NTSB Factual Report

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 maximum gross takeoff weight of 499,800 lbs.

The airplane was being maintained by compliance with a FAA approved continuous airworthiness program. The airplane's last inspection was completed on June 15, 2007. According to the operator, the airplane had accumulated 24,202 hours total time in service at that inspection.

According to a manufacturer's drawing, the general dimensions for the airplane was a 199 foot, 11 inch wing span and a 209 foot, 1 inch overall length.

MD 83

The accident airplane, N9630A, a McDonnell Douglas MD 83, serial number 53561, was a pressurized, low-wing, transport category airplane. The MD 83 had fully cantilevered wings, a T-tail empennage, and was powered by two Pratt & Whitney JT8D-217A engines, each producing 20,000 lbs of thrust. The accident airplane was configured to accommodate a maximum of 136 passengers and 8 crewmembers. The airplane had a certified maximum takeoff weight of 150,000 lbs.

The accident airplane was maintained by compliance with a FAA approved continuous airworthiness program and accumulated a total time of 29,751 hours at the time of the accident. The airplane's last inspection was completed on October 26, 2006.

According to an operator's specification, the general dimensions for the airplane was a 107 foot, 10 inch wing span and a 147 foot, 10 inch overall length. Its T-tail empennage had a 29 foot, 5 inch height.

METEOROLOGICAL INFORMATION

At 1551, the ORD weather was: Wind 280 degrees at 14 knots gusting to 19 knots; visibility 10 statute miles; sky condition scattered 25,000; temperature 23 degrees C; dew point 4 degrees C; altimeter 30.06 inches of mercury.

AIRPORT INFORMATION

ORD was located approximately 14 miles northwest of Chicago, Illinois, and was owned and operated by the city of Chicago, Illinois. ORD was a certificated airport under 14 CFR Part 139. ORD 's field elevation was 668 feet above mean sea level (MSL). ORD had 6 runways: Runway 14R/32L - 13,000 feet by 200 feet, asphalt/concrete/grooved; runway 9R/27L - 10,144 feet by 150 feet, asphalt/concrete/grooved; runway 14L/32R - 10,005 feet by 150 feet, asphalt/concrete/grooved; runway 4R/22L - 8,075 feet by 150 feet, asphalt/grooved; runway 9L/27R - 7,967 feet by 150 feet, asphalt/concrete/grooved; and runway 4L/22R - 7,500 feet by 150 feet, asphalt/grooved.

The 9R hold pad is located north of the west end of taxiway M. The marked pad was about 1,700 feet by about 400 feet. According to a chart supplied by the airport certificate holder, the pad's delineation line along taxiway M was 224 feet north of its centerline and 186 feet north of its north taxiway edge marking. Information current at the time of the accident, provided by UAL, and published in a Jeppesen chart, titled "HOLD PADS", in part stated:

Pilots exercise caution taxiing past hold pad with parked aircraft -

maintain centerline.

Entire aircraft must be contained inside pad boundary line/lights.

Pilots should maximize the pad space when positioning [aircraft].

There are no positioning lines except for de-icing operations.

...

RWY 9R HOLD PAD

The eastern most position is authorized for B767-300 or smaller, all

other positions are authorized up to B747-400.

All aircraft must face nose south.

Six (6) green lines are used only during secondary de-icing.

A FAA 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.

WRECKAGE AND IMPACT INFORMATION

NTSB, FAA inspectors, and representatives of the operators examined the airplanes after the accident. The upper section of the rudder on the MD 83's T-tail was torn in a right to left direction as viewed from the aft facing forward. The tearing was consistent with a westbound impact of a north-facing airplane. The 777-222's right navigation light assembly, leading edge slat, and right wing mid and aft tip assembly were damaged.

The hold pad area was examined. The pad's and taxiway M's markings were reviewed and no anomalies were observed. Wreckage debris to include green media consistent with a right wing navigation light was found on the hold pad. The debris was found about 90 feet north of taxiway M's centerline and about 52 feet north of taxiway M's edge line. The debris was found outside of the 9R hold pad about 135 feet south of its delineation line.

ATC radio transmission tapes were reviewed. The tapes indicated that air traffic controllers directed the airplanes to include the accident MD 83 on the 9R hold pad into their standing positions during the ground stop.

ADDITIONAL DATA/INFORMATION

The MD 83's T-tail is not observable from the pilot's seats in the cockpit.

Subsequent to the accident the 9R hold pad was renamed the 10R hold pad and was redesigned. The area encircling the hold pad was marked as taxiway. Taxiway M borders the south area of the 10R hold pad and taxiway Kilo (K) borders the north area of the 10R hold pad.

NTSB Probable Cause

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.