Taxiway Fillet Tool — Tool Guide

Coming Soon AC 150/5300-13B CHG 1 · APPENDIX J · ALL GUIDES

The Taxiway Fillet Tool computes taxiway intersection fillet geometry per AC 150/5300-13B Chg 1, Appendix J, consistent with the methodology of the FAA Taxiway Fillet Design Tool V3. You pick the critical aircraft's Taxiway Design Group and enter the deflection angle for each turn; the tool derives the fillet radius (R-CL), the R-Fillet radius where it applies, the arc length, and the arc span, draws a live on-page geometry preview, and exports construction-ready fillet linework as a layered DXF.

It replaces the workflow of running the FAA spreadsheet tool, reading dimensions out of the Appendix J tables, and redrafting the result in CAD — the geometry is shown as you type, every result carries its citation trail, and the DXF arrives already drawn.

This tool is built and in pre-release; it will open from the home page when released. This guide documents the full workflow.

Who It's For & When to Use It

Airport planners and designers laying out taxiway intersections, taxiway connectors, and apron entrances for design reports, planning studies, and ALP development. Use it when a new or reconfigured intersection needs fillet geometry sized to the critical design aircraft, when checking whether existing fillets meet current Appendix J standards for a larger design aircraft, or when you need defensible fillet linework in CAD without rebuilding the FAA tool's output by hand.

How to Use It

The tool is a single screen. The former three-step wizard has been collapsed: Setup, Intersection Angles, and Review & Generate are all visible at once and separated by section rules, so the live preview and results update under your eye as you change inputs.

  1. Name the project. Enter a Project Name (e.g. "KLAX Taxiway Charlie Fillet Design"). The New / Open / Save controls store and reload the design through the project manager.
  2. Select the Taxiway Design Group. The Taxiway Design Group (TDG) dropdown is the primary input — pick 1A through 6 directly (AC 150/5300-13B Chg 1 Table 3-6, by critical-aircraft wheelbase and wingspan).
  3. Or classify by critical aircraft (optional). If you do not know the TDG, use the Aircraft Library tab to search the FAA database by code, manufacturer, or model, or the Custom Dimensions tab to enter wingspan, tail height, wheelbase, and MGW outer-to-outer. Classifying returns ADG and TDG and sets the TDG dropdown automatically; where the library is missing dimensions, the amber fields prompt you to supply them from the POH/AFM.
  4. Read the TDG parameters. Once a TDG is set, the read-only TDG Parameters populate — Wheelbase (CMG), Taxiway Half-Width, Min Fillet Radius, and R-Fillet Radius — so the design basis is derived from the standard, never hand-entered.
  5. Set site options. Enter an optional Edge Light Offset (ft) (taxiway edge to edge-light centerline; leave blank if no edge lights) and tick RVR < 1,200 ft under Visibility Category for visibility-critical (low-visibility) operations.
  6. Enter each intersection angle. In the Intersection Angles section, give the turn a Label / Name (e.g. "TWY A × TWY B") and the Intersection Angle θ — the total deflection between taxiway centerlines, from 5° to 175°. Use + Add intersection to build a repeatable list of turns; each card can be removed. A θ > 90° turn raises a "verify design intent" warning badge.
  7. Watch the live geometry preview. Each card draws a Live Geometry Preview SVG — the two taxiway centerlines, the inner pavement edge legs, the fillet arc, the R-CL radius line, and the deflection and R-Fillet labels — that redraws the instant TDG or θ changes. Below it, read-only fields show Fillet Radius R, R-Fillet Radius, and Arc Length.
  8. Confirm the Result Block. Each intersection's Result Block states the computed Fillet Radius (R-CL), R-Fillet, Arc Length, and Arc Span, the Controlling Standard, the Logic branch that governed (Δ ≤ 90° vs > 90°, with the spiral entry angle φ₀), the Assumptions, any Warnings, and the Data Vintage. Copy block puts the full citation-trailed result on the clipboard for a design narrative.
  9. Review and export. The Review & Generate section lists every intersection in one table (Label, θ, Fillet Radius, R-Fillet, Arc Length, Arc Span). Generate Fillet DXF produces the layered DXF for the intersection; Print Summary renders a print-ready record of the design.

Key Features

  • TDG as a first-class input. The design group is selected directly (1A–6); the aircraft-classify path is an optional shortcut that only sets the TDG.
  • Live SVG geometry preview. Edge legs, fillet arc, R-CL radius line, deflection angle, and R-Fillet label redraw as TDG and θ change — the same computation that feeds the DXF, so the picture and the output agree.
  • Repeatable intersection list. Add, label, and remove multiple turns; each gets its own preview, read-only results, and Result Block.
  • Citation-trailed Result Block. Result, Controlling Standard, Logic, Assumptions, Warnings, and Data Vintage on every intersection, with one-click Copy block.
  • Derived TDG parameters. Wheelbase (CMG), taxiway half-width, minimum fillet radius, and R-Fillet radius shown read-only from the standard.
  • Site conditions. Optional edge-light offset and an RVR < 1,200 ft low-visibility flag.
  • Exports. Layered DXF download, Print Summary, and per-intersection Copy block.

FAA References

  • AC 150/5300-13B Chg 1 (8/16/2024), Airport Design, Table 3-6 — Taxiway Design Group definition by critical-aircraft wheelbase and wingspan.
  • AC 150/5300-13B Chg 1, Appendix J, Tables J-1 through J-8 — governing standard for taxiway intersection fillet design, including the published R-CL and R-Fillet design values.
  • FAA Taxiway Fillet Design Tool V3 User's Guide — methodology reference; R-Fillet is 0 when the deflection Δ ≤ 90°, and the fillet arc uses an Euler-spiral basis. This tool is consistent with the V3 tool's computational approach.

Limitations & Disclaimers

AvPlot is technical planning production support — accurate enough for design reports, planning studies, and ALP narratives. It is not a replacement for stamped engineering or construction documents. Verify all geometry against current FAA publications before use in official Airport Layout Plans or construction submittals.

  • Each DXF describes a single taxiway-to-taxiway turn; complex multi-leg junctions should be decomposed into individual intersections and exported separately.
  • The deflection angle is constrained to 5°–175°; a turn beyond 90° is flagged for design-intent review, not blocked.
  • Where the configuration matches a published Appendix J case, the table value is used verbatim; otherwise the geometry is synthesized with the Appendix J swept-envelope method.
  • Fillet geometry is generated in a local coordinate frame; placing the linework at real-world coordinates and rotation happens in your CAD environment.

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Tips & Best Practices

  • If you already know the design group, skip the aircraft path and pick the TDG directly — it is faster and the parameters populate immediately.
  • When classifying a custom aircraft, enter the greater of wheelbase and cockpit-to-main-gear distance so the TDG is sized to the controlling dimension.
  • Use the live preview to sanity-check the turn before exporting — the deflection label and R-Fillet note confirm which Appendix J branch is governing.
  • Copy each Result Block into your design narrative; the captured Controlling Standard, Logic, and Data Vintage make the geometry defensible without retyping citations.
  • Build wide turns as separate intersections rather than one oversized angle, and verify any θ > 90° turn against the design intent the warning flags.

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