WASHINGTON (WTVO) — Transportation officials gathered in Washington D.C. on Wednesday for an emergency Federal Aviation Administration safety summit.

The summit follows an alarming string of planes almost colliding at several of the nation’s busiest airports. The National Transportation Safety Board (NTSB) is investigating at least six near-collisions between aircraft.

Some experts said that these near misses are a sign of an overburdened and under-staffed air safety system.

Aging infrastructure is also a concern, highlighted by January’s failure of a nation-wide pilot communication system that left all U.S. planes grounded for nearly a day.

“These recent events must serve as a wake-up call for every single one of us before something more catastrophic occurs,” said Jennifer Homendy, NTSB chair.

“The biggest mistake we can make as an industry is to become complacent,” added Bily Nolen, acting FAA administrator.

The NTSB has called for the installation of new safety technology to help reduce the chance of runway incursions. Those systems have only been placed at 40 of the nation’s 5,000 public airports so far.