What is the normal pressure range during air transport?

• A. 50 kPa to 100 kPa
• B. 25 kPa to 75 kPa
• C. 10 kPa to 20 kPa
• D. 5 kPa to 25 kPa

Answer: (B)

The key idea is that air travel involves two pressures: the low external air pressure at cruising altitude and the higher, maintained cabin pressure. At cruise, outside atmospheric pressure is roughly 20–30 kPa, while the cabin is pressurized to about 75–80 kPa to keep passengers comfortable. Taken together, the pressure range experienced in flight—from the outside environment up to the cabin—is about 25–75 kPa. This is why the option spanning roughly 25–75 kPa fits best. The other ranges either miss the typical outside-ambient value or the cabin-pressure value.