On June 8, 2006, about 1700 eastern daylight time, a Boeing 737-300, N403TZ, operated by American Trans Air, Inc., and piloted by an airline transport pilot, sustained substantial damage when a foreign object struck the tail of the airplane during taxi for takeoff at the LaGuardia Airport, New York, New York . The 14 CFR Part 121 flight was operating in visual meteorological conditions and was on an instrument flight rules flight plan. There were no injuries to the 5 crewmembers or 138 passengers on board the airplane. The flight was originating at the time of the accident and the intended destination was the Chicago Midway International Airport, Chicago, Illinois. According to a report from the airplane's operator, a piece of steel plate measuring about 25 inches by 60 inches struck the right horizontal stabilizer of the airplane while it was taxiing for takeoff on taxiway B. Investigation revealed that the plate had been left on the taxiway by workers for a company performing maintenance on the taxiway. The plate was used to cover the area on the taxiway that was receiving maintenance. According to the FAA representative, the plate was an aluminum diamond plate material, not steel. The plate was supposed to have been a thicker and hence heavier steel plate to prevent it from being affected by the jet blast from taxiing airplanes. Guidance to the construction company regarding the use of such plates was provided by the FAA and the airport authority.