At flight level 450, the cabin altitude is approximately how many feet?

• A. 3000
• B. 6000
• C. 9000
• D. 12000

Answer: (B)

When an airplane climbs to high cruising altitudes, the cabin is pressurized to a lower altitude than outside so people can breathe comfortably and the aircraft structure isn’t stressed by a huge pressure difference. The pressurization system targets a cabin altitude that feels like flying at a modest height, even though the plane is at 45,000 feet.

At FL450, the outside air is extremely thin, so the cabin is typically kept around 6,000 feet. This provides sufficient oxygen and comfort for passengers and crew while staying within the aircraft’s design limits. So the approximate cabin altitude is about 6,000 feet.