NEWARK — Air traffic controllers repeatedly rang the alarm about critical safety issues and faced telecommunications outages affecting Newark Liberty International Airport starting last summer – months before widespread delays and flight cancellations at the airport this week, a CNN review of safety reports, air traffic audio and other records found.

One controller wrote in a previously unreported statement in August that only luck had prevented a “catastrophic mid air collision” after a communications breakdown that occurred as multiple planes were routed into the same area to avoid thunderstorms.

And several times over the last year, Newark approach controllers lost radar or radio service, leaving them unable to talk with planes they were tracking. “We just lost all frequencies and communications here,” one controller told pilots in November, according to recordings of air traffic audio.

Those problems appear to have culminated in a loss of radar and radio at the air traffic site for about 90 seconds last week – an episode that led to multiple controllers taking trauma leave from work and resulting in the ongoing Newark meltdown.

Now, controllers and aviation experts say that officials should have heeded the earlier warnings about problems with the intricate and delicate system that guides planes through one of America’s busiest airspaces. Those issues appear to have been exacerbated when Newark’s approach controllers were moved to Philadelphia last summer.

“I’ve never seen anything like this,” said one Newark approach controller who has worked in air traffic control for more than 20 years and requested to remain anonymous because he is a current employee. “We’re playing Russian roulette.”

For decades, air traffic controllers at a facility on Long Island oversaw flights heading to and from the New York City region’s three major airports, John F. Kennedy, LaGuardia and Newark. But the site had struggled with a lack of staffing in recent years, part of a broader shortage of controllers that has hit airports around the US.

In July, the Federal Aviation Administration relocated about two dozen controllers overseeing flights heading to and from Newark. Those controllers shifted from the Long Island facility to a new site in Philadelphia. The change was opposed by some controllers, but the FAA said at the time that it would help address the staffing problems and growing air traffic congestion.

Within weeks, at least a half-dozen controllers reported what they described as serious safety issues caused by failures to collaborate between the two locations about 100 miles apart.

They described the incidents in reports filed with NASA’s Aviation Safety Reporting System, which allows employees in the aerospace industry to anonymously flag safety issues. The reports don’t include identifying information about flights or when exactly incidents happened – and the details in the reports have not necessarily been verified by government investigators.

Still, the reports paint a dramatic picture of controllers seriously worried by what they described as concerning safety practices.

During one incident in August, an air traffic controller with 13 years of experience said that both the Long Island-based controllers overseeing LaGuardia airport and the Philadelphia-based controllers overseeing Newark had re-routed pilots through the same area to avoid thunderstorms. Because controllers overseeing the two airports no longer work “in the same room,” they were struggling to coordinate, leading to an “incredibly dangerous” situation, according to the report.

“The fact that there was no catastrophic mid air collision is nothing short of luck, as these aircraft were converging at high speeds at the same altitude in between dangerous thunderstorms off their left and right sides,” the controller wrote.

Sending the Newark controllers back to Long Island is “the only way to fix the many safety hazards that are attributed to splitting apart this air traffic operation,” they argued.

Another controller at the Long Island site said in a report that the FAA had only provided controllers a single, short briefing on their colleagues’ move to Philadelphia, and that officials had told their team there would be no change to their operations. But on the first day reporting for duty under the new setup, the controller realized that they had to change the way they inputted handoffs of responsibility for aircraft – potentially leading to errors during busy time periods, the report said.

“I am absolutely dumbfounded,” the controller wrote. “The FAA should be utterly ashamed of themselves for failing to properly brief controllers about this change... Not having the EWR controllers in the same room as us is a significant detriment to safety and efficiency.”

A third controller wrote in August that multiple aircraft had entered the airspace overseen by the Long Island facility without the Newark controllers in Philadelphia flagging the flights to their colleagues under a typical procedure.

Moving the controllers “has caused an extremely dangerous situation in the extremely complicated NYC area airspace,” wrote the controller, who had 18 years of experience. “The former EWR area needs to be moved back” to the Long Island facility, they added.

At least one pilot also complained about the impact of the move. In describing an aborted landing at Newark in August, the pilot wrote that having controllers for the airport based in Philadelphia “unnecessarily introduces additional workload for pilots and increases the chances of errors occurring.”

Timothy Johnson, a senior assistant professor of aviation at Hampton University and a former air traffic controller and training manager for the US Air Force, reviewed the reports for CNN and said they should have been a “red flag.”

“I’ve seen firsthand how critical proximity is in maintaining smooth operations,” Johnson said. “When you remove controllers from a shared space — especially in airspace as layered and time-sensitive as the New York metro area — you lose rapid verbal coordination and the kind of instant problem-solving that keeps traffic flowing safely.”

In a statement Wednesday, the FAA did not respond to the criticism from controllers and experts, but said that it was taking “immediate steps to improve the reliability of operations” at Newark by boosting controller staffing and upgrading technology at the Philadelphia location.

While most of the safety reports came within a few weeks after the move to Philadelphia, the new air traffic control site also faced repeated communications outages in the following months, according to audio and other records.

The controllers still rely on radar in Long Island that transmits data to Philadelphia via telecommunications lines. Two air traffic controllers told CNN that the feed had failed at least twice and potentially three times after the move.

FAA air traffic control alerts show the airport repeatedly faced delays that were attributed to equipment or communications problems. In late August, Newark had a ground stop “due to continued equipment issues,” according to an alert. The following month, another ground stop alert cited “equipment / outage” and noted that officials were “evaluating potential radar outage.”

One of the radio outages appears to have taken place on November 6, when controllers overseeing Newark went silent for more than two minutes, according to air traffic audio from the website LiveATC.net and first published in November by the YouTube channel VASAviation. Several pilots noted that they weren’t hearing anything from controllers who were supposed to oversee their approach to the airport. “We have no answer,” one pilot said, adding that “it seems like he’s not talking to anyone.”

Once their radios came back on, controllers appeared to be unsure whether pilots could hear them or not.

“We just lost all frequencies and communications here,” one controller said, later adding, “listen up everybody, real careful – anybody besides United 1560, 1043 or 2192, is there anybody else that can hear me on this frequency?”

One controller who was overseeing the Newark approach at the Philadelphia site that night told CNN there was “mayhem” as controllers scrambled to warn other nearby airports about a FedEx plane that had overshot its Newark flight path into the busy LaGuardia airspace. He said he still has nightmares about all the scenarios that could have unfolded during the outage.

In a statement, FedEx said its crew “complied with air traffic control instructions before landing safely,” adding that the company is “committed to maintaining the highest safety standards.”

Michael McCormick, an aviation professor at Embry-Riddle Aeronautical University, said these communication failures are much more concerning to him than the reports made during the summer of the relocation – which he chalked up largely to growing pains.

The November outage should have “been a warning,” McCormick said. “To lose radio communication for several minutes would mean that something needs to be looked at and looked at in detail and resolved.”

The repeated communication problems continued into the new year. In February, an FAA alert stated that “users can expect arrival delays / airborne holding into the Newark Airport of up to 45 minutes due to frequency and communication line issues.” Another alert about delays due to “communications issues” was issued in early April.

Finally, on April 28, the Newark controllers lost radar service for about 90 seconds and were unable to communicate with pilots for about a minute, a source with knowledge of the situation told CNN. The breakdown was caused by failures in the copper wiring that transmits information from Long Island to Philadelphia, a separate source said.

After the incident, at least three controllers, one supervisor and a trainee took 45 days of mental health leave. That led to even more significant understaffing at the Newark approach control site, requiring airlines to delay or cancel hundreds of flights over the last week – and turning a situation that had been causing consternation in the insular air traffic controller community into a national headache.

The FAA said in a statement Wednesday that it plans to add three new “high-bandwidth telecommunications connections” from New York to Philadelphia, replace copper lines with fiber-optic technology, and deploy a backup system to provide more speed and reliability. In the longer term, Transportation Secretary Sean Duffy has promised a complete reconstruction of the nation’s air traffic control system that he says will be more reliable than the current antiquated technology.

But Johnson, the aviation expert, said that the FAA should re-evaluate the decision to move controllers to Philadelphia in the first place.

“This current configuration appears to be increasing complexity without a sufficient safety margin,” he said. “Relying on human heroics to patch over structural vulnerabilities is not how we maintain safety.”

The Newark approach controller who was on duty during the November incident told CNN he works in constant fear of a fatal crash under his watch. He said the FAA ignored warnings about the safety issues, and he argued that the failures could have been avoided if the agency had listened to controllers who had objected to the move.

“At the end of the day, I just want equipment that works,” he said. “I don’t want to kill people. That’s my biggest fear.” — CNN