CHICAGO – The planned shutdown of nearly 240 air traffic control towers across the country under federal budget cuts will strip away an extra layer of safety during takeoffs and landings, leaving pilots to manage the most critical stages of flight on their own.

The towers slated to close are at smaller airports with lighter traffic, and all pilots are trained to land without help by communicating among themselves on a common radio frequency. But airport directors and pilots say there is little doubt the removal of that second pair of eyes on the ground increases risk and will slow the progress that has made the U.S. air system the safest in the world.

It’s not just private pilots in small planes who stand to be affected. Many of the airports in question are serviced by major airlines, and the cuts could also leave towers unmanned during overnight hours at some big-city airports such as Chicago’s Midway and General Mitchell Airport in Milwaukee. The plans have prompted airlines to review whether the changes might pose problems for commercial service that could mean canceling or rescheduling flights.