CHI07FA184

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.

History of flight

On June 27, 2007, about 1545 central daylight time, a Boeing 777-222, N213UA, sustained minor damage during its taxi into the 9R holding pad area at the Chicago O'Hare International Airport, Chicago, Illinois, when it collided with a standing McDonnell Douglas MD 83, N9630A, which resulted in substantial damage to the MD 83. Both airplanes were operating under Title 14 Code of Federal Regulations Part 121 as scheduled-domestic passenger flights. Visual meteorological conditions prevailed at the time the accident. The 777-222's 2 pilots, 11 flight attendants, 1 non-revenue passenger, and 347 passengers sustained no injury. The MD 83's 2 pilots, 3 flight attendants, and 135 passengers sustained no injury. The 777-222 was United Airline's (UAL) flight 149 destined for the San Francisco International Airport, near San Francisco, California, and the MD 83 was American Airline's flight 1817 destined for the Seattle-Tacoma International Airport, near Seattle, Washington.

The MD 83 captain's statement indicated that a weather-related ground stop occurred and the flight was instructed by air traffic control (ATC) to follow a UAL Boeing (B)757 to the 9R hold pad. The MD 83 captain, in part, stated;

There were already eight airplanes in the north sector of the pad, all

pointed in a southeast direction. Several airplanes had established a

line in the south sector with the nose of the airplane in a northeast

direction.

As we proceeded westbound on M taxiway, I observed the UAL B757

make a right turn to continue the line of aircraft that had formed.

When the B757 stopped, he blocked our access due to inadequate

wing tip clearance. A request was made to the tower to ask UAL to

move further northeast. I then maneuvered to a position

approximately parallel and abeam the UAL B757, stopped, and set

parking brakes.

An AE [American Eagle] RJ was next in line and was in our 8 to 9

o'clock position. In trail, was a UAL B777 (N213UA). ...

As we prepared to shut down the left engine, our airplane rocked

from side to side as if hit by the wake of a passing boat. I knew

what had happened given the proximity of the B777, and it was

confirmed by an adjacent aircraft (I believe the AE crew on our

left side).

The MD 83 first officer's statement, in part, stated, "We were facing northeast, as instructed by ATC, within the confines of the painted markings of the southern 'penalty box' in the 9R pad."

According to 777-222 captain, he reported that he was taxiing the airplane to hold in the 9R pad due to a weather hold. He indicated he that was the third airplane in a line of airplanes that were given ATC clearance to taxi west on taxiway Mike (M) behind a south line of airplanes in the hold pad and to join that south line at its west end. The 777-222 captain's statement, in part, stated:

There was about 10 AC [aircraft] on the north side of the pad

facing southeast and ATC was adding AC in a parallel line on the

south side of the pad facing northeast. There were about 8 AC in

the south line when I entered the pad. ...

There was a text book micro burst to our right just north of the 9R

pad blowing dirt and debris outward. The skies were dark and

gloomy with diffused sunlight penetrating the haze around the TRW

[thunderstorm.] It began to rain. Just as I joined taxiway Mike the

line of taxiing AC came to a stop. It was obvious one of the AC in

the south line was going to have to pull up. ...

When it was clear for our AC to taxi we slowly proceeded westbound

on taxiway Mike using the flight handbook reference diagrams and

my experience to ensure right wingtip clearance from the back of the

AC in the south line. ... By now water was standing on the pad and

just starting to run off but I could still see the markings for the

taxiway centerline and taxiway edge.

I had passed most of the line when the AC shuddered. It felt like

the nose gear ran over something. Only when another AC

announced the 777 wingtip contacted the [MD 83] rudder did I know

what happened.

The 777-222 first officer stated that the flight received ATC clearance to enter the 9R hold pad facing north. He observed parked airplanes during the taxi to the 9R hold pad. He, in part, stated:

All observations of parked aircraft positions were beyond my bottom

screw of my aft window (the location of the tip of my right wing

according to my training and flight manual). I informed my captain

that in my opinion, by virtue of my taxi reference points, that I thought

the right wing was clear. ...

As a prior Airbus Captain for United Airlines, based at Chicago

O'Hare, I have limited experience in the 9R hold pad. I have never

seen a configuration of aircraft positioned in the 9R hold pad as I

did that day.

Personnel information

777-222

The captain held an airline transport pilot certificate with an airplane multiengine land rating and held airplane single engine land commercial privileges. He also held a flight engineer certificate. The captain held type ratings in Boeing 737, 757, 767, 777, Airbus A-320, and Cessna 500 airplanes. The operator reported that the captain had accumulated about 15,000 hours of total flight experience, which included 2,048 hours in the Boeing 777. The operator reported that the captain's most recent Federal Aviation Administration (FAA) first class medical certificate was issued on July 6, 2007.

The first officer held an airline transport pilot certificate with a rating for airplane multiengine land. He also held a flight engineer certificate. The first officer held type ratings in Boeing 737, 757, 767, 777, and Airbus A-320 airplanes. The operator reported that the first officer had accumulated about 6,000 hours of total flight experience, which included 92 hours in the Boeing 777. The operator reported that the first officer's most recent FAA first class medical certificate was issued on February 26, 2007.

MD 83

The captain held an airline transport pilot certificate with an airplane multiengine land rating and held airplane single engine land and sea commercial privileges. He also held a flight engineer certificate. The captain held type ratings in Beech 300, 1900, Saab 340, and DC-9 airplanes. He held a certified flight instructors certificate with single engine, multiengine, and instrument airplane ratings. The operator reported that the captain had accumulated about 12,500 hours of total flight experience, which included 7,700 hours in the DC-9 series airplanes. The operator reported that the captain's most recent FAA first class medical certificate was issued on February 13, 2007.

The first officer held an airline transport pilot certificate with a rating for airplane multiengine land and held airplane single engine land commercial privileges. She also held a flight engineer certificate. The first officer held type ratings in Beech 1900 and DC-9 series airplanes. She held a certified flight instructors certificate with single engine, multiengine, and instrument airplane ratings. The operator reported that the first officer had accumulated about 7,610 hours of total flight experience, which included 4,047 hours in the DC-9 series airplanes. The operator reported that the first officer's most recent FAA first class medical certificate was issued on February 16, 2007.

Aircraft information

777-222

The accident airplane, N213UA, a Boeing 777-222, serial number 30219, was a pressurized, low-wing, transport category airplane. The airplane had a full-cantilevered wing and tail surfaces, a semi-monocoque fuselage, and a fully retractable tricycle landing gear. The two wing-mounted Pratt & Whitney 4077 turbofan engines each produced 77,200 lbs of thrust. The airplane was configured to accommodate 348 passengers and 17 crewmembers. The airplane had a