Incident Overview
On August 4, 2015, at approximately 1800 mountain daylight time, a Boeing 737-700 airplane, registration N779SW, collided with a provisioning truck while maneuvering at Denver International Airport (DEN), Denver, Colorado. The airplane was operated by Southwest Airlines under 14 Code of Federal Regulations Part 121 as a scheduled domestic passenger flight. Visual meteorological conditions prevailed before and during the ground operations. The flight was originating at the time of the collision.
Sequence of Events
The airplane was parked at Gate C28. Video footage provided by Southwest Airlines captured the events. At 05:57:44 PM, the luggage belt pulled away from the airplane's right front side. By 05:58:15, the jet bridge began to retract. The gate lead started a walk-around at 05:58:36, moved a safety cone from under the left wing at 05:59:02, and became visible under the empennage at 05:59:29. At 06:00:28, the gate lead boarded the airplane tug, and a wing walker moved toward the right wing tip. At 06:00:53, another Southwest Airlines airplane scheduled for Gate 26 arrived and began turning toward its gate. At 06:01:02, the tug driver started pushing the Gate 28 airplane back as the Gate 26 airplane continued to pull in. The collision began at 06:01:17 and ended at 06:01:24 when both vehicles stopped.
Damage and Injuries
The outboard trailing edge of the left wing struck the fiberglass box on the passenger side of the provisioning truck. The truck rolled and came to rest on its driver's side. The airplane sustained minor impact damage to the skin, measuring 2 inches by 18 inches. No injuries were reported among the flight crew or passengers. The driver of the provisioning truck sustained minor injuries and egressed without further incident.
Personnel Interviews
During an interview, the lead agent/tug driver for Gate 28 stated this was his first pushback of the day. He performed a walk-around but did not recall seeing the provisioning truck inside the safety area. After receiving clearance from both the wing walker and the pilot, he began pushing back. He stopped when he felt the tug or jerk from the collision. He noted his headset had issues and reported feeling stressed and potentially distracted by personal issues.
The guide agent stated he saw the provisioning truck but was unsure whether it was in the safety area for Gate 28. He assumed it was clear because the lead agent had walked past it during the walk-around and announced its completion. He was on the opposite side of the airplane during pushback and commented that a second wing walker would have prevented the incident.
The provisions agent reported parking outside the safety area for Gate 26 but later acknowledged he was likely within the safety area for Gate 28. He was awaiting an inbound airplane to service at Gate 26. He stated he had never been instructed to remain clear of safety areas for adjacent gates, only to move his truck if asked. He did not receive such a request from the Gate 28 ground crew.
Manuals and Procedures
The Ground Operations Manual (Section 5.19.2 Pushback Procedures and Radio Communications) and the Prepush Checklist (WN-1095, REV. 11/12) include an observation for the pushback driver to ensure the safety zone is clear of foreign objects, personnel, and equipment. The Provisioning Manual (Safety Section 10.5 Driving and Ramp Safety, paragraph 2.6.7 Parking of Provisioning Vehicles Between Safety Zones) states that employees holding short at a gate for incoming aircraft should always ensure they are outside the safety zone and should be aware of incoming flights at adjacent gates and flights pushing back from adjacent gates.