sentences:  About one hour after refueling, while the aircraft was circling above its designated area, Captain Haug directed co-pilot Svitenko to take his rest period.His seat was taken by the spare pilot, D'Mario.The crew was uncomfortable because of the cold, although the heater's rheostat was turned up, so D'Mario opened an engine bleed valve to draw additional hot air into the heater from the engine manifold.