Sequence of Events
The captain received permission from the ramp tower to commence a power-back and signaled to the marshaller that clearance was obtained. As the aircraft lined up parallel to the north-south taxi line during the maneuver, the captain felt a loud thump on the left side. A baggage tug was observed moving behind the aircraft during the power-back turn. The marshaller saw the tug driver get jet blasted and one of the baggage carts lying on the ground.
The left wing walker noticed the tug driver come to a complete stop in the neutral area. The wing walker motioned for the tug driver to cross behind the aircraft before the marshaller initiated the power-back. The tug driver pointed at the tug as if indicating a problem, and shortly after, the aircraft collided with a baggage cart.
The tug driver reported seeing the wing walker clear the tug to pass behind the aircraft. As the tug driver proceeded slowly, the trailing edge of the aircraft's wing approached. The tug driver attempted to speed up to avoid contact, but the wingtip struck the fourth cart, knocking it off the transporter.
Damage
Examination of the left wing revealed that the trailing edge of the aileron and the wingtip were buckled.
Applicable Procedures
The Airtran Standard Practice Flight Crew Powerback procedures, General Guidelines 6719.3, Part (D), state: "It is the responsibility of the ground crew to ensure that the ramp area is clear of foreign objects and conflicting traffic before and during powerback."