WASHINGTON — The Federal Aviation Administration announced measures today to improve runway safety, including the installation at major airports of lights that signal pilots when a runway is safe to enter.

The announcement by Acting FAA Administrator Robert Sturgell comes amid criticism of FAA officials by federal lawmakers and others over an alarming rate of runway incursions at airports.

"Severe runway incursions are down," Sturgell said in remarks prepared for delivery at a morning press conference. "And, we're putting technology and procedures in place to keep it that way. We're making changes on the runway and in the cockpit that are going to make a significant difference."

Sturgell was also expected to face questions about two near-collisions in less than a week at John F. Kennedy International Airport in New York. The near-collision on Friday — involving a Delta Air Lines and a Comair flight — prompted the agency to immediately change the way takeoffs and landings are sequenced on perpendicular runways.

In December, congressional investigators warned that air travelers face a high risk of a catastrophic collision on U.S. airport runways because of faltering federal leadership, malfunctioning technology and overworked air traffic controllers.

Since 1990, 63 people have died in six U.S. runway collisions. Monday's announcement was aimed at reducing runway incursions, defined as an event in which any aircraft, vehicle or person intrudes in space reserved for takeoff or landing.

The FAA's previous definition of "runway incursion" did not did not include serious runway errors such as the one that led to the Aug. 27, 2006, crash of a Comair jet in Lexington, Ky. The pilots mistakenly traveled down a runway too short for takeoff and the aircraft crashed, killing 49 of the 50 people aboard.

The runway safety system announced Monday involves lighting systems to be installed at 21 airports over the next three years. The lights change color to signal when a runway is safe to enter or cross, according to a description posted on the FAA's Web site.

Airports selected for the program are Atlanta, Baltimore-Washington, Boston, Charlotte, Chicago-O'Hare, Dallas-Ft. Worth, Denver, Detroit, Ft. Lauderdale, Houston Intercontinental, John F. Kennedy, LaGuardia, Las Vegas, Los Angeles, Minneapolis, Newark, Orlando, Philadelphia, San Diego, Seattle and Washington-Dulles.