Incident Overview
An All Nippon Airways (ANA) Boeing 777-281 and a United Airlines (UAL) Boeing 777-22B collided on the ground, resulting in substantial damage to both aircraft. The collision involved the right wing tips of both airplanes and occurred in the nonmovement area ramp surrounding the G terminal.
Sequence of Events
The ramp area is under the control of a local ground control tower operated by United Airlines. At the time of the collision, both aircraft were under the direction of this ramp control tower. The transfer point for ground control responsibility between the ramp control tower and the Federal Aviation Administration Air Traffic Control Tower is designated as Spot 10, where the G-ramp intersects taxiway A. Gate G-102, the terminal gate closest to Spot 10, is located along the southern boundary of taxiway A.
The ANA 777 had received clearance from the ramp control tower to taxi to Spot 10 and was proceeding outbound past gate G-102. The UAL 777 had been cleared by the ramp control tower to push back from gate G-102.
Actions Prior to Collision
According to recorded radio communications, the ramp controller did not issue a cautionary advisory to either flight crew regarding the movement of the other aircraft. The pushback tractor driver for the UAL 777 observed the approaching ANA 777 and halted the pushback just moments before the collision. The flight crew of the ANA 777 saw the UAL 777 and made a slight left maneuver away from the other aircraft in an attempt to ensure wing tip clearance immediately before contact. The pilots on the ANA 777 could not visually see the aircraft's wingtips from the cockpit. The UAL 777's wing walker was positioned on the left side of the aircraft to block traffic and noticed the ANA 777's approach and the collision shortly after the pushback was stopped.