NTSB Identification: CHI07FA184A
Scheduled 14 CFR Part 121: Air Carrier UNITED AIR LINES INC
Accident occurred Wednesday, June 27, 2007 in Chicago, IL
Probable Cause Approval Date: 03/23/2009
Aircraft: BOEING 777-222, registration: N213UA
Injuries: 501 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

Due to a weather hold, a McDonnell Douglas MD 83 was given clearance by Air Traffic Controllers (ATC) to park in a hold pad. A Boeing 777-222 was given similar ATC instruction. Rain and a micro burst were reported in the area obscuring visibility while taxiing. The runway 9R hold pad chart indicated that "pilots exercise caution taxiing past hold pad with parked aircraft - maintain centerline. Entire aircraft must be contained inside pad boundary line/lights." The 777-222 captain stated that he maintained the taxiway centerline while taxiing. The 777-222's flight crew used flight handbook reference points to remain clear of the parked airplanes. However, the 777-222's right wing impacted the MD 83's rudder. Wreckage on the ground was consistent with the MD 83 not fully parked within the hold pad. An ATC representative reported that ATC had received no guidance from the airport certificate holder on the entry and exit of airplanes on the 9R hold pad. The area encircling the hold pad was marked as taxiway. Taxiway Mike (M) borders the south area of the 9R hold pad and taxiway Kilo (K) borders the north area of the 9R hold pad.

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

The 777-222's flight crew not maintaining clearance from the parked/standing MD 83 and the airport not coordinating the taxi chart instructions with air traffic control. Contributing to the accident was the MD 83's flight crew not following the taxi chart instructions to fully park within the pad and the reduced visual lookout due to the weather.

Full narrative available

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