NMSU?New Mexico State University’s Physical Science Laboratory partnered with AeroVironment to study the safety of small, unmanned aircraft system operations at night in the National Airspace System. Study results strongly indicate nighttime operations of unmanned aircraft systems are safe, maybe even more so than daytime operations.
“We initially proposed to conduct live-fly demonstrations at night and twilight to assess the ability of the pilot-in-command and visual observer of a small UAS to acquire the UAS, other tracks or targets and make a determination as to potential collisions,” said Doug Davis, project principal investigator and director of the Physical Science Laboratory’s Global UAS Strategic Initiatives.
Igor Dolgov, assistant professor in the NMSU Department of Psychology and project lead experimenter, designed the study for NASA comparing the performance of unmanned aircraft observers, those who visually track the aircraft during flight, during daytime operations vs. nighttime operations.
Dolgov executed the study and conducted data analysis in partnership with AeroVironment and the Physical Science Laboratory team consisting of mission commanders Doug Marshall and Brendan Shaughnessy and ground control coordinators Luis Salas and Daniel Mendoza.
AeroVironment personnel flew the company’s Raven and Wasp small unmanned aircraft systems for the study.
“I’m an engineering psychologist and my specialty is sensation and perception,” Dolgov said.
“In terms of evaluating the safety of UAS night flights, it’s a matter of determining whether the observers’ task of detecting intruder aircraft into the UAS’s operational space at night is as safe as during the day, and whether or not they can accurately provide the UAS pilot with instructions to perform an avoidance maneuver, if necessary.”
Some of the observations studied include whether or not unmanned aircraft observers were able to accurately estimate the time to contact between the UAS and intruding aircraft in the process of informing the UAS pilot to perform an avoidance maneuver. Traditional measures such as visual acquisition distance and proportion of time that the craft were visible were also collected.
Data analysis of both phases of the study are complete, confirming that observers were able to visually acquire incoming aircraft at night and advise timely avoidance maneuvers, if necessary.
“Aircraft are frequently more visible at night because of their lighting systems; moreover, observers are able to use night vision goggles to assist them in spotting intruding aircraft,” Dolgov said. “In fact, whenever statistically significant differences in observers’ judgments were identified in the study, the data favored night operations over day across the board.”
In phase two, acquisition of intruding manned aircraft at night occurred nearly a kilometer farther away than during the day. A similar trend in night observation superiority was seen in the Raven and Wasp data, but the differences were not statistically significant.
The findings demonstrate the importance of the observer being co-located with the small unmanned aircraft pilot, evidenced by the superior tracking ability and superior sensitivity when co-located compared to when they were remotely situated and communicated via radios.
The study also found that while there is little likelihood that the pilot of a manned aircraft would see a small unmanned aircraft during the day, it is not out of the question at night, particularly if lighting systems were designed specifically for this type of identification. Observers identified aircraft with adequate time to relay its position and trajectory to the small, unmanned aircraft pilot, regardless of time of day, in order to avoid collision.
The safety case for night operations is impacted by the fact that there is less air traffic at night, especially in the airspace of 1,000 feet and below, where the small unmanned aircraft systems this study examined could be operated by agencies such as the Department of Homeland Security and law enforcement in the future.
More testing to come
Research was conducted at East Mesa and the Jornada Experimental Range.
“NMSU is one of the only places outside of military facilities where you can conduct this kind of testing right now,” Dolgov said.
Because of the remoteness of the area, the Physical Science Laboratory team hopes to conduct an additional year of research to simulate light and sound pollution that is typical of urban environments.
“We will propose to continue the demonstrations by stressing the light pollution environment on the pilot in command and the visual observer so we can supply much needed data to the Department of Justice, as well as NASA and the Federal Aviation Administration about conducting night operations with small unmanned aircraft systems, especially for law enforcement and first responders in urban areas,” said Davis.
“There are currently significant restrictions on UAS night flights, which prevents a lot of agencies from utilizing them when they really need them,” Dolgov said. “The goal of this study is to come up with a safety case, or set of parameters that would allow for safe UAS operation at night, which would open it up to law enforcement, homeland security, commercial and research applications.”
The Physical Science Laboratory released findings of the night flight study report to NASA, who in turn released it to the FAA. The report concludes that while additional testing should be conducted to confirm these results in alternate contexts and to investigate additional aspects of small, unmanned aircraft system night operations, the current studies suggest that the current limits placed on night small, unmanned aircraft system flights are overly conservative.