AA.I.E.K5

From the FAA library

• 14 CFR Part 121 — Operating Requirements: Domestic, Flag, and Supplemental OperationsOpen
  14 CFR § 121.333 Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes with pressurized cabins.

  required for flight crewmembers on flight deck duty. (c) Use of oxygen masks by flight crewmembers. (1) When operating at flight altitudes above flight level 250, each flight crewmember on flight deck duty must be provided with an oxygen mask ... intercommunication system. When it is not being used at flight altitudes above flight level 250, the oxygen mask must be kept in condition for ready use and located so as to be within the immediate reach of the flight crewmember…

• Pilot's Handbook of Aeronautical Knowledgep. 4-4
  Chapter 4: Principles of Flight › Pressure › Density Altitude

  Density Altitude SDP is a theoretical pressure altitude, but aircraft operate in a nonstandard atmosphere and the term density altitude is used for correlating aerodynamic performance in the nonstandard atmosphere. Density altitude is the vertical distance above sea level ... propeller is less efficient in thin air • Lift because the thin air exerts less force on the airfoils Density altitude is pressure altitude corrected for nonstandard temperature. As the density of the air increases (lower density altitude), aircraft performance increases…

• Pilot's Handbook of Aeronautical Knowledgep. 8-6
  Chapter 8: Flight Instruments › Altimeter Operation

  altimeter indicates an altitude above the actual field elevation. If the barometric pressure setting is reset to the current altimeter setting of 29.68 "Hg, then the field elevation is again indicated on the altimeter. This pressure change ... easily noticed in flight since aircraft fly at specific altitudes. The aircraft steadily decreases true altitude while the altimeter is held constant through pilot action as discussed in the previous section. Knowing the aircraft’s altitude is vitally important…

• Pilot's Handbook of Aeronautical Knowledgep. 8-6
  Chapter 8: Flight Instruments › Types of Altitude

  Indicated altitude—read directly from the altimeter (uncorrected) when it is set to the current altimeter setting. 2. True altitude—the vertical distance of the aircraft above sea level—the actual altitude. It is often expressed as feet above mean ... level (MSL). Airport, terrain, and obstacle elevations on aeronautical charts are true altitudes. 3. Absolute altitude—the vertical distance of an aircraft above the terrain, or above ground level (AGL). 4. Pressure altitude—the altitude indicated when the altimeter setting…

• Pilot's Handbook of Aeronautical Knowledgep. 11-3
  Chapter 11: Aircraft Performance › Density Altitude

  Density Altitude The more appropriate term for correlating aerodynamic performance in the nonstandard atmosphere is density altitude—the altitude in the standard atmosphere corresponding to a particular value of air density. Density altitude is pressure altitude corrected for nonstandard temperature ... density of the air increases (lower density altitude), aircraft performance increases. Conversely, as air density decreases (higher density altitude), aircraft performance decreases. A decrease in air density means a high density altitude; an increase in air density means a lower…

• Aviation Maintenance Technician Handbook - Airframep. G-27
  Glossary

  units of pounds per square inch (psi). Pressure altitude. The altitude in standard air at which the pressure is the same as that of the existing air. Pressure altitude is read on an altimeter when the barometric scale ... Pressure-demand oxygen system. A type of oxygen system used by aircraft that fly at very high altitude. This system functions as a diluter-demand system until, at about 40,000 feet, the output to the mask is pressurized enough…