UAS Integration in the NAS via NextGEN and Human Factors Issues

           NextGEN is a new system that is being implemented by the FAA in 2018 that will be an end to end aircraft controller that uses advanced algorithms that optimize not only flight routes, but also ground taxi procedures and possible unmanned aerial system (UAS) integration into national airspace (NAS) (Faa,2016). The system utilizes new hardware at the ATC level as well as new aircraft based systems called ADS-B (Automatic Dependent Surveillance- Broadcast). ADS-B utilizes satellite navigational aids to determine precise data about an aircraft’s position, speed, direction, altitude, and planned route and sends it to a corresponding air traffic controller agency. This information is integrated into a model that contains all aircraft flying in NAS. NextGEN takes all the precise data and uses advanced algorithms to optimize traffic, taxing, and route planning better than any human can (MacNeil, 2015). The communication between the controlling agency and aircraft is also able to provide weather data, traffic data, and important alerts like notice to airmen in the local area. Overall, the system will make the skies safer, increase pilot situational awareness, and save billions in fuel costs and environmental impacts due to efficient routing (FAA, 2016).

            One of the biggest issues facing current FAA policy is related to the integration of UAS into NAS. The current issue is that UASs cannot “see and avoid” according to the regulations set forth by the FAA. Additionally, UASs can lose link, which can cause unpredictable and uncontrolled flight within NAS. These two factors provide major safety hurtles for the integration of UAS into NAS. In order to ameliorate these issues, companies have been working to build airborne sense and avoid systems to increase safety, reduce pilot error, and increase trust amongst both general public and FAA. The DJI Phantom 4 is one of the newest UASs offered by DJI and provides one of the most well integrated and well-designed sense and avoid systems to come standard in any commercial UAS (DJI Inc., 2016). The issue with this system is that is helps keep the UAS clear of obstacles, but it’s not robust enough to provide the type of sense and avoid ability the FAA desires in NAS. NextGEN may provide solution to many off the sense and avoid issues associated with UAS flight due to its ability to monitor, predict, and deconflict flight of all aircraft. Another positive aspect to the use of NextGEN for UAS integration is that it standardizes UAS sense and avoid equipment, and methodologies. One major human factor issue that effects the integration of UASs into NAS has to do with the lack of operator training, certification, and licensing (Al Shibli, 2015). Due to the fact that current regulations have minimal requirements for training and certification, getting the quickly growing population of UAS operators to understand, participate, and coordinate with NextGEN requirements may be the hardest challenge.

            Another complicating factor for UAS integration has to do with lost link situations. If UAS integration does rely on ADS-B and NextGEN integration, there will be three separate possibilities for lost link. The aircraft could lose link with the controlling agency, the aircraft could lose link with the operator, or the controlling agency could lose link with the operator. These three separate scenarios could quickly cause many of the safety parameters offered for NextGEN to quickly disappear. This could be even more problematic when it occurs in busy airspace. Similar to what happens when pilots lose communications, there are many crew coordination steps that need to take place quickly that are not typical in order to account for the emergency situation. If untrained or minimally trained UAS operators experience a lost link, it may be even more dangerous due to their lack of training and standardization. Overall, UAS integration into NAS offers complex problems ranging from pilot training and standardization, to aircraft equipment and capabilities.                  

References

Al Shibli, M. (2015). Towards global unification of UAS standardization: Regulations, systems, airworthiness, aerospace control, operation, crew licensing and training.International Journal of Unmanned Systems Engineering., 3(2), 32-74. doi:http://dx.doi.org/10.14323/ijuseng.2015.7

DJI Inc. (2016). Phantom 4 -  DJI's smartest flying camera ever. Retrieved December 06, 2016, from http://www.dji.com/phantom-4

FAA. (2016). Next Generation Air Transportation System (NextGen). Retrieved December 06, 2016, from https://www.faa.gov/nextgen/aspx

MacNeil, J. (2015, June 3). Air Traffic Services Brief -- Automatic Dependent Surveillance-Broadcast (ADS-B). Retrieved December 06, 2016, from https://www.aopa.org/advocacy/advocacy-briefs/air-traffic-services-brief-automatic-dependent-surveillance-broadcast-ads-b  

Request for Proposal - Hurricane Response UAS Design

Mission

The mission for the request for proposal that relates to hurricane damage and insurance claim collection via UAS. After large hurricanes, infrastructure often is limited, damaged to roads and pathways is limited due to fallen trees and power and communications networks are often limited if not completely destroyed.  In order to facilitate quick insurance claims, the ability to gather photographs immediately after the hurricane is vital. Not only with his data help insurance adjusters, but it could also augment a governmental response to the damage by helping predict and plan required resources and support. In order to create a system capable of accomplishing this mission, many parts of the system can come from Commercial Off the Shelf (COTS) products. The majority of the design effort will go into ruggedizing both the air vehicle as well as ground control station in addition to finding ways to power both the air vehicle and ground station without a reliable power source. The entire process from design and testing should take no longer than one year.

Derived Requirements

1.                  Transportability

1.1      Transportation case weight

1.1.1        Transportation case shall be authorized for checked baggage on airline.

1.1.2        Transportation case shall fit in sedan trunk

1.1.3        Transportation case shall be man portable (50LBS or less)

1.2   Transportation case as charger

1.2.1        Transportation case shall serve as charging station for air vehicle.

1.2.2        Transportation case shall serve as charging station for GCS.

1.3      Transportation case ruggedness

1.3.1        Transportation case shall be waterproof per IP68 rating.

1.3.2        Transportation case shall be drop proof from 5 feet.

1.3.3        Transportation case shall be dustproof per IP68 rating.

2.                  Data-link

2.1  Data-link frequency

      2.1.1 Data-link shall not interfere with emergency rescue communications.

      2.1.2 Data-link shall communicate without external network assistance (no LTE).

2.1.3 Data-link shall be resistant to interface from external influence.

2.1.4 Data-link shall be encrypted.

2.2   Data-link distance

      2.2.1 Data-link shall extend to at least 2 miles.

      2.2.2 Data-link shall be line of sight only.

3. Ground Support Equipment

3.1   Power Generation

      3.1.1 Power generation shall be from external generator (gasoline).

      3.1.2 Power generation shall be from 12VDC (car charger).

      3.1.3 Power generation shall be from solar panels.

      3.1.4 Power generation shall be adjustable between gen/vehicle/solar via simple switch.          

3.2   Image processing

      3.2.1 Image processing shall be done off site.

      3.2.2 Image processing shall be transmitted via cellular network

      3.2.3 Image processing shall be transmitted via satellite network

      3.2.4 Image processing shall be transmitted via WIFI

      3.2.5 Image processing shall automatically transmit via lowest cost network available. 

3.3  On-site maintenance

      3.3.1 On-site maintenance package shall support operations for one-week mission

      3.3.2 On-site maintenance package shall fit inside transportation case

      3.3.3 On-site maintenance package shall provide common spares for one-week mission

      3.3.4 On-site maintenance package shall include common tools for one-week mission

Testing Requirements:    

1.                  Transportability

1.2      Transportation case weight

1.2.1        Check complete transportation case with airline common carrier

1.2.2        Place complete transportation case in trunk of typical sedan 

1.2.3        Weight complete transportation case to determine if under 50 pounds.

1.2   Transportation case as charger

1.3.4        Conduct charging operations via transportation case for air vehicle 

1.3.5        Conduct charging operations via transportation case for GCS 

1.4      Transportation case ruggedness

1.4.1        Submerge transportation case in 1 meter of water for 30 minutes then inspect.

1.4.2        Drop transportation case from 5 feet then inspect for damage.

1.4.3        Expose transportation case to dust for 30 minutes then inspect.

2.                  Data-link

2.1  Data-link frequency

      2.1.1 Operate data-link within close proximity of fire department and police department.

      2.1.2 Operate data-link in a location that does not have LTE network.

2.1.3 Operate data-link in a location that is exposed to exposed high voltage powerlines.  

2.1.4 Attempt to intercept and exploit encrypted data-link

2.2   Data-link distance

      2.2.1 Operate data-link past 2 miles and check for signal loss.  

      2.2.2 Operate data-link beyond line of sight and check for signal loss.  

3.         Ground Support Equipment

3.1   Power Generation

      3.1.1 Power system via gasoline generator and attempt a full charge cycle.

      3.1.2 Power system via 12VDV car port and attempt a full charge cycle.

      3.1.3 Power system via solar panels and attempt a full charge cycle.

      3.1.4 Swap power source during charging cycle and check for proper switching.            

3.2   Image processing

      3.2.1 Send data to offsite location for processing.  

      3.2.2 Send data to offsite location for processing via cellular network.  

      3.2.3 Send data to offsite location for processing via satellite network

      3.2.4 Send data to offsite location for processing via WIFI

      3.2.5 While sending data check for proper network swap according to net availability    

3.3  On-site maintenance

      3.3.1 Operate the system for a week with no external maintenance support.

      3.3.2 Pack the maintenance package into transportation case and ensure compliance.  

      3.3.3 Operate the system for a week with no external maintenance part support

      3.3.4 Operate the system for a week with no external maintenance tool support

             

Development Process and Timeline

             The method of development for this system will required multiple teams to work with both uniquely new designs as well as modify COTS components. Due to the fact that most components will not need to be designed from scratch the process should be slightly quicker. The entire timeline of all 5 phases will be approximately 12 months from concept design to production. One of the key processes during all phases of development is the requirement for an overarching systems engineer to ensure system integration is occurring continuously. Ensuring the components are subject to phased testing and validation would assist in ensuring development was both on time and in compliance with requirements through the entire design process (Sadraey, 2010). In regards to the phases of development the will be broken down as follows:

Phase 1: Concept Design- Build conceptual solution to above requirements. (2 month)  

Phase 2: Preliminary Design- Determine what COTS components can be used and integrate and design new and unique components as per the requirements above. (2 months)

Phase 3: Detail Design-Teams design production ready systems that integrate both COTS and non-COTS components and integrate into total system design plan. (3 months)    

Phase 4: Test and Evaluation- Utilize the testing requirements above in order to ensure sub-system integration between teams is conducted to standard.  Selection of test sites and procedures will be accomplished.  (2 month)

Phase 5: Production- Selection of production site, marketing, and distribution will be considered. (3 months)

Testing Strategies: Due to the heavy reliance of both ground support equipment and power generation components, the testing strategies of this system will focus on the integration of all the major components of this system. In order to test the system properly, the key will be finding a location that is representative of a post hurricane disaster area. In order to provide a controlled environment as well as the attributes that are similar to a hurricane effected area, remote sites must be used. The capstone test and evaluation exercise should occur in a location with limited vehicle mobility, limited power resources, limited network connectivity, and for a duration of at least 7 days. The location will not be resupplied of any system parts, tools, or maintenance parts. This exercise will simulate the conditions that this system may meet when deployed to a disaster site, and the duration would simulate the typical time on the ground this system would remain without support from the rear.

Design Rational

            The major themes used to build the design requirements were durability and self-sufficiency. In regards to durability, the aircraft will need to be shipped, flown, driven, or carried in many different vehicles to reach areas effected by hurricanes. In order to protect the system, while at the same time allowing a single person to transport it, a high level of detail was put on the transportation case. In order to reduce weight and complexity, allowing the transportation case to act not only as a protective case, but also a charging stations and physical location of the GCS helped reduce cost and weight while decreasing additional equipment requirements. The transportation box’s resistance to the elements was vital due to the possibility of the system being stored outside if conditions do not allow for climate controlled indoor storage.

The aspect of self-sustainability is vital due to the fact that after a hurricane, the USPS, UPS, FedEx and other shipping options will often be limited due to destruction of infrastructure such as roads, runways, and ports (Cleary, 2016). The need to have all maintenance parts and tools stored in the transportation case will allow the sole operator of the system to deploy forward into the destruction zone without the need to trek back and forth, which would be both logistically difficult and time consuming. The ability of a single operator to gather multiple claims in a period of week while deployed forward will provide insurance companies with a marked advantage over there competition.

The power and network requirements presented also allow for near real time information flow from the destruction zone to a processing center regardless of power and network availability, which would most likely be either degraded or destroyed following a hurricane. The use of satellite networks, solar power or generators helps not only deploy to areas with limited infrastructure, but also allow for continuous operations without the need to return to the rear.

The entire system was designed to support long term self-contained operations in areas with degraded or destroyed infrastructure. The concept of sending out a small package with a single operator will reduce operational costs as well as logistical costs while maximizing the number of claims an insurance company to collect. The system will also decrease the reaction time that traditional insurance companies need to provide proper insurance claim coverage in hurricane affected areas. 

References

Cleary, T. (2016, October 06). What Is a Category 4 Hurricane? 5 Fast Facts You Need to Know. Retrieved October 25, 2016, from http://heavy.com/news/2016/10/what-is-category-4-hurricane-matthew-damage-strength-history-definition-wind-speed-storm-surge-facts-names/

Sadraey, M. (2010). A Systems Engineering Approach to Unmanned Aerial Vehicle ... Retrieved October 25, 2016, from http://enu.kz/repository/2010/AIAA-2010-9302.pdf 

Unmanned Aerial Systems in National Airspace

     Unmanned aircraft are a vital asset in today’s world. They have made aerial photography and videography cheaper and more accessible to both hobbyists and small business owners.
Today, the major hurtle is UAS integration into national airspace (NAS). One of the major aspects to integration of UAS into NAS is the ability for systems to sense and avoid other aircraft or obstacles. In the current FAA regulations, the term “see and avoid” exist, but in the future “sense and avoid” will be applied (Carey, 2013). Until that point UASs are unable to comply with the requirements, but this has not stopped companies and the military from working towards smart solutions to the providing a sense and avoid system that are dependable enough to garner FAA approval and support.

     The techniques for monitoring separation from both manned and unmanned systems come in multiple forms. The overarching concept, regardless of technique, is that the UAS is informed of nearby traffic and can execute a predictable solution that will provide regulatory separation. The two major techniques to gathering this traffic information can be categorized as ground based or airborne based sensing. Ground based sensing utilize radar systems similar to air traffic control agencies. The major difference is that these radar systems integrate directly into the ground control station (GCS) of the UAS (SRC Inc. 2016). The airborne technique relies on advanced sensors being equipped directly on the air vehicle portion of the UAS. A lot of research is going into the development of micro radar systems that would be able to fit a highly capable radar system into a very small package (Gorwara, 2014).
 
     Some of the major considerations that need to be factored in when deciding between ground based sensing or airborne sensing needs to be attributed to both the size and type of UAS airframe in questions. Small UASs need to be very cognizant of size power and weight of any additional sensors that need to be added to the air vehicle. These systems may benefit from a ground based system that is able to communicate with the ground control station. Additionally, micro radar systems are being produced to provide small quadcopter sized UASs with a robust ability to sense and avoid traffic with light weight and low power solutions (Gorwara, 2014).  Large UASs like military grade UASs have a large payload capacity and a large power source capable of both carrying and powering complex sensors that can provide adequate sense and avoid capabilities. Another aspect to consider is the type of airframe in question. A small quadcopter may move slowly and within a relatively small range. This means less powerful sensors could be used to provide the separation and spacing required. Large fast fixed wing system could fly at high altitudes and at high speeds with an enormous range, so providing powerful onboard solutions may make the most sense.

     Some larger systems like the MQ-4 global hawk actually have terminal collision and avoidance system (TCAS) which is used on most large commercial manned aircraft. There is also research into a new system call Airborne Collision Avoidance System for Unmanned Aircraft or ACAS Xu for short. This system will integrate with TCAS as well as provide autonomous functions that will support proper sense and avoid decision making if the UAS has lost link or is in autonomous flight (NASA, 2015).
 
     Another current initiative is the use of a system called the ground based sense and avoid system (GBSAA) by SRC Inc. This system is currently being installed by the US Army at posts that are hubs for large UAS training. Fort Hood and Fort Campbell are both test beds for this technology (Mishory, 2016). The system utilizes powerful and expensive ground based radar dishes to directly communicate any traffic advisories directly to the GCS of the UASs operating within its area of responsibility. This system can detect both manned and unmanned aircraft as well as other airborne obstacles. The benefits of this system are that just one GBSAA can provide coverage for multiple aircraft working in a defined area. Also, GBSAA does not add any additional power or weight requirements to the actual air vehicles that are utilizing its information (SRC Inc., 2016).

     Regardless to size and type, the need for FAA approved sense and avoid systems is vital to the integration of UAS into NAS. By understanding the limitations and capabilities associated with the size and type of a UAS will help engineers provide the best solution to each system on a case by case basis. The need to ensure the right capability is equipped on the right system is also vital in reducing excess costs and ensuring the general UAS user base is capable and willing to equip their UASs with these systems when it becomes available.  Additionally, integrating the UAS sense and avoid technology into manned sense and avoid systems like TCAS will be vital to future integration.      

 References
Carey, B. (2013, June 22). FAA Plans Unmanned 'Sense and Avoid' Rule in 2016. Retrieved
October 03, 2016, from http://www.ainonline.com/aviation-news/air-transport/2013-07-22/faa-plans-unmanned-sense-and-avoid-rule-2016

Gorwara, A. (2014). Doppler micro sense and avoid radar. Retrieved October 3, 2016, from http://pmi-rf.com/documents/DopplerMicroSenseandAvoidRadarPaper.pdf

Mishory, J. (2016, June 16). Initial UAS flights using GBSAA system at Ft. Hood have been delayed. Retrieved October 03, 2016, from https://insidedefense.com/daily-news/initial-uas-flights-using-gbsaa-system-ft-hood-have-been-delayed

NASA. (2015, January 25). NASA, FAA, Industry Conduct Initial Sense-and-Avoid Test. Retrieved October 03, 2016, from http://www.nasa.gov/centers/armstrong/Features/acas_xu_paves_the_way.html

SRC Inc. (2016). Ground-Based Sense and Avoid Radar System. Retrieved October 03, 2016, from http://www.srcinc.com/what-we-do/radar-and-sensors/gbsaa-radar-system.html

Sense and Avoid Technology for UASs... Risk Mitigation vs. Complete Risk Avoidance

The integration of unmanned aerial systems (UASs) into national airspace (NAS) has been an ongoing process that is slowly but surely making small steps to a future filled with UASs. There are multiple facets that make integrating UASs into NAS a complicated process. Questions that deal with aircraft registration, operator training, ethical responsibility, hacking and lost link procedures are all on the table when it comes to integration into NAS. One topic that has been at the front and center of the integration process is sense and avoid standards and responsibilities for UASs. Companies like Amazon, Google, and Intel are all working solutions to this challenge, but the Military and government entities like NASA are also looking for solutions to getting more robust sense and avoid technology into the skies fast.

Currently in Part 91.113 of the federal aviation regulation, it lays out the rules of the sky in terms of right of way for all aircraft. One key verbiage used is that aircraft must “see and avoid”. This does not include the ability to sense and avoid, which is the method by which a UAS would accomplish this same task. Due to this, these regulations are very limiting to UAS operation. For military UAS this means that we must have visual observers that are trained and qualified observing the aircraft at all times while operating in NAS. This creates a huge logistical addition to typical training missions and is a cumbersome task to accomplish when it comes to personnel and crew management. It is reported that the FAA is attempting to alter Part 91.113 this year in order to include sense and avoid technology as a legal substitute for see and avoid (Carey, 2013).

The Army specifically has been working with a ground based sense and avoid system (GBSAA) to augment their ability to fly in NAS. I have worked with this technology during my time as a UAS commander in the Army and have seen how beneficial proper implementation could be for units stationed in the US. GBSAA works very similarly to ground based ATC radar systems, the only difference is that it is completely dedicated to a particular UAS mission. The radar picture of both participating and non-participating aircraft is collected via LSTAR ground sensors and overlaid on the ground control station’s display and moving map that is utilized by the operator to navigate the UAS (SRC Inc., 2016). When fully functional and approved by the FAA, this system would allow the Army to fly large UASs through Military Operations Airspace (MOA). For locations like Fort Campbell, Kentucky, this would greatly expand the operational area for the multiple UAS units stationed there. 

Depiction of Ground Based Sense and Avoid System by SRC Inc. 

In the civilian sector, there is a greater focus on autonomous sense and avoid capabilities. This technology will allow for smaller UASs to go further and farther than ever before. For companies like Amazon, who want to be able to deliver merchandise via UAS, it will be imperative that they can utilize autonomous drones that will legally be authorized to travel beyond line of sight as long as they are equipped with autonomous sense and avoid technology (Popper, 2016).

Regulators are attempting to find a perfect answer to the sense and avoid issue, but the technology is currently very good, but not perfect. Some argue that the technology needs to be better, while others argue that aviation has always been about risk mitigation and not risk avoidance. Companies like Intel have produced sense and avoid systems that could reduce risk nearly to zero, but not promise a perfect solution to every scenario (Popper, 2016). Many feel that the same risk acceptance levels applied to manned aviation should be carried over to unmanned aviation rather than attempting to create a more stringent and difficult standard to achieve. What do you think is the best way forward? Please feel free to respond in the comments section below.    

References:

Carey, B. (2013, July 22). FAA Plans Unmanned 'Sense and Avoid' Rule in 2016. Retrieved August 17, 2016, from http://www.ainonline.com/aviation-news/air-transport/2013-07-22/faa-plans-unmanned-sense-and-avoid-rule-2016

FAA. (2004). Part 91 GENERAL OPERATING AND FLIGHT RULE. Retrieved August 17, 2016, from http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/934f0a02e17e7de086256eeb005192fc!OpenDocument

Popper, B. (2016, January 16). What's really standing in the way of drone delivery? Retrieved August 17, 2016, from http://www.theverge.com/2016/1/16/10777144/delivery-drones-regulations-safety-faa-autonomous-flight

SRC Inc. (2016). Ground-Based Sense and Avoid Radar System. Retrieved August 17, 2016, from http://www.srcinc.com/what-we-do/radar-and-sensors/gbsaa-radar-system.html

What Kind of Unmanned System Will Make the Greatest Impact on Society in the Future?

I feel that future development of unmanned aerial systems (UASs) will have the greatest impact to society compared to the future impacts of unmanned marine and ground systems. The reason why I feel this way is based on three key industries that will be greatly affected by UAS development; agriculture, transportation, and defense.  These three industries account for the most important sectors of the economy according to the US Department of commerce. Agriculture is number one for the United States, but also plays an absolutely essential role in lesser developed counties as well. Transportation is essential because it links all over services and industries to the end user, and defense is important because ultimately, when politics fail, it’s the county with the best military remains in power. Marine and ground based unmanned systems will continue to develop and shape these sectors, but opening the aerial layer to industry will provide previously unobtainable perspective, convenience, and progress.

Agriculture: There are two major aspects to agriculture that will be affected by the development of UASs; precision agriculture, and crop dusting and treatment. Precision agriculture is a farming technique that uses high tech overhead imagery to observe, measure, and respond to inter and intra field variability. In the past this could only be done via satellite or manned aircraft which resulted in costs that were too high for the average farmer to afford. Today, with the introduction of UASs, every farmer, no matter how big or small, is gaining access to this ability. The use of unmanned crop dusting and crop treatment is complimented by precision agriculture. The ability to link both precision agriculture and unmanned crop treatment means a small farmer could optimize their land to provide the highest and most cost effective crop yield scientifically possible. If applied over a large enough population, this technology could change global food yield and resources for the better.

Transportation: The transportation sector is the link between industry and the end users. The transportation sector touches almost every other sector of the global economy in some way. As globalization continues, the importance of effective and fast transposition of people and goods is becoming more important every day. The ability to fly long distance global missions can be accomplished cheaper and more efficient with large scale UASs. In terms of local and hyperlocal transportation, the use of small quadcopter may become the standard method of local delivery. Amazon has been working with the FAA to start a new program in which deliveries could be made by quadcopters within a local area. This could be a start to a future of bustling UAS highways in the air. Not only could it reduce traffic, emissions, and delivery times, but it could launch counties without proper road networks into the 21^st century for minimal costs.

Defense: Currently, only a few countries rely on military UASs as heavily as the United States. It is clear that the introduction of the UAS has redefined the battlefield, but the one aspect of this technology that will effect society in the future is its availability. As UAS technology becomes cheaper and more accessible it will be spread to all international powers regardless of state affiliation, size, or political standing. In the future we could see separatist states, terrorists, or major adversaries gain access to extremely dangerous weapons and use them to disrupt peace and stability globally.  

References:

Becker, S. (2014, July 1). What Are the Most Important Sectors in the U.S. Economy? Retrieved May 20, 2015, from http://www.cheatsheet.com/business/what-are-the-most-important-sectors-in-the-u-s-economy.html/?a=viewall

Gopal, S. (2015, February 20). Drones: The Game Changers in Future Wars. Retrieved May 20, 2015, from http://www.indiandefencereview.com/news/drones-the-game-changers-in-future-wars/

Grassi, M. (2015, May 7). FAA Enters Partnerships To Consider Beyond Line-Of-Sight UAV Missions | PrecisionAg. Retrieved May 20, 2015, from http://www.precisionag.com/data/imagery/faa-enters-partnerships-to-consider-beyond-line-of-sight-uav-missions/

Jones- Cruise, C. (2015, March 18). Amazon Receives Patent for Drone Delivery System. Retrieved May 20, 2015, from http://learningenglish.voanews.com/content/amazon-receives-patent-for-drone-delivery-system/2776033.html