CHI01LA331

The airplane rolled forward when it was disconnected from its tow, pinning and seriously injuring a wing walker. Hand signals were being used rather than headphones during the night push back. The wing walker stated that the hand signal to set brakes was given to the captain who in turn returned the set brakes hand signal. According to the captain, the last hand signal that he saw was to start engines. After starting the number one engine, the first officer felt the airplane move forward. The first officer stated that he asked the captain if the parking brake was supposed to be set at which time the captain looked down and set it. The tug driver signaled a problem and the engine was shut down. The airplane's Before Start Checklist stipulates the setting of the parking brake before engine start.

On September 23, 2001, at 1930 central daylight time, a Boeing 757-222, N570UA, operated by United Airlines (UAL) as flight 153, struck and seriously injured a wing walker during push back from gate C-3 at the Indianapolis International Airport (IND), Indianapolis, Indiana. The accident occurred when the airplane rolled forward on the wing walker's leg pinning her leg under the nose wheel following disconnection of the tow bar. Night visual meteorological conditions prevailed at the time of the accident. No other injuries were reported. The scheduled domestic passenger flight was operating on an instrument flight rules flight plan under the provisions of Title 14 CFR Part 121. The flight was scheduled to depart IND at 1915 with a destination of Chicago, Illinois.

The injured wing walker reported, "...I was wearing a radio and advised the gate agent ... to advise the captain we would be using hand signals. [The gate agent] confirmed to me that was fine with the captain. We started to push back from gate C3 and proceeded into the alley way. [The push back driver] came to a stop and he gave me the set brakes signal. I made eye contact with the captain and I lifted my hands above my head and gave the captain the set brakes hand signal (open hand to closed fist). He returned the same signal. I gave him the thumbs up acknowledgement. I then walked to the tow bar to begin the disconnect. I moved to release the handle on the tow bar and the plane began to roll on me knocking me to the ground."

The tractor driver reported, "On Sep 23 Sunday me and [the wing walker] were ready to push 153 (757). I was in the push back [the wing walker] was wing walking. I had no headset so we use hand signals to release brakes. I push the 757 like I always do, had the a/c inline w/ the alley. Once I was set w/ the airplane I signal[ed] [the wing walker] to tell the pilot to set brakes. From what I saw [the wing walker] gave him the signal to set brakes then she signal[ed] to me that the pilot had set brakes. [The wing walker] proceed[ed] to release the 757 tow bar, when she released the bar the 757 started to roll forward. From what I saw [the wing walker] looked like she was trying to stop the a/c. I immediately put the pushback in reverse [as soon as possible]. Once I was clear of [the wing walker] and the a/c I got out off the pushback and ran to [the wing walker]. Once I realized how much trouble she was in, I ran to go get help."

The captain reported, "Flight two hours late out of IND, pushback with no headphone. Last hand signal seen to start engines, CSR that was directing pushback went under nose. Felt aircraft moving forward and put on parking brake. Tug driver signal a problem, shut down engine. Evidently CSR's leg stuck under nose gear. Coordinated with ground to push aircraft back. CSR taken to hospital. No fracture. Problem would have been avoided with working headset better training of out of station personnel on hand signals..."

The first officer reported "We were scheduled for a 1710 departure from Indianapolis to Chicago but were delayed approximately two hours and ten minutes due to lightning in the airport area (the last flight's baggage could not be unloaded, or our baggage loaded)".

"Pushback would be via hand signals for reasons not explained at the time. Initial pushback was uneventful. I had sight of the tow tractor to the right, but never caught sight of the taxi director to the left until after the incident (when she was finally extricated)".

"[The captain] relayed to me that he had been given the signal to start engines, and I commenced the start sequence for engine number one. After rollback on engine number one I initiated start on engine number two but had not yet introduced fuel when I felt the aircraft move very slightly forward. Due to the geometry of the pushback all I could see out my windows was the tow tractor cocked at an angle to the tow bar to my right. I asked [the captain] if the parking brake was supposed to be set. He looked down and set it".

"Very shortly thereafter the tractor driver exited the cab frantically and it was immediately apparent that something was wrong. I secured the left engine and opened the window, simultaneously telling [the captain] that something was going on, evidently at the nose gear".

"We never had voice communications with the ground crew (other than my yelling out the window after the incident) until the female Customer Service Representative who had been directing us was freed and taken to the hospital. Correspondingly, the only command I heard from [the captain] regarding pushback was to start engines".

"We followed ground directions via hand signals and yelling back and forth through my open window to coordinate brake release to enable the tug to push us back and free the Customer Service Representative’s leg. After she was freed we requested to be towed back to the gate (after coordination with Dispatch and the Operations Duty Flight Manager), but the tug sheared a tow bar pin during the attempt. We started the left engine, taxied back to the gate, and deplaned without further incident".

The UAL Maintenance Manual states under "No Verbal Communications Dispatching" paragraph B, states, "Starting of any engines must be done at the gate before pushback or after the final pushback 'Brakes set' signal. When starting less than all engines at the gate, the pilot is expected to use the normal sequence for the condition (APU/Ground Pneumatics), then signal for power disconnect when the desired number of engines are running."

The UAL 757 Before Start Checklist includes the parking brake as checklist item, which is to be challenged by the first officer with a response provided by the captain. The item is as follows:

Parking brake ........................................................ Set, pressure normal (C)

The Federal Aviation Administration and UAL were parties to the investigation.