Transportation Secretary Sean Duffy at a press conference Thursday called for Congress to allocate tens of billions of dollars to overhaul America’s strained air traffic control system and replace its antiquated technology.

Duffy said his agency would build a new air traffic control system “in three to four years” but needed Congress to make that happen, adding, “we need all of the money up front.”

President Donald Trump briefly joined the press conference by phone, saying his administration would award “one big, beautiful system” to a single contractor, replacing the FAA’s outdated system with “all brand new” technology.

The aging ATC system is “an untenable risk to safety” and a huge investment is “absolutely necessary to ensure safety in our skies,” Jennifer Homendy, the chair of the National Transportation Safety Board, told reporters, repeating a previous urgent call for modernization.