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High-Altitude Operations

High Altitude Equipment​

At an altitude of 18,000 feet, the density of the air has one-half the density of air at sea level.

For flights at and above 24,000 ft. MSL (FL240) where you are using VORs as a primary means of navigation, you must also have a DME or RNAV system installed.*

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* This applies to U.S.-registered civil aircraft within the 50 states and the District of Columbia.

Supplemental Oxygen Requirements​

In an Unpressurized Airplane​

  • At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL):
    • The required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration
  • At cabin pressure altitudes above 14,000 feet (MSL) up to and including 15,000 feet (MSL):
    • The required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes
  • At cabin pressure altitudes above 15,000 feet (MSL):
    • Each occupant of the aircraft is provided with supplemental oxygen
    • Note they passengers are not required to use the oxygen, but it must be provided

In a Pressurized Airplane​

  • No person may operate a civil aircraft of U.S. registry with a pressurized cabin:
    • At flight altitudes above flight level 250: unless at least a 10-minute supply of supplemental oxygen is available for each occupant of the aircraft for use in the event that a descent is necessitated by loss of cabin pressurization
    • At flight altitudes above flight level 350: unless one pilot at the controls of the airplane is wearing and using an oxygen mask that is secured and sealed and that either supplies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude of the airplane exceeds 14,000 feet (MSL), except that the one pilot need not wear and use an oxygen mask while at or below flight level 410 if there are two pilots at the controls and each pilot has a quick-donning type of oxygen mask that can be placed on the face with one hand from the ready position within 5 seconds, supplying oxygen and properly secured and sealed.
  • If for any reason at any time it is necessary for one pilot to leave the controls of the aircraft when operating at flight altitudes above flight level 350, the remaining pilot at the controls shall put on and use an oxygen mask until the other pilot has returned to that crewmember's station.
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