NASA flight tests help finalize detect-and-avoid standards

By the end of the year, General Atomics Aeronautical Systems Inc. government customers flying the MQ-9 Predator should be another step closer to operating in U.S. and international airspace.  

A fourth and final round of flight tests that began in late April and will conclude at the end of June are being conducted at the NASA Armstrong Flight Research Center in California. NASA is partnering with General Atomics, the Federal Aviation Administration (FAA), Honeywell International and the Radio Technical Commission for Aeronautics (RTCA) Special Committee 228 to assist with the integration of unmanned aircraft systems (UAS) in to the national airspace system.

“After this flight test, NASA theoretically has detect-and-avoid capabilities they can get approved by the FAA,” said Brandon Suarez, General Atomics project engineer. “And we think that if NASA can get approval to fly with this system, then other customers of the MQ-9 Predator B product line could get similar approval with the same system.”

The flight tests involve 270 high-speed and low-speed encounters between manned and unmanned aircraft to help verify and validate minimal operational performance standards for UAS being developed by RTCA SC-228. NASA’s Ikhana UAS—a civilian research version of General Atomics’ Predator B—is equipped with a detect-and-avoid (DAA) system.

Manned aircraft—called intruders—are flying encounters with the Ikhana. The intruders include NASA’s B200 King Air, T-34C, Gulfstream III, TG-14, Honeywell’s C-90 King Air and the U. S. Air Force's C-12 King Air. The goal is to test the DAA system under a wide variety of conditions against aircraft flying at different speeds, altitudes and geometries.

“Our engineers have generated a very detailed and complex flight test plan that integrates all of the variables needed to execute this flight test,” said Heather Maliska, UAS-NAS deputy project manager at Armstrong.

Suarez said SC-228 members had a high level of participation in designing the flight tests and will be analyzing the data gathered from the tests.

“That’s been very important in that we have the committee providing oversight and actual involvement in the test planning process,” he said. “We’ll have data analysis coming from NASA, from General Atomics, from Honeywell and members of SC 228; it’s really a collaborative effort.”

In addition, SC-228 has led a modeling and simulation effort conducted by the Air Force, NASA and the FAA to run millions of test points required to prove that the system works in all conceivable operational scenarios.

“The flight test is there to validate the simulations and prove that, practically speaking, we can build a system that meets the requirements,” Suarez explained. “We can compare the simulation results to the test results and make sure the simulation is representative of what we see in the real world.

“That’s important both from a sensor perspective as well as an overall system performance perspective to make sure that what the pilot sees in the real world actually matches what we expect him to see,” he added.

According to Suarez, NASA will be conducting a human-in-the-loop experiment this month. In July, RTCA SC-228 will meet to discuss the results from the flight tests and the experiment. The plan is to put the finishing touches on the minimum operational performance standards by September and have them approved by December.

“If everything goes according to plan, we will have the technical standard published before the end of the calendar year,” Suarez said.

From General Atomics’ perspective, this will help the company expand its pilot training programs in the national airspace, he said.

“It should enable our government customers to have more operational flexibility in the NAS and not have to use chase planes as frequently as they do,” Suarez continued. “We would still be operating under our COA—as would our government customers—but the operational restrictions in those COAs could be lightened substantially.”

Suarez said work has begun on Phase II of the program in which General Atomics is working with the FAA, Honeywell and ACSS to develop ACAS-XU, a collision avoidance system for unmanned aircraft. He expects the Predator B to fly with functional detect-and-avoid capabilities before the end of the year.

“The primary goal of the Phase II effort is to enable extended operations in all classes of airspace,” Suarez said. “That’s really the key step to getting full file-and-fly access.”

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