After takeoff, an aircraft slowly gains altitude before reaching a height of 10,000 m and a speed of 900 km/h, just below the speed of sound. Inside the aircraft, an environment similar to that on the ground is artificially created using air conditioners and air pressurization equipment. However, this environment is still significantly different from that on the ground.

• Onboard air pressure and fluctuation
  Onboard air pressure when the aircraft is in level flight is 0.8, which is about the same environment as at 2,000 m above sea level. Since the ratio of oxygen is constant, the amount of oxygen in the air on board is also about 80% of the level on the ground. The change in air pressure occurs on board in the 15 to 30 minutes of ascent after takeoff and descent before landing.
• Temperature
  The onboard temperature is maintained at 24oC using air conditioners.
• Humidity
  The longer the flight, the more the humidity drops. The humidity falls to 20% or less on long flights.
• Vibration
  Vibration occurs during takeoff and landing and when passing through air turbulence.
• Sitting for long periods
  On long-distance international flights, passengers remain seated for long periods of time.