Definition
Hot, high-pressure air drawn (bled) from the compressor section of a turbine engine and routed through ducting to power or supply other aircraft systems, such as anti-icing of wing leading edges and engine inlets, cabin pressurization and heating, and pneumatic instrument or actuation systems.
Plain English
Hot air taken from inside a running jet engine and piped to other parts of the aircraft to do useful work, like keeping ice off the wings or warming the cabin.
Context Anchor
Seen in turbine aircraft system descriptions, especially anti-icing and deicing systems that use engine heat to protect inlets, wings, or tail surfaces from ice.
Derivation
From the verb 'bleed,' meaning to draw off a small amount of fluid or gas from a larger supply. The engine's compressor produces far more compressed air than it needs for combustion, so a portion is 'bled off' through ports for other uses.
Why Pilots Care
Allows safe flight in icing conditions by preventing ice on critical surfaces and supplies essential cabin systems.
Intuition Check
Bleed air does not mean air leaking out by accident. In aviation use, it is air intentionally taken from the engine and sent to an aircraft system.
Example Sentence 1
Before entering icing conditions, the crew turned on the wing anti-ice system, which uses bleed air from the engines to heat the leading edges.
Example Sentence 2
Bleed air from both engines feeds the cabin pressurization system during climb.