NTSB CAROL · Event
Event OPS11IA552
Aircraft involved
Probable cause & findings
The air traffic controller’s failure to adhere to runway separation requirements and his issuance of an improper takeoff clearance. Contributing to the incident was the controller's failure to recall that there was an arrival inbound to a crossing runway.
Factual narrative
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. A near-midair collision occurred between a Bombardier CRJ2 landing on runway 9R and an Embraer ERJ-145 regional jet departing from runway 32L. The CRJ2 passed 480 feet behind and 275 feet above the ERJ-145. According to the tower air traffic controller responsible for operations on runway 32L, he scanned the final approach course for runway 9R to look for conflicting traffic and saw the approaching CRJ2. However, he then forgot about the arrival and cleared the ERJ-145 for takeoff. The controller was unable to provide any explanation for the lapse. The airport was not equipped with automated assistance for detecting conflicts between departures and arrivals on crossing runways such as these. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).
- C Personnel issues-Action/decision-Action-Incorrect action selection-ATC personnel - C
- C Personnel issues-Action/decision-Action-Forgotten action/omission-ATC personnel - C
- C Personnel issues-Action/decision-Action-Incorrect action selection-ATC personnel - C
- C Personnel issues-Action/decision-Action-Forgotten action/omission-ATC personnel - C
Verbatim from NTSB's published report. Source file
NTSB_2011_OPS11IA552.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (midair collision). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- Embry-Riddle Scholarly Commons 2024 · Journal article (IJAAA)
Airspace Saturation and Midair Collision Risk: A Case Study at a Class D Airport
Near midair collisions are precursor events to actual collisions and may be an indicator of risk. While previous studies have used reports of near midair collisions to relate factors such as airspace …
- NASA NTRS 2023 · Presentation
The Viability of See-and-Avoid for Midair Collision Avoidance for Urban Air Mobility (UAM)
Urban Air Mobility (UAM) is an emerging aviation concept that could supplement today’s ground and air transportation systems.
- NASA NTRS 2023 · Presentation
The Viability of See-and-Avoid for Midair Collision Avoidance for UAM
Urban Air Mobility (UAM) is an emerging aviation concept that could supplement today’s ground and air transportation systems.
- NASA NTRS 2019 · Other - Patent
Apparatus for aiding a pilot in avoiding a midair collision between aircraft
An apparatus for aiding a pilot in avoiding a midair collision between aircraft is described. A protected aircraft carries a transmitter, a transponder, a receiver, and a data processor; and an intrud…
- Embry-Riddle Scholarly Commons 2018 · Journal article (IJAAA)
Evaluating Small UAS Near Midair Collision Risk Using AeroScope and ADS-B
As small unmanned aircraft systems (sUAS) continue to proliferate in the National Airspace System (NAS), near midair collisions are becoming more common.
- NASA NTRS 2011 · Reprint (Version printed in journal)
Midair collisions - The accidents, the systems, and the Realpolitik
Two midair collisions occurring in 1978 are described, and the air traffic control system and procedures in use at the time, human factors implications and political consequences of the accidents are …
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