You are right, I am wrong about this one (my Jepp paper copy is way too old)
"The Airport Reference Code (ARC) is a coding system developed by the Federal Aviation Administration to relate airport design criteria to the operational and physical characteristics of the airplane types that will operate at a particular airport. (The ARC is part of design standards established in the FAA Advisory Circular 150/5300-13,
Airport Design</I>, June 2008.) The ARC has two components relating to the airport design aircraft. The first component, depicted by a letter, is the "approach category" and is based on aircraft approach speed. The second component, depicted by a Roman numeral, is the airplane "design group" and is based on airplane wingspan."
But you are wrong about how the CAT is established (FAR 97):
(b)
Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3 VS0
at the maximum certificated landing weight. VREF, VS0, and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry. The categories are as follows:
(1) Category A: Speed less than 91 knots.
(2) Category B: Speed 91 knots or more but less than 121 knots.
(3) Category C: Speed 121 knots or more but less than 141 knots.
(4) Category D: Speed 141 knots or more but less than 166 knots.
(5) Category E: Speed 166 knots or more.
or ICAO:
While the speed ranges used to determine an aircraft's approach category are identical to 14 CFR 97.3 (
ICAO Doc 8168 PANS-OPS Vol 1, Section 4, Paragraph 1.3.5), the maximum permitted speed for visual maneuvering is significantly higher.
The method used for determining the approach category speed is slightly different: VAT = speed at threshold based on 1.3 times
VS0 or 1.23 times
Vs1g at maximum certificated weight. Additionally, speed ranges are specified for other segments of the approach: (ICAO Doc 8168, Vol 1, Section 4, Table I-4-1-2).
In both cases, CAT is at MLW and there is only one per aircraft(we agree on that!).