HISTORY OF FLIGHT On August 5, 2001, about 1740 eastern daylight time (EDT), a US Airways Express/Piedmont employee was fatally struck by the right propeller blades of a US Airways de Havilland Dash 8, N935HA, operating as flight 3340. The airplane was taxiing for departure from Washington Ronald Reagan National Airport (DCA) for White Plains, New York. It was the employee's first day working at DCA and his first day back at work from extended leave. The accident occurred at US Airways Express operations ramp pad F, located north of passenger gate 35A in the north pier of terminal C. The ramp surface was concrete and asphalt. According to the Metropolitan Washington Airports Authority report, "at the time of the accident the ramp was dry, free of debris and showed spots of dried oil and fuel deposits." RAMP AGENT ACTIONS US Airways records indicated that the ramp agent reported to work at 0835 EDT. Another US Airways employee who worked with the ramp agent in the morning and saw him throughout the day said the ramp agent was in good spirits and appeared normal. About 1540 EDT, the ramp agent complained of a headache and received two Advil tablets and a soft drink from the flight attendant of a delayed US Airways airplane, N986HA. The airplane, which was located at ramp pad A, had been delayed by a mechanical problem. The ramp agent rested inside the cabin of this airplane until about 1600 EDT to escape the heat. The flight attendant of N986HA reported that the ramp agent looked tired while on board the airplane. About a half hour later, the captain of N986HA saw the ramp agent lying in the baggage compartment of the airplane with his legs hanging out the door. The captain spoke to the ramp agent but did not receive a response and thought he was napping. About 2 hours after the ramp agent had complained of a headache, US Airways Express flight 3340, containing 3 crew members and 32 passengers, was parked with its engines idling while the ramp agent and a marshaller prepared the area immediately around the airplane for departure. The ramp agent removed the nose landing gear chocks and tossed them to the right side of the airplane. The captain signaled that he was ready to taxi, the marshaller signaled a go-ahead, and the airplane began to move forward. Both the marshaller and the ramp agent were in front of the accident airplane when they noticed that the chocks had landed in the path of the right main landing gear. The marshaller signaled the captain to stop the airplane, but before the captain could shut the engines down, the ramp agent attempted to remove the chocks. As the ramp agent approached the chocks, the marshaller and a coworker yelled at him to stop, but he did not stop and was fatally struck by the right engine's propellers. PERSONNEL INFORMATION Prior to the accident, the ramp agent had worked for US Airways Express at Washington Dulles International Airport (IAD) since September 2000. He worked part time, 2 days a week, around propeller-driven airplanes. His training records indicate that he had satisfactorily completed all initial and recurrent training and was also qualified to marshal airplanes. The ramp agent had received two commendations and had no disciplinary actions on his record. His coworkers described him as very safety conscious and a hard worker. They also described his actions on the day of the accident as out of the ordinary for him. In the summer of 2001, US Airways Express had transferred its operations from IAD to DCA. During the period of transition, US Airways granted its employees 30 days of leave, which the ramp agent had just completed when he returned to work on the day of the accident. METEOROLOGICAL INFORMATION The weather at DCA at the time of the accident was reported as follows: winds, 190 degrees at 9 knots; visibility, 5 miles with haze; temperature, 84 degrees F; relative humidity, 70 percent; and heat index, 91 degrees F. All witnesses described the weather as very hot. MEDICAL INFORMATION The ramp agent's wife stated that he had a medical problem involving his thyroid. His medical records indicated that, approximately 8 months before the accident, an endocrinologist had diagnosed him with Graves' hyperthyroidism. Hyperthyroidism is known to cause anxiety, insomnia, muscle weakness, elevated heart rate, abnormal heart rhythms, weight loss, and heat intolerance. [See, for example, "Diseases of the Thyroid" in Harrison's Priniciples of Internal Medicine (McGraw Hill, Inc.).] Impaired mental functioning is common, including a decreased ability to concentrate, decreased memory, and decreased attention span. [See, for example, "Graves' Disease" in Endocrinology (W.B. Saunders Company) and "Metabolic, Physiologic, and Clinical Indexes of Thyroid Function" in Werner and Inbar's The Thyroid: a Fundamental and Clinical Text, 8th Edition (Lippincott, Williams & Wilkins).] The endocrinologist prescribed methimazole and propranolol to control symptoms of the disease. However, medical records indicate that the ramp agent's thyroid hormone levels, last measured approximately 1 month before the accident, remained markedly elevated. Approximately 10 days before the accident, the ramp agent was also prescribed a low dose of alprazolam for anxiety and was given a note to return to work with no contraindication to regular work activities. In addition to the common side effects of drowsiness and light-headedness, alprazolam has been shown to impair performance of many cognitive and psychomotor tasks. Toxicological testing performed by the Federal Aviation Administration (FAA) Civil Aeromedical Institute Toxicology Laboratory for the ramp agent detected propranolol. Alprazolam was not reported on the FAA toxicology evaluation, but the laboratory threshold for reporting is above the normal therapeutic levels for this medication.