Although airplanes fly at high altitudes with thin air, they are generally safe for most COPD patients to fly in because they are confined spaces. However, for patients with chronic respiratory failure, oxygen is required during the flight, and the oxygen flow rate should be increased by 1 to 2L/min. Patients with chronic obstructive pulmonary disease (COPD) who normally have an arterial partial pressure of 70 mmHg without oxygen are safe to fly without increased oxygen supply, but this does not exclude the possibility of severe hypoxemia during the flight. It is important to note that COPD patients should make some preparations before flying, such as bringing their usual medications and aerosols for quick relief of symptoms, and checking carefully for other factors that may cause hypoxemia, such as anemia and cardiac insufficiency. During the flight, COPD patients walking back and forth in the cabin can also aggravate hypoxemia.