Air traffic controllers in Denver lost communications for 90 seconds with an estimated 20 planes operating in the airspace surrounding Denver International Airport on Monday, forcing them to scramble to use backup frequencies in the latest incident of Federal Aviation Administration equipment failure.

The outage at DIA affected communications, not radar, said the FAA’s head of air traffic control, Frank McIntosh, during a House hearing on Thursday. The communications failure followed two high-profile outages of radar and communications in the past few weeks at a facility that directs planes in and out of the Newark, New Jersey airport.

While FAA officials said controllers in Denver were able to use an alternate frequency to contact pilots, the incident added to mounting worries surrounding aviation safety in the United States.

Experts said the country’s historical lack of prioritization of its national airspace has left it lagging behind other developed countries, such as Norway and Germany.

Earlier this month, U.S. Department of Transportation Secretary Sean P. Duffy unveiled a plan to build a “brand new, state-of-the-art air traffic control system that will be the envy of the world.”

“Under President Trump, America is building again. Today, we are seizing a once-in-a-generation opportunity to build a brand new, state-of-the-art air traffic control system,” Duffy said in a statement. “Decades of neglect have left us with an outdated system that is showing its age. Building this new system is an economic and national security necessity, and the time to fix it is now.”

But it could be years before the nation completes such a plan, if it is even approved.

More controllers needed

Meanwhile, as demand for commercial air travel grows, short-handed air traffic controllers are struggling to keep up.

The FAA has about 14,000 air traffic controllers. More than 1,800 were hired last year, the most significant number in nearly a decade, and the government is on track to hire even more this year. Still, about 3,000 more are needed to fully staff the system.

Metropolitan State University air traffic control instructor Tom Obarski, a former air traffic controller, estimated that the student washout rate from the FAA’s Oklahoma City ATC training academy is around two-thirds.

“And then people also wash out in the field,” said Obarski.

FAA officials said they have streamlined the hiring process through targeted automation and process improvements, which will accelerate the time-to-hire for these critical positions by five months or more, bringing new air traffic controllers on the job much faster.

“We are on track to hire another 2,000 controller trainees this year,” FAA officials said. “We are reviewing our hiring, training, and placement processes, as well as FAA Academy withdrawals and failures, to ensure our selection methods effectively identify candidates best suited for the controller profession.”

Unnerving, but not unmanageable

Although any loss of communications between aircraft and the tower is cause for concern, pilots are taught and tested on this throughout their careers, beginning at the student pilot level.

“Actually, it’s covered in two of our certifications,” commercial flight instructor and FAA Designated Flight Examiner Nelson Wolfmeier told The Denver Gazette. “We get tested on two-way radio communication failure at the instrument level, and then we get tested again when we hit our air transport pilot (ATP) rating later on down the road.”

Standardized training and procedures among both pilots and controllers provide a certain level of comfort during such incidents, according to Wolfmeier.

On top of that, most modern commercial aircraft have multiple redundant radios and other ways to relay information.

“What I like to do with flight training is think outside the box,” Wolfmeier said. “How else can we get hold of people? You know, we got Wi-Fi, and a lot of airliners now could drop an email to the Denver Center. The big thing is, with the big airliners, they’re going to radio back to their dispatch.”

Wolfmeier said in some cases, pilots simply use a cell phone to call the tower directly in the event of a communications loss.

Is future of air traffic control automated?

The Trump administration plans to revamp the nation’s air traffic control system to address critical safety needs. The FAA said the plan will replace core infrastructure, including radar, software, hardware and telecommunications networks to manage modern travel.

In the meantime, some experts say AI could help the nation’s aging air traffic control system, as well as augment human decision-making and reduce the cognitive demand on controllers.

In fact, it’s already helping train future air traffic controllers and pilots at MSU Denver’s World Indoor Airport.

MSU Denver’s air traffic control program is part of the FAA’s Collegiate Training Initiative, designed to provide a foundation for students interested in becoming air traffic control specialists. MSU Denver is one of only 36 higher education institutions across the country designated by the FAA as part of its Collegiate Training Initiative and is an FAA-approved AT-CTI program. Weather, airspace, teamwork in aviation, navigation, and search and rescue are among the fundamentals covered in this course.

The program currently has about 100 students enrolled from both the air traffic control program and the professional pilot program.

In a small, nondescript classroom in downtown Denver, multiple computer screens and an AI-based training system put future air traffic controllers — and pilots — through the paces, sharpening their situation awareness and radio communications skills.

Luke Nugent, a senior in the professional pilot program who verbally instructs multiple simulated aircraft inbound to his computerized air traffic control “tower,” said the air traffic control program has helped him become a better pilot.

“You get to learn the other side,” Nugent said. “You get to learn who’s in the tower talking to you, and it just gives you that extra edge, that you’ve had the training as well, so you know what they (controllers) are thinking, as well as what you’re going through at the same time as a pilot.”

MSU Denver senior Alex “Eddy” Edwards agreed.

“I think this class is super beneficial,” Edwards said. ”Before this, I had no idea about the dumps, the gates, I just thought they (air traffic controllers) were putting us in line (to take off or land) and that was that.”

Obarski, a former air traffic controller with 23 years of experience, said AI could definitely improve predictability and consistency in managing the nation’s growing and congested airspaces.

But could AI ever replace air traffic controllers completely?

“Over time, I think control of this role will continually be diminished,” Obarski said. “You’ll become more of an overseer, a monitor, a manager. We’ve got a command center outside of Washington, D.C., that oversees the whole ATC system … and they’ve got the whole picture.”

Obarski said traffic prioritization, runway changes, and other regional or local airport information could be easily synthesized to increase efficiency and predictability.

And that makes both passengers and airlines happy.

But when asked if AI would ever totally replace air traffic controllers, he isn’t convinced.

“I still think along the way, you’re going to have to have somebody overseeing all of this,” he said.

The Associated Press contributed to this story.