U.S. Transportation Secretary Pete Buttigieg said Wednesday that the country's air system was skirting disaster in the wake of multiple near-miss aviation incidents in the past year.

Speaking at an air safety summit convened by the Federal Aviation Administration, Buttigieg said that while the U.S. continues to enjoy "the safest and most complex system in the world," there are indications that the system is under strain.

"We can't wait for the next catastrophic event when we can see the warning signs today," he said.

The summit comes amid a recent spate of runway incursions and other near disasters in the skies that have shaken the public.

Buttigieg was joined by Jennifer Homendy, chair of the National Transportation Safety Board, who cited six serious runway incursions since January, including an incident at JFK Airport in New York City involving an American Airlines flight narrowly avoiding an outbound Delta Air Lines flight, and a landing FedEx Cargo plane coming within 100 feet of a departing Southwest Airlines flight at Austin-Bergstrom International Airport in Texas.

The NTSB also continues to investigate two wrong-runway incidents from last June, in Burbank, California, and Pittsburgh, Homendy said.

And it is also looking into two episodes in Hawaiian airspace — one involving severe turbulence aboard a Hawaiian Airlines flight that injured 25 people, and another that saw a United Airlines flight plunge within several hundred feet of the Pacific Ocean.

Homendy said there had been "far too many close calls and near collisions" recently. The incidents, she said, should serve as a "wake-up call" for the industry — yet too often actions are taken only after a disaster has occurred, she said.

She also hit out at long-outstanding recommendations, including a 23-year-old request for technology that would help avoid runway collisions, that have yet to be implemented.

In his February letter convening the summit, acting FAA Administrator Billy Nolen said he hoped it would serve as a "call to action" to implement changes to further strengthen U.S. aviation.

On Wednesday, Nolen cited the recent spate of near-misses, as well as unruly passenger incidents "that defy logic," as posing threats to air safety.

"These events are concerning," Nolen said. "They are not what we come to expect during a time of unprecedented safety in the U.S. aviation system."