Quick Facts
- Type
- Pressurization Parameter
- Definition
- The difference between cabin pressure and outside atmospheric pressure
- Used By
- Pilots, Engineers
Definition#
Differential pressure (delta-P or ΔP) is the difference between the air pressure inside the pressurized cabin and the ambient atmospheric pressure outside the aircraft. At cruise altitude, this differential is typically 7–9 psi.
Why It Matters Operationally#
Differential pressure is the dominant structural load on the fuselage skin during flight. It drives window shape (rounded to distribute stress), fuselage inspection intervals, and fatigue life limits.