Definition
The passage in a turbine engine installation that guides outside air from the intake opening into the face of the compressor. It is shaped to deliver air to the compressor at the correct velocity, pressure, and flow direction across the engine's operating range.
Plain English
The shaped tube or channel that carries air from the outside of the aircraft into the front of a jet or turbine engine.
Context Anchor
Seen during engine preflight inspections, aircraft maintenance, and discussions of engine air intake systems.
Derivation
Inlet means an opening where something enters. Duct comes from the Latin ducere, meaning to lead or guide. Together: a guided entry path — in this case, for air entering the engine.
Why Pilots Care
A damaged or poorly designed inlet duct can cause compressor stall, reduced engine power, or engine damage from ingested debris.
Intuition Check
Do not think of the inlet duct as only the outside opening. In aviation use, it is the whole shaped passage that carries air from the opening toward the engine.
Example Sentence 1
During the preflight walkaround, the pilot inspected the inlet duct for any foreign objects or signs of damage.
Example Sentence 2
At high speed the inlet duct slows incoming air before it reaches the compressor blades.