A veteran New Jersey air traffic controller has revealed he scribbled handwritten flight details in a notebook amid fears his radar equipment would go dark as he was trying to avoid a recent nose-to-nose midair collision.

Jonathan Stewart 45, was working at the Philadelphia facility that oversees airspace near the troubled Newark Liberty International Airport on May 4 when the near-miss unfolded, the Wall Street Journal reported.

“I don’t want to be responsible for killing 400 people,” Stewart said in a lengthy interview — as he detailed the frightening ordeal that resulted in him taking stress leave.

Stewart said he took the dramatic step of writing down callsigns for the two planes given that radar systems at the facility had failed just days earlier — wreaking havoc at the major international hub and causing mass cancellations.

The midair saga involved a business jet that had just taken off from the Morristown Airport and a small jet that was coming from nearby Teterboro Airport.

Stewart, who is a supervisor at the facility and says he’ll make $450,000 this year, recalled seeing the two jets speeding directly toward each other on his radar scope at the same altitude — potentially seconds away from colliding.   

“I had been working in the operation for roughly three hours-ish at the time of the incident. Typically, I try not to work myself or anyone else longer than two hours. It has just been my experience that after that two-hour mark, your mental acuity begins to diminish a little bit because it’s fatigue,” he said.

“In my situation, I was getting tired. I was having to utilize a combination of radar and non-radar rules that I basically just made up on the fly to separate aircraft in such a way that I could be prepared for losing radar.”

“That increased my workload that led to me having a close call — so a nose-to-nose situation,” he added.

The ordeal, which he blamed in part on understaffing and equipment reliability, left him so traumatized that he has been out on stress leave since.

“I had a really bad error. You know, I could have, you know, done something terrible,” he said. “That part for was extremely stressful to me and that’s why I’m taking some time off.”

Elsewhere in the interview, Stewart blasted suggestions that air traffic controllers walking off the job were to blame for the woes that have plagued Newark Airport of late — including multiple instances when radars went down.  

In the wake of one of the recent ordeals, United Airlines chief executive Scott Kirby said the airport was struggling after controllers walked off the job.

“Hopefully he misspoke because the controllers did not walk off the job. Walking off the job implies that of their own free will, left and refused to do their job. There’s not a single controller in Newark Area C — to the best of my knowledge — that does not love their job,” he said.

“We would like to have more resources to effectively do our job. To say that someone would basically game the system and take trauma leave when they were not traumatized is insulting at best and just quite frankly misinformed.”

“They had to be taken out of position and relieved of duty because they were not mentally fit to do it anymore at that point because of the trauma that was involved,” he added.

Stewart spoke out after Transportation Secretary Sean Duffy last week unveiled plans to revamp the nation’s troubled air travel system, detailing a multibillion-dollar overhaul to replace the aging air traffic control equipment.

The Transportation Department plans to ask Congress for billions and billions of dollars to replace 618 radars, install 4,600 new high-speed connections and upgrade all the computers that controllers use.

Federal Aviation Administration officials told a congressional hearing Wednesday that it would take another year or more to update aging infrastructure and complete recruitment for controllers.

The FAA is still short roughly 3,000 air traffic controllers and is in the process of updating copper telecommunications wires with a brand-new fiber-optic network.