NTSB Identification: CHI93IA126.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Scheduled 14 CFR operation of SIMMONS
Incident occurred Saturday, March 13, 1993 in CHICAGO, IL
Probable Cause Approval Date: 09/30/1994
Aircraft: ATR ATR 42, registration: N426MQ
Injuries: 3 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

RUNWAY CONFIGURATION WAS IN THE PROCESS OF BEING CHANGED FROM ARRIVALS & DEPARTURES ON RUNWAYS 32L & 32R TO DEPARTURES FROM 32R & ARRIVALS TO 32L. SIMMONS 4321, AN ATR-42, WAS CLEARED FOR TAKEOFF BY THE NORTH LOCAL CONTROLLER (NLC) FROM RUNWAY 32R & SUBSEQUENTLY WAS INSTRUCTED TO TURN LEFT HEADING 270 DEG. THE SOUTH LOCAL CONTROLLER (SLC) THEN CLEARED UNITED 1206, A DC-10, FOR TAKEOFF FROM RUNWAY 32L. WHEN UNITED FLIGHT 1206 BECAME AIRBORNE, SIMMONS 4321 HAD ALREADY STARTED THE LEFT TURN WHICH PUT THE AIRCRAFT IN THE DEPARTURE PATH OF FLIGHT 1206. SEPARATION WAS REDUCED TO ZERO FEET VERTICALLY & .5 MILE LATERALLY. THE NLC SAID HE HAD A DISCUSSION WITH THE AREA SUPERVISOR REGARDING DEPARTURE HEADINGS (IF THERE WERE NO DEPARTURES ON RUNWAY 32L); IN THE CONVERSATION, HE THOUGHT THE AREA CONTROLLER HAD INDICATED THAT A LEFT TURN WOULD BY ALRIGHT. HOWEVER, THE AREA SUPERVISOR DENIED DISCUSSING A LEFT TURN; HIS RECOLLECTION WAS DISCUSSING THE USE OF A 340 DEGREE HEADING VERSUS A 350 DEGREE HEADING TO PROTECT FOR MISSED APPROACHES.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

AN IMPROPER CLEARANCE BY THE NORTH LOCAL CONTROLLER, WHICH RESULTED IN A FAILURE TO MAINTAIN PROPER IFR SEPARATION. A FACTOR RELATED TO THE INCIDENT WAS: INADEQUATE COORDINATION AMONG THE TOWER PERSONNEL.

Full narrative available

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