"That's when you put in values anywhere that a human could put in a number, like minus one feet, or a million feet, to see what that would do," said Jeff Moss, founder of the Black Hat and Def Con security conferences and an advisor to the Department of Homeland Security.
While it might be logical to limit the amount of data associated with one flight plan, anything exceeding that amount should not be able to render the system useless, they said.
Though they welcomed the FAA's assurance that a fix was being rolled out, they said the incident suggested that similar failures could be found.
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"If it's now understood that there are flight plans that cause the automated system to fail, then the flight plan is an 'attack surface,'" said Dan Kaminsky, co-founder of the White Ops security firm and an expert in attacks based on over-filling areas of computer memory.
"It's certainly possible that there are other forms of flight plans that could cause similar or even worse effects," Kaminsky said. "This is part of the downside of automation."
Moss said many hackers have been studying aspects of a new $40 billion air traffic control system, known as NextGen, which encompasses ERAM, including its reliance on Global Positioning System data that could be faked.
At least two talks at this summer's Def Con will look at potential weaknesses in the system.
"It's very over-budget and behind schedule, so it doesn't surprise me that it's got some bugs - it's the way it presented itself" that's alarming, Moss said.
But air traffic controllers and pilots said ERAM is a vast improvement over past systems and that it is needed to fit growing plane traffic into the airspace safely.
Nate Pair, president of the Los Angeles Center for the National Air Traffic Controllers Association, said it was remarkable that ERAM was restored less than an hour after the outage, limiting the effect on travelers.
"We were completely shut down and 46 minutes later we were back up and running," Pair said.
"That could have easily been several hours and then we would have been into flight delays for days because of the ripple effects."