The US National Transportation Safety Board is investigating an operational error that resulted in two American Airlines jet aircraft coming within "0.35nm(650m) of each other horizontally as they approached parallel runways at Chicago O'Hare International airport in visual weather conditions on 1 June.

Due to an "air traffic control oversight", the NTSB says, Flight 879, a Boeing MD-82, overshot the final approach course for Runway 28 while being vectored and continued northbound, "conflicting" with Flight 93, a Boeing 767 on final approach to Runway 27L.

"According to preliminary Federal Aviation Administration data, lateral separation decreased to 0.35nm and vertical separation was 0ft," says the NTSB.

 © American Airlines

Source: Flight International