SUMMARY On May 16, 2011, at 0934 central daylight time, a near mid air collision (NMAC) occurred at Chicago O’Hare International Airport (ORD) when SkyWest Airlines flight 6958 (SKW6958), a Bombardier CRJ2 en route from Muskegon County, Michigan to ORD passed in close proximity to ExpressJet Airlines flight 6075 (BTA6075), an Embraer 145 departing from ORD to Buffalo, New York. According to recorded FAA radar data, SKW6958 crossed runway 32L about 275 feet above and 480 feet behind BTA6075. Both aircraft were under control of ORD air traffic control tower (ATCT) at the time of the incident. There was no damage reported to either aircraft, or any injuries to passengers or crew. HISTORY OF FLIGHT SKW6958 was a scheduled 14 Code of Federal Regulations Part 121 (14 CFR part 121) passenger flight operating from Muskegon County, Michigan, to Chicago, Illinois. The flight was on a visual approach to runway 9R at Chicago O’Hare International Airport. The pilot contacted the ORD North Local Controller (NLC) at 0934:36, reporting in at LANCE. The controller transmitted to the pilot, “SKW6958 O’Hare Tower, runway 9 right clear to land, wind 020 at 14 traffic departing prior to your arrival,” and the pilot acknowledged. BTA6075 was a scheduled 14 CFR part 121 passenger flight operating from Chicago O’Hare International Airport to Buffalo, New York. The pilot was instructed to taxi to runway 32L for departure. At 09:34:53, the Third Local Controller (3LC) cleared BTA6075 to line up and wait on runway 32L. At 0935:37, BTA6075 was cleared for takeoff, “...don’t delay roll.” At 09:36:33, the 3LC controller transmitted, “aw [expletive].” At 0936:34 the NLC issued a go around to SKW6958. The NLC controller then continued, “SKW6958 climb and maintain four thousand, helicopter traffic just off the departure end low level.” At 09:36:45 the pilot of BTA6075 transmitted “What the [expletive] was that?” followed by “where do you want 6075 to go now?” The 3LC instructed BTA6075 to turn right heading 020 and to remain this frequency. BTA6075 responded with “what was that?” and the controller responded “sorry about that.” The remainder of the ATC handling was routine. The tower supervisor relieved the 3LC controller from position at 0937:00 and logged the incident in the Daily Record of Facility Operations. RADAR DATA Radar data for this report was obtained from the ORD Airport Surface Detection Equipment-X system. Graphics of the two flights as they approached the intersection and after passing the intersection of runway 32L/9R are contained in the ATC Group factual report and have been added to the docket. For further information, see the Air Traffic Control Group Chairman's Factual Report in the docket for this case.