Snoozing controllers, geriatric radars and incessant radio transmissions no longer will be part of the U.S. air-traffic control system, if government and industry advocates of change have their way.

Long-pending modernization plans call for a satellite-based navigation network to replace the aging, hard-to-maintain ground-based equipment that controllers now use to handle all aircraft. The shift could cost the government $20 billion and take 15 years or more, particularly in today's deficit-conscious budget environment. For...