The Trump administration proposed a major overhaul of the U.S. air traffic control system on Thursday in the wake of recent deadly plane crashes and technical failures that have put a spotlight on the outdated network.

The plan calls for six new air traffic control centers, along with technology and communications upgrades at all of the nation’s air traffic facilities over the next three years, said Transportation Secretary Sean Duffy.

President Donald Trump’s own policies have prompted departures of key staff and hurt morale at the aviation agency, complicating multi-billion dollar modernization plans.