WASHINGTON, May 8 (Reuters) - U.S. Transportation

Secretary Sean Duffy unveiled a plan on Thursday to modernize

the aging U.S. air traffic control system at a cost of tens of

billions of dollars to address airport congestion, flight delays

and safety.

"This is bold. This is going to be challenging but we

absolutely can do it," Duffy said at an event announcing the

effort, estimating the project would take three to four years.

The program will involve upgrading outdated radar and

telecommunications systems, air traffic control towers and other

facilities as well as increasing staffing of air traffic

controllers.

The Federal Aviation Administration plans to replace 618

radars, install anti-collision tarmac technology at 200

airports, build six new air traffic control centers and expand

its ADS-B network of real-time aircraft traffic information.

"It's long past time when we need to fix this problem,"

Acting FAA Administrator Chris Rocheleau said.

Duffy, joined by five airline CEOs and senior executives at

Boeing ( BA ) and Airbus, did not set a precise figure

for the overhaul that he has previously estimated will cost

"tens of billions of dollars."

The FAA's air traffic control network's woes have been years

in the making, but a rush of high-profile mishaps, near-misses

and a catastrophic crash in January have spiked public alarm and

prompted new calls for action.

Also attending the announcement were relatives of some of

the 67 people killed on January 29 in the mid-air collision

between a U.S. Army helicopter and an American Airlines ( AAL ) regional

jet.

Duffy has said he wants new funding for airport equipment

to prevent near-miss incidents and new incentives to boost air

traffic controller hiring, which is 3,500 short of targeted

staffing.

President Donald Trump during his first term in 2017

proposed privatizing air traffic control, but Congress never

acted on his proposal.

Airlines and others are expected to call for around $31

billion in spending. A U.S. House panel has proposed $12.5

billion in initial spending on air traffic control reform,

including $2.5 billion for air traffic tower and contract-tower

replacements.