WASHINGTON (CNN) -- The Federal Aviation Administration Tuesday ordered a nationwide halt to "opposite direction" runway operations, in which planes arrive on runways in one direction and depart in the other, as the result of an investigation into last week's incident at Reagan National Airport involving three planes which came dangerously close.
FAA Acting Administrator Michael Huerta ordered the temporary halt, saying the agency discovered it has "no standard protocol" for switching from a one-way runway traffic pattern to the less common two-way pattern. The lack of a standard protocol likely contributed to the July 31 mishap, he said.
During last week's incident, a southbound US Airways regional jet arriving at Reagan came in close proximity to two northbound jets taking off from the airport. At their closest, two planes came within 0.82 nautical miles, less than the required 3.0 nautical miles.
In a memo released Tuesday, Huerta repeated his initial statement that the aircraft were never on a head-to-head collision course. And he again blamed the mishap on a miscommunication between the Potomac TRACON, a regional radar facility, and managers at Reagan's control tower.
But the investigation has altered one key understanding of the incident. Department of Transportation and FAA officials originally told reporters that the misunderstanding occurred as controllers "flipped" the direction of the airport, switching all traffic from a northbound direction to a southbound direction. Now Huerta says the regional TRACON controller intended to change the direction of only the arriving aircraft, allowing "opposite direction" traffic on the runway. Controllers sometimes allow two-way traffic to comply with noise restrictions or to accommodate cargo operations, he said. Takeoffs and landings are staggered to avoid collisions.
While changing from one-way traffic to two-way traffic encompasses many of the same procedures as flipping an airport, "there is no standard protocol in place," Huerta wrote. "We believe this contributed to the miscommunication."
Huerta said he is halting two-way runway traffic "out of an abundance of caution," and that the FAA expects to have standard procedures in place within a month.
Huerta said the Reagan incident also raised the issue that the FAA's front-line managers are managing administrative tasks in addition to overseeing tower operations.
"We need to be sure that they are solely focused on the operations in the facility and not handling administrative duties" during busy times, he wrote.
The 2 p.m. incident involved three aircraft: Chautauqua Airlines 3072, Republic Airlines 3329 and Republic 3467. All three aircraft were operating as US Airways Express.
All reached their destinations safely.