BLOS Capability Enables the RQ-4 Global Hawk to Live Up to Its Name

BLOS Capability Enables the RQ-4 Global Hawk to Live Up to Its Name

Daniel J. Hall, Jr.

ASCI 638 – Human Factors in Unmanned Systems

Embry-Riddle Aeronautical University-Worldwide

June 28, 2014

BLOS Capability Enables the RQ-4 Global Hawk to Live Up to Its Name

The ability to command and control (C2) unmanned aerospace systems (UAS) beyond the line of sight (BLOS) of the operator has greatly expanded the utility of these systems.  BLOS capability has been enabled through the advancement of satellite communications (SatCom), global positioning system (GPS) technology, and long range data links.  One UAS that utilizes BLOS C2 to truly live up to its name is the Northrop Grumman Global Hawk.

The Northrop Grumman Global Hawk has been in development since “1995” (Northrop Grumman Corporation, 2008, p. 2).  With its ability to fly for more than 24 hours at altitudes above 50,000 feet mean sea level (Northrop Grumman Corporation, 2008), Global Hawk operators have used its BLOS capability to set records in long range operations.  According to Northrop Grumman Corporation (2008), “Global Hawk flew 7,500 miles nonstop across the Pacific to Australia on April 22-23, 2001, setting several new world records for UAS endurance” (p 2).

There are several methods available for conduction BLOS operations with UAS.  The employment of ground or air based radio frequency (RF) repeaters is one method to facilitate BLOS operations.  Another method is to capitalize on the ability to skip RF signals off of the atmosphere.  However, according to Avionics Today (2013) the primary method for conducting UAS BLOS operations is via “satellite communications” (para. 4).  Avionics Today (2013) details the use of the Inmarsat satellite communication system to enable BLOS operations:

There’s been new advancements on the SatCom side, particularly with Inmarsat and SwiftBroadband.  These new advances in service and terminals are changing the landscape dramatically.  Inmarsat’s new SwiftBroadband and I-4 satellites have ushered in an era of new smaller, lighter, less expensive terminals that can bring a beyond-line-of-sight data link capability to more UAV types and to more applications. (Avionics Today, 2013, para. 5)

The Global Hawk utilizes several links for satellite communications.  According to Northrop Grumman Corporation (2008), the Global Hawk communication package includes “Ku SatCom Data link, CDL LOS, UHF SatCom/LOS, Inmarsat, ATC Voice, Secure Voice” (p 5).  Specifically, the Ku SatCom Data link, UHF SatCom, and Inmarsat communications links are the components that provide the Global Hawk with its redundant BLOS capabilities.  Satellite communication links are provided for the Global Hawk via several antennas however, the Global Hawk’s distinctive hump just aft of the nose houses a large satellite dish for the primary Ku SatCom data link (Northrop Grumman Corporation, n.d.).

Research and development with BLOS technology offers the potential of greater reliability and flexibility for the UAS community.  Avionics Today (2013) stated, “When they have the capacity for an over-the-horizon type view, it gives them even more of an application across all platforms” (para. 3).  For example, Northrop Grumman recently demonstrated a “unique split link capability for Global Hawk that allows it to send mission data through a satellite link that is independent of the link used for command and control” (Northrop Grumman Corporation, 2014, para. 2).  However, in the author’s opinion, the high cost and restricted access of satellite communications may limit the commercial application of BLOS UAS capabilities for the foreseeable future.

References

Avionics Today. (2013, March 1). UAV communications. Retrieved from http://www.aviationtoday.com/av/issue/feature/UAV-Communications_78540.html#.U7AaLSDD9Ms

Northrop Grumman Corporation. (2008, May). Facts: RQ-4 Global Hawk high-altitude, long-endurance unmanned aerial reconnaissance system. Retrieved from http://www.northropgrumman.com/Capabilities/RQ4Block20GlobalHawk/Documents/HALE_Factsheet.pdf

Northrop Grumman Corporation. (2014, April 3). Global Hawk expands satellite communications capability. Retrieved from http://www.globenewswire.com/newsarchive/noc/press/xml/nitf.html?d=10075411

Northrop Grumman Corporation. (n.d.). Northrop Grumman RQ-4 Block 40 Global Hawk cutaway diagram. Retrieved from http://www.northropgrumman.com/Capabilities/GlobalHawk/Documents/Cutaway_Drawing_GH_Block_40.pdf

UAS Integration in the NAS

While the current state of sense and avoid (SAA) technology in unmanned aerospace systems (UAS) is still in the research and development stage; efforts by the Federal Aviation Administration (FAA) to safely integrate UAS into the National Airspace System (NAS) are underway.  One such effort is the Next Generation Air Transportation System (NextGen) initiative.  “NextGen represents an evolution from a ground-based system of air traffic control to a satellite-based system of air traffic management.  This evolution is vital to meeting future demand, and to avoiding gridlock in the sky and at our nation's airports” (Federal Aviation Administration, 2013a, para. 1).

 

The requirement for UAS to be capable of sensing and avoiding other aircraft while operating in the NAS is mandated in the FAA Modernization and Reform Act of 2012.  The FAA Modernization and Reform Act of 2012 requires Federal agencies to “ensure that any civil unmanned aircraft system includes a sense and avoid capability” (Title III, Subtitle B, Sec. 332).  This act also calls upon Federal agencies to safely integrate UAS into the NAS as soon as possible but “not later than September 30, 2015” (FAA Modernization and Reform Act of 2012, Title III, Subtitle B, Sec. 332).  With the enactment of the FAA Modernization and Reform Act of 2012 on February 14, 2012 the Federal Aviation Administration began the process of integrating UAS into the NAS.

 

A key component of the NextGen initiative that could facilitate the employment of SAA technology is the development and implementation of the satellite-based Automatic Dependent Surveillance-Broadcast (ADS-B) system.  “ADS-B makes use of GPS technology to determine and share precise aircraft location information, and streams additional flight information to the cockpits of properly equipped aircraft” (Federal Aviation Administration, 2013a, para. 1).  ADS-B technology combined with future developments in SAA systems could be the key to unlocking the commercialization of UAS in the NAS.

 

Mid-air collision avoidance in today’s NAS is achieved through a variety of means such as ground based radar monitoring by air traffic control personnel, pre-established airport approach and departure procedures, specified air traffic routes and altitudes, Traffic Alert and Collision Avoidance Systems (TCAS) onboard the aircraft, and the pilot’s visual scan of the airspace around the aircraft (Eshel, 2013b; Federal Aviation Administration, 2013b; Munoz, Narkawicz, & Chamberlain, n.d.).  “Unmanned flight will require new or revised operational rules to regulate the use of SAA systems as an alternate method to comply with ‘see and avoid’ operational rules currently required of manned aircraft” (Federal Aviation Administration, 2013b, p. 19).  According to the Federal Aviation Administration (2011), “efforts are underway to define System Requirements and Minimum Performance Standards for Sense and Avoid (SAA) equipment for UAS [however,] these efforts are in their early stages of requirements definition with completion schedule estimates beyond 2015” (p. 5).

 

The author believes that the full implementation of NextGen will be the key to unlocking the NAS for commercial UAS operations.  However, the author disagrees with the requirement that all UAS be equipped with SAA capability prior to operating in the NAS.  The main reason is that SAA technology is a long way from being operational on any UAS platform large enough to carry it let alone the overwhelming majority of smaller UAS platforms that will need miniaturized versions of the onboard SAA equipment.  The author suggests that the FAA develop rules and procedures that permit the use of UAS without SAA capability at altitudes below 1,000 feet above ground level (AGL) while amending the rules to require all manned aircraft to operate at 1,100 feet AGL and above.  Obviously, certain exceptions to this altitude restriction could be granted for manned aviation operations such as crop dusting.  This would provide vertical separation of small UAS operating at 1,000 feet AGL and below and manned aircraft operating at 1,100 feet AGL and above.  Adopting rules and procedures like this would then require larger UAS intended to operate higher than 1,000 feet AGL to be equipped with SAA capabilities in order to avoid manned aircraft.

 

References

Eshel, T. (2013b, June 27). Airborne sense and avoid radars for RPAs. Defense Update. Retrieved from http://defense-update.com/20130627_absaa_sense-and-avoid-for-rpa.html

FAA Modernization and Reform Act of 2012, Pub. L. No. 112-95, (2012). Retrieved from http://www.faa.gov/about/office_org/headquarters_offices/apl/aatf/legislative_history/media/faa_modernization_reform_act_2012_plaw-112publ95.pdf

Federal Aviation Administration. (2011, March 21). Evaluation of candidate functions for traffic alert and collision avoidance system II (TCAS II) on unmanned aircraft system (uas). Retrieved from http://www.faa.gov/about/initiatives/uas/media/TCASonUAS_FinalReport.pdf

Federal Aviation Administration. (2013a, May 13). What is NextGen? Retrieved from http://www.faa.gov/nextgen/why_nextgen_matters/what/

Federal Aviation Administration. (2013b, November 7). Integration of civil unmanned aircraft systems (UAS) in the National Airspace System (NAS) roadmap (1st ed.). U.S. Department of Transportation. Retrieved from http://www.faa.gov/about/initiatives/uas/media/UAS_Roadmap_2013.pdf

Munoz, C., Narkawicz, A., & Chamberlain, J. (n.d.). A TCAS-II resolution advisory detection algorithm. Retrieved from http://shemesh.larc.nasa.gov/people/cam/publications/gnc2013-draft.pdf

Human Factors in the Triton Ground Control Station

Human Factors in the Triton Ground Control Station

Ground control stations (GCS) for unmanned aerospace systems (UAS) take many forms depending upon the size and complexity of the system.  Austin (2010) wrote, “control stations, like the aircraft, come in all shapes and sizes and are staffed appropriately to the number and specialty of the tasks which they are required to perform” (p. 185).  GCS can range from simple hand held devices, to a single laptop computer, to mobile systems of networked computers and monitors, to fixed based stations with satellite links and a team of operators.

Ground control stations are used to send command and control (C2) information to the UAS.  GCS may also be used to direct the operation of UAS payloads and sensors when applicable.  Austin (2010) described the GCS as the “man-machine interface with the unmanned air vehicle (or air vehicles) system” (p. 183).  The GCS may also be used to receive information such as vehicle telemetry status and sensor images or data from the UAS via down-links (Austin, 2010).  Another factor that determines the complexity of the GCS is the operational distance between the GCS and the UAS.  UAS operated within line of sight (LOS) of the operator are much less complex than GCS used for UAS operations beyond the line of sight (BLOS) of the operator.

The most complex level of GCS are required for UAS that are designed for high altitude, long endurance (HALE) missions BLOS of the operator (Austin, 2010).  “Systems such as Predator and Global Hawk may launch their aircraft from a GCS on airfields relatively close to the theatre of operation but, after launch, be controlled from a command center which may be up to two thousand kilometers away” (Austin, 2010, p. 193).  This type of GCS requires two way, satellite linked, BLOS capabilities for transmission of C2, telemetry, and payload data.  To picture this type of GCS picture the TV images that show the inside of a NASA control room.

According to Naval-technology.com (n.d.), the Triton UAS “is operated from ground stations manned by four-man crew including an air vehicle operator, a mission commander and two sensor operators” (Ground Control Station).  In addition to the flight crew outlined above, complex UASs such as the Triton may be monitored by a crew of engineers specializing in various subsystems of the air vehicle.  This crew of engineers could dramatically increase the total number of humans either directly involved in controlling the UAS or providing decision-making input.  Since the Triton UAS “can fly 24 hours a day, seven days a week with 80% effective time on station (ETOS)" (Naval-technology.com, n.d., Ground Control Station); there is a high potential for human factors to negatively impact the flight operation.

Two negative human factors that may arise when so many people have access to the Triton GCS over such an extended flight duration are complacency and miscommunication.  Complacency can creep into the flight operation when one member of the team incorrectly assumes that another member is monitoring a system or flight parameter and will take corrective action if necessary should an anomaly arise.  Miscommunications may be experienced between members of the team when non-standard terminology is used or when checklists and Standard Operating Procedures (SOPs) are not adhered to.  In both cases, complacency and miscommunication, the most effective way to mitigate risk is to enforce the use of prescribed terminology and adherence to checklists and SOPs.

References

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

Naval-technology.com. (n.d.). MQ-4C Triton Broad Area Maritime Surveillance (BAMS) UAS, United States of America. Retrieved from http://www.naval-technology.com/projects/mq-4c-triton-bams-uas-us/