The heads of the largest airlines in the country penned an open letter Wednesday calling on Congress to fund a major modernization of the U.S.'s antiquated air traffic control system that has contributed to heightened safety concerns and rampant airport delays.

"The current system is failing Americans," the group of 10 company CEOs wrote in a joint letter that was posted on the Airlines for America (A4A) industry collective's website. "The United States needs and deserves a world-class aviation system."

A4A represents American Airlines, Delta, United, Southwest, JetBlue, Alaska Airlines, Hawaiian Airlines and Atlas Air, as well as global shipping companies FedEx and UPS.

Representatives from the airlines have been holding regular meetings with the Federal Aviation Administration (FAA) in recent weeks to discuss various concerns and steps forward to address them.

“Commercial airline travel remains the safest form of transportation in world history,” FAA Acting Administrator Chris Rocheleau said in a statement Wednesday. “But the last three months drove home that we need to do more, we need to be better, and we need to do it together.”

The FAA issued an interim order on Tuesday reducing the flight arrival and departure rate at Newark Liberty International Airport in New Jersey, after staffing and equipment issues spiraled into mass delays.

"Our goal is to relieve the substantial inconvenience to the traveling public from excessive flight delays due to construction, staffing challenges, and recent equipment issues, which magnify as they spread through the National Airspace System," Rocheleau said.

Transportation Secretary Sean Duffy has been on an aggressive push to resolve a long-standing air traffic controller staffing shortage, but outdated equipment has compounded concerns in recent years.

The airline companies wrote in their joint letter that it's on Congress to pay for a new multi-billion-dollar, state-of-the-art air traffic control system.

"Aviation is an industry of innovation, and the FAA needs the ability to procure 21st century equipment and transformational technology solutions to efficiently and strategically handle 21st century flight volumes," they wrote.

Republicans, who hold narrow majorities in the House and Senate, are trying to hash out a spending plan for the coming year that will cover most of President Trump's sweeping policy agenda in what Trump has dubbed the "One Big, Beautiful Bill."

The House Budget Committee's version of the reconciliation bill includes just over $12 billion for the FAA technology upgrade, which the airlines deemed a "solid down payment" toward the full overhaul needed.