MCDONNELL DOUGLAS MD80 near Chicago, IL — 2009-06-01

Probable cause

The Chicago TRACON West Arrival controller's omission of a required clearance, resulting in AAL 879 overshooting the final for runway 28 and losing separation with AAL 93.

NTSB narrative

While on approach to Chicago-O'Hare International Airport, American Airlines flight 879 (AAL 879) was being radar-vectored to the final approach course for runway 28 and American Airlines flight 93 (AAL 93) was on a straight-in approach to runway 27L. Both aircraft were under control of Chicago Terminal Radar Approach Control. Because of an air traffic control oversight, AAL 879 overshot the final approach course for runway 28 and continued northbound, conflicting with AAL 93 on the runway 27L final. According to preliminary Federal Aviation Administration data, lateral separation decreased to 0.35 nautical mile and vertical separation was 0 feet before the conflict was resolved. There were no injuries or damage reported as a result of the incident, which occurred in visual meteorological conditions, with 10 statute miles of visibility and a 5500-foot ceiling.

NTSB coding

• Near midair/TCAS alert/loss of separation · Approach-IFR final approach