Definition
A fluid-based system fitted to some piston and turbine aircraft that automatically delivers a chemical agent to engine and airframe surfaces to remove ice that has formed and to inhibit further ice formation during flight in icing conditions.
Plain English
A built-in system that automatically sprays an anti-ice fluid where ice could form, both melting any ice already there and stopping more from building up.
Context Anchor
You may see ADI in airport information, maintenance notes, or NOTAM-style text describing winter operations or ice-control equipment.
Derivation
‘De-ice’ means to remove ice already formed; ‘inhibitor’ comes from the Latin ‘inhibere’ meaning ‘to hold back’ — here, holding back the formation of new ice. Together the term describes a system that does both jobs at once: removes existing ice and prevents new ice from forming.
Why Pilots Care
Maintains clean aerodynamic surfaces without requiring constant pilot attention during flight in icing conditions.
Intuition Check
Do not read “inhibitor” as something that removes ice by itself. In this term, de-ice is the removal part; inhibitor is the part that helps delay new ice from forming.
Example Sentence 1
Before entering the cloud layer, the pilot armed the ADI system to keep ice from accumulating on the wings and propeller.
Example Sentence 2
During the preflight inspection the crew checked that the ADI fluid reservoir was full.