ASCI 638, Module 4: UAS Beyond Line of Sight Operations

The Aerosonde family of aircraft began development in 1991 in response to a growing need for accurate oceanic weather data and the great expense of using ships and manned aircraft to launch weather sondes. The implementation of small GPS units and robotic controllers led to the development of the Aerosonde system, which could conduct a flight and conduct data collection over a very large area for the same cost as a weather sounding balloon (McGeer, 1999). The aircraft first flew in 1995, and work began to plan a trans-Atlantic flight. Aerosonde Laima successfully crossed the Atlantic Ocean from Bell Island, Newfoundland to South Uist, Scotland in August 1998, burning less than 2 gallons of fuel in a 26 hour 45-minute flight.

Figure 1. Aerosonde Laima flight track, 20-21 August 1998.

          The Aerosonde uses the CloudCap Piccolo family of flight controllers. The Piccolo ground station is based on the same hardware as the airborne autopilot and provides the datalink to the aircraft, a pilot-in-the-loop interface for line of sight operations, and an interface for command and control via a PC (Vaglienti, Hoag, and Niculescu, 2005). Because the Piccolo is purpose-built for beyond-line-of-sight (BLOS) operations, a minimum crew of three was used for the 1998 flight and following operations: the pilot operating the command and control interface, an External Pilot (EP) for visual line of sight (VLOS) operation during launch and landing phases, and a ground crewmember to operate the launch and recovery system. The 1998 flight utilized a car-top launcher, while later versions of the system use a hydraulic catapult launch and net recovery system (McGeer, 1999 and AAI Corporation, 2016). Ground support equipment for crew communication systems is required, as the pilot does not typically have visual line of sight to the aircraft throughout the operation. Coordination of the launch is performed by the ground crewmember and the EP, with the pilot providing a backup role in relaying telemetry data to the EP, such as airspeed and altitude. The EP only has control of 5 channels: one each for pitch, roll, yaw, throttle, and mode switching; the pilot has control of autopilot commands and engine ignition. Following a successful launch, the EP will turn over control to the autopilot, which will follow waypoints and flight modes as input by the pilot. The autopilot will also automatically take over flight control if input from the EP is interrupted (Vaglienti, Hoag, and Niculescu, 2005).

The advantage of using a BLOS system such as the Aerosonde/Piccolo is that a much greater area can be surveyed than remaining within VLOS. An example is the long-range weather data collection test flights that were conducted by the Aerosonde system in 1999. Flights were launched from Atlantic Field near Cherry Point, NC and flown to Pamlico Sound, about 20 miles North. The flights were controlled form Norfolk Naval Station in Virginia, about 100 miles away (Holland et. al, 1999). Follow-on flights were conducted over the Atlantic Ocean and in the Arctic/Antarctic research areas. More recently, an Aerosonde was used in March 2017 to conduct BLOS power transmission lines in New Zealand (Groenestein, 2017).

The disadvantage of BLOS operations is the dependence on the datalink. The Laima crew originally intended to fly to Ireland, but were denied entry into Irish airspace because of a rule requiring trans-Atlantic aircraft to provide position reports every hour when operating within controlled airspace, something the Aerosonde crews could not reliably provide, as their datalink was limited to radio line of sight; the Laima was flying an automated flight path (McGeer, 1999). Situation awareness is also compromised by the inability to see or feel the aircraft environment; all sensory input is provided through visual interpretation of the ground station control software. A large amount of human factors research in UAS centers on this issue.

Figure 2. Aerosonde with UTC Aerospace TASE daylight camera view of forest fire.

Commercial applications of BLOS flight include long-range infrastructure inspection (as in New Zealand) and intelligence, surveillance and reconnaissance (ISR) collection for military customers. An additional potential commercial mission that has been tested by the Aerosonde is in wildland fire fighting. In 2015, a team from AAI Corporation used an Aerosonde to fly over the Teepee Spring Fire in Idaho, providing real-time imagery during the night – a period when manned firefighting aircraft are grounded for safety. Active surveillance during the night provides incident commanders on the ground with information to make decisions to place assets when daylight is available (Ridler, 2015).

References

AAI Corporation. (2016). Aerosonde SUAS. [Brochure]. Retrieved from http://www.textronsystems.com/sites/default/files/resource-files/TS%20US%20Aerosonde%20Datasheet.pdf

Groenestein, C. (2017, March). Taranaki company makes history with drone flight. Taranki Daily News. Retrieved from http://www.stuff.co.nz/taranaki-daily-news/news/90012497/taranaki-company-makes-history-with-drone-flight

Holland, G. J., Webster, P. J., Curry, J. A., Tyrell, G., Gauntlett, D., Brett, G., … & Vaglienti, W. (2001). The Aerosonde robotic aircraft: A new paradigm for environmental observations. Bulletin of the American Meteorological Society, 82(5), 889-901.

McGeer, T. (1999, February). Laima: the first Atlantic crossing by unmanned aircraft. Retrieved from http://aerovelco.com/wp-content/uploads/2015/03/Laima_the-first-Atlantic-crossing-by-unmanned-aircraft1.pdf

Ridler, K. (2015, September). Wildfire managers plan drone test over Idaho blaze. The Gazette. Retrieved from http://gazette.com/wildfire-managers-plan-drone-test-over-idaho-blaze/article/feed/272561

Vaglienti, B., Hoag, R., and Niculescu, M. (2005, April). Piccolo user’s guide version 1.3.0. CloudCap Technology: Hood River, OR.