Definition
Aircraft classifications used in instrument approach procedures, based on the aircraft's approach speed (1.3 times the stall speed in landing configuration at maximum certificated landing weight, known as VREF). Category A includes aircraft with an approach speed of less than 91 knots. Category B includes aircraft with an approach speed of 91 knots or more but less than 121 knots. The category determines which minimums and circling protected areas apply on an instrument approach chart.
Plain English
Slower aircraft are sorted into groups based on how fast they fly final approach. Category A is the slowest group (under 91 knots), and Category B is the next step up (91 to under 121 knots). Most light single-engine and many light twin trainers fall into these two groups. The group your aircraft falls into tells you which set of approach minimums to use.
Context Anchor
You see this term in instrument procedure discussions, especially where protected airspace, minimums, holding, course reversals, or entry procedures depend on aircraft speed.
Derivation
Category comes from a Greek word meaning a class or grouping. In aviation, it helps to think of these as speed groups, not as makes or models of aircraft.
Why Pilots Care
Determines the size of the protected airspace and the applicable minimum altitudes or visibility requirements.
Intuition Check
Do not read “category” here as a broad aircraft type, like airplane, helicopter, single-engine, or multi-engine. Here it means a specific FAA speed group based on how fast the aircraft approaches to land.
Example Sentence 1
Flying a Cessna 172 with an approach speed around 65 knots, the pilot used the Category A minimums on the ILS chart.
Example Sentence 2
Category B minimums were used on the approach plate since the aircraft's speed placed it in that group.