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

Secretary Sean Duffy on Thursday will urge Congress to approve

billions of dollars to replace aging radar, telecommunications

equipment, towers and other facilities in an overhaul of the

crumbling air traffic control system, airline officials said.

Duffy, who will be joined by the CEOs of the five largest

airlines and senior executives at Boeing ( BA ) and Airbus

, will not set a precise figure for the overhaul that he

has previously estimated will cost "tens of billions of

dollars."

Also attending will be relatives of some of the 67 people

killed on Jan. 29 in the mid-air collision between a U.S. Army

helicopter and an American Airlines ( AAL ) regional jet.