Federal Aviation Administrator Randy Babbitt said Friday that he will revamp air traffic control guidelines nationwide after an incident in which the lone supervisor on duty in the Reagan National Airport tower slept while two airliners landed on their own.

“Effective immediately, we are instituting an interim plan to ensure we do not repeat another situation like the one at Reagan National Airport Wednesday morning,” Babbitt said. “I have ordered a nationwide review of the air traffic control system. . . . I am determined to make sure we do not repeat Wednesday’s unacceptable event.”

Babbitt said he would order radar controllers who guide planes as they descend from cruising altitude to confirm that controllers in airport towers are prepared to handle incoming flights before handing them off.

Under current procedures, those controllers turn planes toward their final approach and then tell pilots to contact the tower for guidance onto the runway.

Babbitt also said he would instruct controllers to offer the pilots an option to land elsewhere if a control tower is unresponsive for any reason.

Also on Friday, the National Air Traffic Controllers Association urged that staffing be doubled at other airports that have one person in the tower during overnight shifts. The controllers union said those include San Diego; Sacramento; San Juan, Puerto Rico; Tucson; Orlando; Reno, Nev.; and Burlington, Vt.

“We believe one-person mid[night] shifts, and one-person shifts anytime, are unsafe,” said Doug Church, a union spokesman. “We must have two. Some large airports currently have more than that. . . . [Chicago’s] O’Hare has three on its mid shift, plus a supervisor makes four total personnel.”

Most major airports that operate 24 hours a day have two controllers in the tower for the midnight-to-6 a.m. shift., Church said. Dulles International Airport and Baltimore-Washington International Marshall Airport have two, as do the major airports in New York, Newark and Boston.

U.S. Transportation Secretary Ray LaHood immediately ordered a second controller into the National tower for the midnight to 6 a.m. shift after Wednesday’s incident.

When pilots were unable to contact the National tower just after midnight Wednesday, they conferred with a controller at the Potomac Terminal Radar (TRACON) facility, who advised them that the tower appeared to be unmanned. He informed them that if they opted to land there, they should use procedures appropriate for an “uncontrolled” airport.

Controllers have been operating under a directive issued in 1999 by Jeff Griffith, then the FAA program director for air traffic operations.

Griffith wrote that controllers have no legal basis for withholding landing clearance because a tower isn’t functioning but must “inform the pilot of any abnormal conditions.”

On Thursday, Babbitt suspended the veteran supervisor who fell asleep, saying he was “personally outraged” after the two planes, carrying a total of 165 people, landed without help from the control tower.

The supervisor was drug-tested by federal authorities before being suspended from his job, federal officials said. The FAA declined to confirm the testing or comment on the results.

The National Transportation Safety Board continued its formal investigation into the incident Friday, and the House transportation committee also plans to conduct a formal review.

The issue of tower staffing arose five years ago, when Comair Flight 191 turned onto the wrong runway at the Lexington, Ky., airport. The runway was too short, and the plane crashed on takeoff, killing 47 passengers and two of the three crew members.

Investigators determined that there was only one controller in the tower, a violation of that airport’s policy.

Until LaHood ordered otherwise late Wednesday, the National tower had been staffed by one air traffic controller from midnight to 6 a.m. As the two planes approached to land early Wednesday, the on-duty controller did not respond to pilots’ requests for landing assistance or to phone calls from controllers elsewhere in the region, who also used a “shout line,” which pipes into a loudspeaker in the tower, internal records show.

The planes — an American Airlines Boeing 737 flying from Miami with 97 people on board, and a United Airlines Airbus A320 flying from Chicago with 68 people on board — landed safely within minutes of each other, just after midnight.

Because the controller was not available, the planes’ pilots took matters into their own hands, broadcasting their progress as they approached and landed. They also were communicating with radar controllers at a separate facility in the region that does not handle landings.

When the tower supervisor first came back on the radio Wednesday morning, in a conversation with a pilot he identified the problem that caused the silence as a “stuck mike.”

In the unlikely scenario of a radio failure, the tower is equipped with a light system visible to arriving pilots. If the runway was clear to land, the tower controller would flash a green light. If another plane or an airport vehicle was on the runway, the controller would give a red signal.

The lights were not put to use Wednesday morning, according to a review of radio transmissions and another FAA source familiar with the incident.

“Even if he got flustered and forgot about the lights as the first plane approached, you would think he’d come to his senses and use it after one plane landed in front of him and he saw another coming in,” said the source, who spoke on the condition of anonymity because he also is not authorized to speak for the agency.

Babbitt saluted the TRACON backup Thursday for stepping in to help the pilots land.

“Fortunately, at no point was either plane out of radar contact, and our backup system kicked in to ensure the safe landing of both airplanes,” Babbitt said.