FAA Standards · Runway Design

Understanding Your Airport’s Runway Design Code (RDC)

By AvPlot Team Published June 2026 8 min read

Almost every dimensional standard in AC 150/5300-13B, Airport Design — safety areas, object free areas, protection zones, separations — is keyed to a single three-part code. The Runway Design Code (RDC) is that key. Get it right and the rest of the design follows; get it wrong, and every downstream dimension inherits the error. This is how the RDC is built, component by component, and how you determine yours from the critical aircraft.

What the RDC is

The Runway Design Code is a three-part code that signals the design intent of a runway. It is the entry key into nearly every dimensional design standard in the AC: change the RDC and you change the runway’s entire dimensional footprint. The format is AAC–ADG–visibility — for example, C-III-2400. Read left to right, that says: Aircraft Approach Category C, Airplane Design Group III, lowest planned visibility minimum of 2,400 ft RVR.

Source: AC 150/5300-13B Change 1, §3.2 (Runway Design Code), with component definitions in §1.6 and Tables 1-1 and 1-2.

RDC vs. RRC — design intent vs. current capability

The RDC is easy to confuse with the closely related Runway Reference Code (RRC). The distinction matters: the RDC reflects design intent — what the runway is being designed to — while the RRC reflects current operational capability — what the runway supports today. The two are identical on most existing runways, but they diverge whenever a runway is being designed for future, more demanding aircraft. A runway operating today at B-II but designed to accommodate a forecast C-III fleet carries an RRC of B-II and an RDC of C-III. Design always builds to the RDC.

Component 1 — Aircraft Approach Category (AAC)

The first component is a letter describing approach speed. The AAC is based on 1.3 times the stall speed in landing configuration (V_REF) for the aircraft at its maximum certificated landing weight. Faster approach speeds demand longer, wider safety margins, so the category drives several runway dimensions directly.

Table 1-1 — Aircraft Approach Category by approach speed
AAC	Approach speed
A	< 91 kt
B	91–120 kt
C	121–140 kt
D	141–165 kt
E	≥ 166 kt

Source: AC 150/5300-13B Chg 1, §1.6, Table 1-1.

Component 2 — Airplane Design Group (ADG)

The second component is a Roman numeral describing the aircraft’s physical size. The ADG is governed by the more demanding of two measurements: wingspan and tail height. If an aircraft’s wingspan places it in Group III but its tail height places it in Group IV, the aircraft is Group IV — the more demanding measurement always wins. The wingspan boundaries are below.

Table 1-2 — Airplane Design Group by wingspan
ADG	Wingspan
I	< 49 ft
II	49–79 ft
III	79–118 ft
IV	118–171 ft
V	171–214 ft
VI	≥ 214 ft

Source: AC 150/5300-13B Chg 1, §1.6, Table 1-2. Tail-height boundaries appear in the same table; the more demanding of wingspan or tail height governs.

Component 3 — Visibility minimums

The third component is the visibility minimum for the lowest approach planned to the runway, expressed as the runway visual range (RVR) in feet. The standard values are:

VIS — visual, no instrument approach planned
5000 — not lower than 1 statute mile (≈ 5,000 ft RVR)
4000 — not lower than 3/4 statute mile (≈ 4,000 ft RVR)
2400 — not lower than 1/2 statute mile (≈ 2,400 ft RVR)
1600 — not lower than 1/4 statute mile (≈ 1,600 ft RVR)
1200 — the lowest standard RVR tier

The rule of thumb: lower RVR means more demanding standards. A tighter visibility minimum widens or extends several dimensions — some Runway Safety Area and Runway Object Free Area rows grow, the Runway Protection Zone gets larger, and approach-surface clearances tighten. The visibility component is where the runway’s instrument capability flows into its geometry.

How to determine your RDC

Building the RDC is a five-step process, and it begins not with the runway but with the aircraft that drives it.

Step 1 — Identify the critical aircraft

The critical aircraft (also called the design aircraft or critical design aircraft) is the most demanding aircraft, or family of aircraft, that makes — or is forecast to make — substantial use of the runway. “Substantial use” is generally 500 or more annual operations, counting itinerant operations and treating touch-and-go operations appropriately. The critical aircraft can be a single type or a cumulative grouping of aircraft with similar characteristics. Everything downstream depends on getting this right.

Source: AC 150/5300-13B Chg 1, §2.6.1 (critical aircraft). AvPlot’s forecast tooling applies the AC 150/5000-17 critical-aircraft methodology to identify the design aircraft from activity data.

Step 2 — Determine the AAC

Take the critical aircraft’s approach speed (1.3 × V_SO, i.e. V_REF) and read it against Table 1-1. That letter — A through E — is the first character of the RDC.

Step 3 — Determine the ADG

Take the critical aircraft’s wingspan and tail height and read each against Table 1-2. The more demanding of the two governs the Roman numeral — the second character of the RDC.

Step 4 — Determine the visibility component

Identify the lowest approach visibility minimum the runway is planned to support and convert it to its RVR value (VIS, 5000, 4000, 2400, 1600, or 1200). This is a design-intent decision, not just a record of today’s approach — if a lower-minimums approach is forecast, the RDC reflects that intent.

Step 5 — Assemble the code

Concatenate the three: AAC–ADG–RVR. A Boeing 737-family runway (AAC C, ADG III) planned for a 1/2-mile-minimum approach yields C-III-2400. A small single-engine GA runway with only visual approaches might be A-I-VIS. The code is now the lookup key for the rest of the design.

Why the RDC matters

The RDC is not a label — it is the input that selects the dimensional standards. The code keys into the design-standards tables (the AC Appendix G data, implemented as the Runway Design Standards Matrix) that set the Runway Safety Area (RSA), Runway Object Free Area (ROFA), Runway Protection Zone (RPZ), runway-to-taxiway separation, holding-position distance, and obstacle clearance surfaces. Change the critical aircraft and you can change every one of those dimensions at once.

That cascade is why the critical aircraft and the RDC are the foundation of a defensible design. A runway built to the wrong RDC carries safety areas, protection zones, and separations that are either non-compliant or needlessly oversized — and the citation trail back to the critical-aircraft determination is what makes the design hold up in a planning study or ALP narrative.

RDC components at a glance
Component	Form	Driven by	Source
AAC	Letter A–E	Approach speed (1.3 V_SO)	Table 1-1
ADG	Numeral I–VI	Wingspan or tail height (more demanding)	Table 1-2
Visibility	VIS / RVR ft	Lowest planned approach minimum	§3.2

Try it in AvPlot

Find an aircraft’s AAC and ADG to build your RDC

The ADG/TDG quick reference reads approach speed and wingspan straight off the aircraft, giving you the first two characters of the RDC instantly.

Open ADG/TDG →

This article is a reference summary for planning use, not a substitute for the governing FAA text. Citations refer to AC 150/5300-13B (Airport Design) Change 1, §3.2. Always verify dimensional values and classification logic against the current AC before issuing a design product. See the full airport planning glossary or the AvPlot toolkit.