19960512044299I

Narrative: on 05-12-96, while enroute at 33,000 feet from chicago, IL (mdw) to st. petersburg, FL (pie), American trans air flight #406, a Boeing 727-290, N775AT, experienced a loss of pressurization. An emergency descent was executed. The aircraft diverted to, and landed at Indianapolis, IN (ind). Prior to the loss of pressurization, the aircraft's cabin altitude warning horn sounded. The rise in cabin altitude which caused this warning horn to sound occurred because the flight engineer failed to notice that the right pack switch was in the off position. The captain observed that the right pack switch was off. He directed the flight engineer to place that switch in the on position. After doing so, the flight engineer attempted to regain control of the cabin's pressure. In this attempt, he failed to close the cargo heat outflow valve. In addition, he selected man(ual) ac on the electronic pressurization controller and toggled the pressurization outflow valve to the open position. This caused a rapid loss of cabin pressure which necessitated the emergency descent. Immediately after the loss of cabin pressure, both the flight engineer and the first officer, who was flying the aircraft, donned their oxygen masks. Rather than donning his oxygen mask immediately, the captain asked the lead flight attendant, who happened to be on the flight deck, to check and see if the passenger oxygen masks had deployed. After she reported that they had, the captain attempted to don his oxygen mask. That attempt was unsuccessful. He became hypoxic and lost consciousness. The flight attendant became hypoxic and loss consciousness at the rear of the flight deck. The flight engineer left his duty position and placed the second observer's oxygen mask on the flight attendant, who then regained consciousness. While this was occurring, the first officer initiated the emergency descent. After regaining consciousness, the flight attendant noticed that the captain was slumped over, his oxygen mask out of place. She went to the captain's assistance and placed his oxygen mask on his face. The flight attendant then noticed that the flight engineer was slumped over, unconscious, with his oxygen mask out of place. The flight attendant went to the flight engineer's assistance and placed his oxygen mask on his face. He regained consciousness. It is not known how the flight engineer's oxygen mask became dislodged. After regaining consciousness, the captain took over control of the aircraft. He diverted flight #406 to Indianapolis where a landing was made without further incident.