There are four basic conditions requiring the dispensing of oxygen through oxygen masks to aircraft occupants in turbine powered aircraft during flight. The following conditions are derived from the Federal Aviation Regulations (FAR) as listed in Section 2. Condition 1: When the mission of the pressurized aircraft or the operational flight capability is in excess of flight level 300... All cabin occupants must be serviced by an automatic oxygen mask presentation system connected to an operational oxygen source which is activated automatically and/or oxygen flow initiated by the occupant displacing the actuating mechanism when pulling and placing the mask in position on his face in the event of an emergency pressurization failure. An additional 10% of oxygen masks and outlets are to be provided@ uniformly distributed throughout the cabin of the aircraft. Masks@ attached to an operational oxygen source and immediately available (ready position)@ must be provided each flight deck crew member. Observers must have emergency oxygen@ either passenger or crew type. Condition 2: When the mission of the pressurized aircraft or the operational altitude of the aircraft is not in excess of flight level 300@ but above flight level 250... Oxygen masks which are stowed connected to an oxygen supply and can be obtained immediately by each cabin occupant wherever seated when the aircraft is operating above flight level 250@ must be available in the event of an emergency pressurization failure. Demand masks@ connected to an operational source@ must also be immediately available and within easy access of each flight deck crew member. Observers must have emergency oxygen@ either passenger or crew type. Condition 3: When the mission of the pressurized aircraft or the operational altitude of the aircraft is between 10@000 feet and flight level 250... Oxygen masks@ which have been distributed or are stowed and are readily accessible to each cabin occupant when the aircraft is operating above 10@000 feet@ must be available in the event of an emergency pressurization failure. Oxygen masks@ connected to an operational source@ must also be available and within easy access of each flight deck crew member and observer. Condition 4: When the mission of a non-pressurized aircraft is operating above 12@500 feet... Oxygen masks which can be connected to an operational oxygen source must be available and distributable to all occupants of the aircraft during such flight operations. This document defines the accessibility requirements which should be considered in the placement of oxygen masks for presentation to the user and the connections for such oxygen masks to the operational oxygen systems. This is of interest when designing the interior of the aircraft@ placing the seats in relationship to such outlets and mask connections@ or placing oxygen mask outlets in relationship to the seats. Certain Federal Aviation Regulations (FAR's) cover the functional characteristics and requirements of the oxygen systems for aircraft in the mission and operational categories defined above. These should be referred to for the exact functional performance requirements. It is not the intent of this document to insure conformance with these regulations@ but only to recommend general concepts for the location of the oxygen masks and oxygen system outlets for proper accessibility by the aircraft occupants@ whether cabin occupants or crew members. Nor does this document provide any technical information for oxygen system design or function. Please refer to other SAE documents for such information.