR operations.

1. Transportability Testing

1.1  Storage of UAV components.

1.1.1        The UAV components will be placed into the hardened case cut outs to determine if the UAV will fit snugly into the case.

1.1.2        The case will be closed to determine if the case will close properly without damaging any of the components of the UAV.

1.1.3        The ground control unit will also be placed into the hardened case to determine if spacing is an issue.

1.2   Durability of hardened case.

1.2.1        The hardened case will be dropped from heights varying from 1 foot to 5 feet.

1.2.2        Once the case has been dropped from these heights, the case will be opened to determine if the components of the UAV have not been damaged.

1.2.3        The outside of the case will be looked at carefully to determine how much damage has occurred at each height.

1.2.4        All the components of the UAV will be placed inside the case to determine if the case is less than 50 pounds.

1.2.5        Determine if the case can easily be carried based on its shape and determine if the wheels on the case roll smoothly when applicable.

Air Vehicle Element

2.1 Flight Characteristics

2.1.1    The UAV shall be flown at varying altitudes up to 500 feet to ensure the UAV is                          airworthy.

2.1.2    The UAV will be flown at the minimum and maximum operating temperatures to ensure the UAV will not fail at temperatures near these extremes.

2.1.3    The max cruising, ascent, and descent speeds will be tested in normal flight conditions. The UAV will also be tested on days that are windy. The maximum operation in wind speeds of 25 mph shall be tested.

2.1.4    The hydrogen power cell will be tested to ensure the UAV can fly for one hour loitering and up to one more hour of standard flight.

2.1.5    The UAV will be flown out to 3 miles to determine if the UAV will warn the operator of the maximum distance being achieved.

2.1.6    The communications between the UAV and the ground control unit will be tested during the long range flight.

2.1.7    Multiple tests will be ran to determine that the UAV can be deployed and in the air within 15 minutes. If the UAV cannot be assembled in less than 15 minutes, a different design based on a collapsible UAV will need to be researched.

2.1.8    The UAV operator shall test the manual operation capabilities of the UAV. The operator will also put the UAV into an autonomous flight mode to test the flight grip capabilities of the UAV. The proper pitch, roll, and yaw controls will be tested during this time.

2.1.9    Determine if the UAV can send flight data, images, and video back to the operator.

2.1.10 The UAV will be placed into an orbit around a specific point. At this time, the UAV will be tested to determine if the UAV can hold a position based on latitude and longitude. The ability of the UAV to hold altitude will be tested, and flight grid patterns will also be tested again during this time.

2.1.11 The hydrogen fuel cells will be checked carefully for proper operation.

3. Support Equipment

3.1 Required Support Equipment

3.1.1    For intended search and rescue operations, a rope shall be attached to the UAV. At this time, the payload characteristics will be determined. The UAV will be designed to carry small payloads in the event that a missing person is found but ground search and rescue personnel cannot reach the person.

3.1.2    A lightweight metal basket will be attached to the UAV. The UAV will be flown at varying speeds and altitudes to ensure the UAV can carry the required payloads.

3.1.3    Materials such as food, water, medicine, clothes, or even lifejackets will be placed inside the basket of the UAV. The UAV will be flown at various speeds and altitudes to ensure the UAV can fly with light payloads.

3.1.4    The camera on the UAV will be tested to ensure clear videos and pictures can be taken during flight and at loiter speeds.

3.1.5    The thermal imaging camera shall be tested at night to ensure proper operation.

The Development Process

            The 10-Phase Waterfall Method will be utilized as a starting point for the development of this UAV. This development process would be the most efficient process because during phases 5, 6, and 7, the testing of the UAV could be completed as these phases concern testing and development of the UAV. This would allow a smooth transition to the last phases of the waterfall method which are certification, production, and support.

            To ensure an acceptable level of safety in the operation of any airborne system, including UAV systems, the airworthiness of the system and its safe usage of the airspace     in which it operates must be addressed at an early stage in the design, and pursued in the    development and operational trial phases (Austin, 2010, pg. 223). 

By using the waterfall method, the UAV should be completed in a reasonable amount of time (1 year) and ready for use in search and rescue operations. The specimen test, prototype build and test, and the development of the UAV (modifications) will take the longest amount of time to complete as the developer wants to ensure that each function of the UAV is testable and verifiable. Phases 1-4 will be completed in 4 months, phases 5-8 will be completed in 5 months, and phases 8-10 will be completed in 3 months.

            The UAV being created for search and rescue missions has been designed to carry light payloads of water, food, clothes, or medical supplies in the event that ground SAR personnel cannot reach a person directly affected by a natural disaster. The UAV has also been designed for search and rescue missions when a person is lost or missing. The standard camera will be utilized during the day for SAR operations and the optional thermal camera can be used at night during missions. The UAV being designed must be created to carry small payloads for SAR missions. This is why basic derived requirements for support equipment must be tested. If the UAV cannot carry small payloads, SAR personnel will not get full usage out of the UAV. A hydrogen fuel cell has been selected for use instead of batteries of gas because of the flight times that are achievable. A hydrogen fuel cell may be more efficient than gas or batteries, and it could be lighter than having to carry gas. Unlike a battery that has a short flight time, the hydrogen fuel cell intended for use of this UAV should allow the UAV to remain in the air for 2 hours. This would prevent the operator from having to fly the UAV back for gas or a battery replacement. The requirements for this UAV will ensure that the UAV is more than capable for usage during search and rescue operations for missing people or for delivering small loads of supplies to a person who cannot immediately be reached by ground personnel. The GPS grid patterns will allow the operator to manually or autonomously follow sweeping patterns that will allow the operator to thoroughly search and area. The UAV will also be developed to warn the operator of altitude limitations, distance limitations, and when the hydrogen fuel cell is running low. The computer systems within the UAV should allow the UAV to return to the operator autonomously based on latitude and longitude. All the design considerations, testing, modifications, certification, and production of the UAV shall be completed in a steady manner to ensure that each step is completed correctly.

References

Austin, R. (2010). Unmanned aircraft systems: UAVS design, development, and deployment.    Chichester, U.K: John Wiley & Sons Ltd.

UAS Mission

What are the design and implementation of a specific UAS mission (military, or civil)? Determine a specific subject mission, consider public use or emergency services as law enforcement, medical, rescue or fire related mission sets. In your response:

• Identify and discuss the particular mission you are highlighting for a UAS
• Select three platforms capable of performing the mission and obtain an appropriate reference citation for each
• Discuss any considerations relative to the mission and if they correlate to the performance of any related mission execution tasks
• Identify the benefits and challenges associated with performing the particular UAS mission you are highlighting
• Identify and discuss at least two legal and or ethical challenges to the specific mission you are highlighting

UAS Mission

            Unmanned aerial systems (UAS) have continuously proven that there are many missions that can be completed in a more efficient manner than manned aircraft or by man on the ground. With the number of UAS increasing within the United States, it is inevitable that unmanned aerial vehicles (UAVs) will become part of the National Airspace System (NAS) for commercial usage. One important field that is utilizing UAVs is search and rescue operations. Search and rescue missions can be dangerous for people moving through varying terrains. There will also be instances in which search and rescue personnel cannot move through an area due to obstacles blocking the path. Manned aircraft have been utilized for years during search and rescue missions, but these operations can be incredibly expensive and time consuming. Due to the size of manned aircraft, if multiple aircraft are utilized, there must be distance between the aircraft. However, with the small size of UAVs, many aircraft can be flown in an area searching for a lost person. UAVs are expendable, cost less to operate than manned aircraft, do not put pilots at risk, and can cover large areas in short amounts of time.

            UAVs cost significantly less than traditional fixed wing aircraft and helicopters. Small UAVs are much more maneuverable and the video and images taken from the camera can be sent to an analytical team for review. Small UAVs that are being utilized for search and rescue operations have fewer operational risks and do not directly put the pilot in danger during flight. UAVs can survey large amounts of land in short periods of time and software has been developed that allows the operator to track the flight paths already taken by the UAV. This will prevent the operator from flying the same paths that have already been searched. In addition to this software, the UAV normally has enough flight time to scan large areas, especially if the operator flies the UAV in a sweeping pattern. While ground crews can also be used during search and rescue operations, a UAV can complete SAR operations quickly whereas ground crews could take hours to find a missing person. 

            Many UAVs can be utilized for search and rescue operations. For the purposes of this research paper, the three UAVs that will be discussed are the DJI Phantom, the Delta FW70 Fixed Wing UAV, and the Titan X8 heavy lift UAV. The DJI Phantom has become a very popular UAV for hobbyists. Due to the battery life, the stability of the UAV, and the clear resolution of the camera, the Phantom has many uses beyond aerial photography. As of November 3, 2016, DJI and DroneSAR have come together to develop a search and rescue application for first responders to utilized during operations. The search and rescue application can stream live videos and images from a standard or thermal camera to the incident command center (DJI and DroneSAR, 2016). The software for the application has the ability to tag specific areas of interest or the coordinates of a lost person which will allow SAR personnel to locate the missing person. The application also allows the operator to see the flight path of the UAV so that all patterns are recorded and logged and areas will not be missed (DJI and DroneSAR, 2016). The Phantom 3 has a max flight speed of 35 mph, utilizes GPS during flight, can ascend at 11 mph, can descend at 7 mph, and has a max service ceiling of 19685 feet above sea level (Phantom 3 Standard, n.d.).

            Another UAV that can be utilized for search and rescue operations is the Delta-FW70. This UAV is 70 inches and has a delta wing configuration made from dense foam. This UAV is durable and lightweight which means there will be longer flight times, shorter landing distances, gentle touch downs, and easier maneuvers (UAV Delta-FW70, n.d.). The FW70 can carry up to five pounds and the long wingspan makes flying in gusty conditions much easier when compared to other smaller UAVs. The FW70 was created to be an aerial remote sensing and mapping platform; there are 4 payload bays and this feature allows for an oversized camera that can take crystal clear pictures (UAV Delta FW70, n.d.). The Delta Wing FW70 is a great candidate for search and rescue operations. Unlike vertical takeoff and landing (VTOL) UAVs, the FW70 can cover a range of 600 acres in an hour on a single battery. “It is fully capable of autonomous flight and includes a “Fly By Wire” mode, as well as software for GPS, autopilot, mission planning, and a telemetry system” (UAV Delta FW70, n.d., para. 6). With this technology, the FW70 can cover large areas while sending the images and videos back to a command center, allowing teams to analyze the information for missing persons.

            The final candidate for search and rescue operations is the xDrone Titan X8 Heavy Lift UAV. The Titan X8 is a heavy lift UAV capable of carrying up to 6.5 kg (14.33 pounds) and can fly at 14 m/s (31 mph) (xDrones Titan X8, n.d.).  The wonderful aspect of this UAV is that the Titan X8 can be used by search and rescue teams to carry lifesaving items such as life vests in the event that people are in danger outdoors. The payload levels also allow things such as food and water to be carried to people in need. The Titan X8 utilizes GPS for easier flight and has an advanced on board camera that can rotate 360 degrees for continuous views of the surroundings. This function would be great to have during a search and rescue operation due to the ability to completely search an area carefully. The Titan X8 can easily be broken down and stored into a transport box. The Titan X8 can travel up to 3300 feet without any delay between the UAV and the control station (xDrone Titan X8, n.d.).

            The big considerations for UAV usage during search and rescue operations will be the weather. Manned aircraft can fly in gusty conditions while small UAVs can easily be blown around by strong winds. Strong winds can make a search and rescue operation difficult because the camera feed may be difficult to view. With manned aircraft, gusty winds will make flight difficult, but manned aircraft can handle the gusts better than a small UAV. Another advantage that manned aircraft have over UAVs is the payload that can be carried on board. While the Titan X8 can carry a payload up to 14 pounds, a manned helicopter can carry more but could be in an area that prevents landings. However, UAVs have the advantage of being smaller which means landing sites will be easier to reach. The search and rescue teams could also deploy multiple UAVs to carry vital supplies to a person in danger. Multiple UAVs would also make the search for a missing person much easier. Overall, UAVs can prove to be marvelous tools for search and rescue operations due to their small size, ability to carry payloads, battery life, and the costs of UAV purchase compared to fuel for manned flight. While there are challenges that will be faced such as weather, communications problems, and the ability to carry small payloads, when multiple UAVs are operated during search and rescue operations, missing people could be found much faster than traditional manned flight.

            UAVs are not without their legal and ethical challenges. One potential legal and ethical issue with search and rescue personnel utilizing UAVs for SAR operations is the footage that is captured while searching for missing people. There could be legal repercussions for uploading UAV footage because it could potentially expose personal, sensitive, or graphic images (Hodapp, 2015). People are already worried about their privacy with manned aircraft in the air. With UAVs increasing in drastically, more people are likely to worry about the levels of privacy when UAV footage is easily obtainable. Another legal issue that must be addressed in the near future is altitude restrictions for UAVs, particularly during search and rescue operations. Current regulations state that UAVs shall not exceed an altitude greater than 400 feet AGL. What will happen if SAR personnel need a UAV to operate at altitudes greater than 400 feet? Will the FAA write new rules that allow law enforcement and SAR personnel to exceed the 400 foot altitude restriction in the event of an emergency? There will also be issues that arise if the UAV must fly beyond the line of sight of the operator. Current regulations require that UAVs be operated within line of sight due to the lack of sense and avoid technology in the computer systems of the UAVs. If the operator or SAR personnel cannot reach a person in trouble, the UAV may need to be flown beyond the line of sight of the operator. If this occurs, does the operator need the permission of the FAA to fly higher than 400 feet and operate the UAV beyond the line of sight? These questions will need to be addressed in the future in order to get the full benefits from UAV usage for search and rescue operations.

References

DJI And DroneSAR Bring Search And Rescue App To First Responders. (2016, November 3).           Retrieved from http://www.dji.com/newsroom/news/dji-and-dronesar-bring-search-and-rescue-app-to-first-responders

Hodapp, P. (2015, December 15). Search and Rescue Teams Aim to Save Lives with Drones.             Retrieved from http://makezine.com/2015/12/15/search-and-rescue-teams-aim-to-save-lives-off-the-shelf-drones/

Phantom 3 Standard - Specs, FAQ, manual, video tutorials and DJI GO - DJI. (n.d.). Retrieved           from https://www.dji.com/phantom-3-standard/info

UAV Delta-FW70 Fixed-Wing UAV. (n.d.). Retrieved from http://www.hse-   uav.com/delta_fw70_fixed_wing_uav.htm

xDrones Titan X8 Heavy Lift (RTF). (n.d.). Retrieved from http://www.dslrpros.com/dslrpros-titan-x8.html

UAS in the NAS

UAS in the NAS

Part 1

            Detect, sense, and avoid technology is still in early development for unmanned aerial vehicles (UAVs). The absence of detect, sense, and avoid in current UAVs will undoubtedly lead to accidents both on the ground and in the National Airspace System (NAS). Due to the absence of detect, sense, and avoid technology, other technologies must be utilized to separate manned and unmanned aircraft. Safety has always been a concern in the aviation industry, but many of the regulations have been written in blood. With UAVs becoming increasing popular in the civilian sector, hobbyists and businesses are utilizing UAVs in many different ways. With the number of UAVs increasing at a dramatic rate, new regulations will need to be developed to ensure the safety of the aviation industry.

            There are several options available that could be utilized to reduce the risks of UAVs interacting with manned aircraft. First and foremost, the Federal Aviation Administration (FAA) should continue to develop and establish operator certification requirements. It is critical that UAV operators know certification requirements and airspace rules concerning the usage of UAVs. The FAA should assess the capabilities of UAVs. There are many kinds of UAVs; altitudes, speeds, communication abilities, and flight times will vary greatly depending on the class of UAV. An assessment of the capabilities of UAVs while also utilizing ground crews and ATC could help the FAA narrow down new regulations. The next option is to spend time and money creating detect, sense, and avoid technology. With this technology, UAVs will be able to “see” obstructions and other aircraft. Finally, current technologies such as ADS-B and TCAS could be implemented into UAVs in order to separate manned and unmanned aircraft.

Part 2

            There are five group classifications for UAVs. Groups 1 and 2 are micro and mini UAVs. These UAVs are likely to be operated via visual flight rules (VFR). If micro and mini UAVs are being operated within a line of sight, there would not necessarily be a need for detect, sense, and avoid technology. However, due to limitations with human eyes, the brain can distort the exact position of the UAV when another aircraft is nearby. Spatial disorientation becomes an issue with the UAV operator when the UAV moves out to a distance beyond what the operator can see. When a UAV moves out of the line of sight of the flight crew, the responsibility of sensing and avoiding cannot be assumed by the flight crew (Prats. Delgado, Ramirez, Royo, & Pastor, 2012). With these issues in mind, other support systems will be required to ensure the safety of the flight (Prats, et al., 2012).

            In order to assure that separation of aircraft can be assured, there are several factors that must be considered; flight rules, airspace class, the flight phase, the performance of the navigation systems, and the air traffic control surveillance means (Prats, et al., 2012). Groups 3 through 5 include tactical, MALE (medium altitude long endurance), and HALE (high altitude long endurance) UAVs. These UAVs fly regional, continental, and intercontinental routes and can fly from the ground up to 60,000 ft. Groups 3, 4, and 5 operate in all classes of airspace within the NAS. While small UAVs generally do not have the power to handle the integration of detect, sense, and avoid technology, larger UAVs such as the ones within groups 3 through 5 should be able to handle the required technology to sense obstacles and other aircraft. Technology that could be implemented include ADS-B, ACAS (autonomous collision avoidance system) and on-board radar (Prats, et al., 2012). Until micro and mini UAVs can be equipped with detect, sense, and avoid technology (which will require a lot of power and will reduce flight times), these small UAVs are likely to be restricted to line of sight operations.

Part 3

            There are several systems currently being utilized by manned aircraft that could be implemented into unmanned aircraft. These systems include ADS-B, ACAS, cameras, and radar. Cameras have been utilized by manned aircraft for many years. Unmanned aircraft have also utilized cameras, especially during times of war. Cameras can allow operators to see everything in front of the UAV and with new cameras having the ability to zoom in close to the ground, cameras will continue to be used during flight operations. ADS-B gives pilots real time information on air traffic, weather, and flight information services (FAA, n.d.). Safety and efficiency will improve as ADS-B is implemented into more aircraft. If UAVs are equipped with ADS-B, it is possible that the technology can be adjusted to give the operator real time updates on air traffic, weather, and flight information. UAVs must be developed to handle this technology before it is implemented. ACAS was developed to reduce the risk of mid-air collisions (Airborne Collision Avoidance System, n.d.). ACAS should enhance the awareness of the operator in relation to other aircraft within the same airspace. In 2016, the U.S. Army completed a test on a new system called Ground Based Sense and Avoid. This radar system should allow UAVs to fly within the NAS while also meeting FAA regulations. This radar system would allow the operator to fly the UAV out of sight while monitoring other aircraft and potential hazards during flight (Iriarte, 2016).

References

Airborne Collision Avoidance System (ACAS). (n.d.). Retrieved from             http://www.skybrary.aero/index.php/Airborne_Collision_Avoidance_System_(ACAS)

Federal Aviation Administration (n.d.). Next Generation Air Transportation System (NextGen).   Retrieved from https://www.faa.gov/nextgen/programs/adsb/

Iriarte , M. (2016, May 16). U.S Army completes UAS radar-based sense & avoid system test.     Retrieved from http://mil-embedded.com/news/u-s-army-completes-uas-radar-based-          sense-avoid-system-test/

Prats, X., Delgado, L., Ramirez, J., Royo, P., & Pastor, E. (2012). Requirements, Issues, and        Challenges for Sense and Avoid in Unmanned Aircraft Systems. Journal Of Aircraft,        49(3), 677-687. doi:DOI: 10.2514/1.C031606