Definition
An ICAO classification system for instrument approach procedures based on the type of guidance and minima used. ICAO groups instrument approaches into three types: Type A, with a minimum descent height or decision height of 250 feet or more; Type B, with a decision height below 250 feet (further subdivided into Categories I, II, IIIA, IIIB, and IIIC based on visibility and decision height); and a third group covering 3D approach operations using both lateral and vertical guidance, and 2D approach operations using lateral guidance only.
Plain English
ICAO's way of sorting instrument approaches into categories based on how low the pilot can descend before needing to see the runway, and whether the approach gives both side-to-side and up-and-down guidance or only side-to-side.
Context Anchor
Seen in instrument flight rules procedures, approach planning, arrival briefings, and international aviation terminology.
Derivation
Instrument comes from a Latin word meaning a tool or piece of equipment. Approach means to come nearer. Operations refers to actions being carried out. Together, the phrase points to a landing approach carried out with the help of cockpit instruments and a set procedure.
Why Pilots Care
These operations set the weather limits and procedures that determine whether a landing attempt is authorized, directly affecting safety and flight planning decisions.
Grounding Statement
Picture an aircraft descending toward an airport in cloud: the pilot follows the published instrument procedure and cockpit guidance until the runway can be safely seen or the approach must be discontinued.
Intuition Check
Do not read “instrument” here as just any cockpit gauge. In this term, it means the approach is flown using approved navigation guidance and a published procedure. Also, “[ICAO]” does not name a special kind of approach; it shows this is the international wording used by ICAO.
Example Sentence 1
Because the procedure had a decision height of 200 feet, it was classified as a Type B, Category I instrument approach operation under ICAO standards.
Example Sentence 2
ICAO divides instrument approach operations into Type A and Type B categories according to the decision height and runway visual range required.