By Ashley Halsey III
Washington Post Staff Writer
Thursday, September 23, 2010; 8:38 PM
Two planes - one carrying 95 people - passed within 100 feet of each other in a cloud bank over Minneapolis this month, the latest in a series of close calls to be investigated by the National Transportation Safety Board this year.
The near-collision was one of more than 35 "category A" errors, the most severe type, logged this year by federal air traffic controllers.
The Sept. 16 near-collision involved an early-morning US Airways flight, bound for Philadelphia with 90 passengers and five crew members, and a twin-engine prop plane. Tower controllers cleared both for takeoff at the same time from adjoining runways at Minneapolis-St. Paul International Airport.
The vision of both pilots was quickly obscured by clouds. Within seconds of takeoff, the tower controller instructed the pilot of the US Airways Airbus 320 to turn left, causing it to pass so close to the cargo plane that the US Airways pilot said he heard the engines of a plane he could not see.
According to the NTSB, which is investigating the incident, collision avoidance software on the Airbus "issued climb instructions to the crew to avert collision."
Federal Aviation Administration spokeswoman Sasha J. Johnson said the agency moved quickly in response to the incident.
"We are very concerned about this event and have already taken steps at the Minneapolis tower to change some runway control procedures and to clarify communication between air traffic controllers," she said. "The FAA is focused on addressing the causes of these events."
The NTSB began scrutinizing near-collisions and other errors involving air traffic controllers this year after concluding there were "repeated failures to report incidents [and] misclassification of incidents" by the FAA.
The cases under review include one in which onboard collision avoidance systems were activated when a commercial flight carrying Rep. F. James Sensenbrenner Jr. (R-Wis.) into Reagan National Airport strayed perilously close to a 22-seat Gulfstream business jet.
The FAA says an increase in the number of errors attributed to air traffic controllers is the result of a new reporting system that encourages controllers to acknowledge their mistakes, shielding them from punishment.
A veteran FAA official who reviewed the radar tape, and who spoke on condition of anonymity because he is not authorized to speak for the agency, said the mistake was the result of a lapse in communication between the north and south tower controllers.
"The weather was crappy and they were turning over the shift," he said. "It was something that went wrong between the two controllers. The north controller told the other controller [about the US Airways flight], and it appears the south controller just forgot about it" while directing the cargo plane.