Acute Angle Exit — Tool Guide

Coming Soon AC 150/5300-13B CHG 1 · EULER-SPIRAL EXIT GEOMETRY · ALL GUIDES

The Acute Angle Exit tool designs the geometry of a high-speed (acute-angle) runway exit taxiway — the Euler-spiral entry curve, the minimum turn radius, the nose-gear steering angle, and the total exit length — for a given critical aircraft, exit curve radius, exit angle, and runway-centerline-to-taxiway-centerline separation, per AC 150/5300-13B. It outputs a CAD-ready DXF you can place directly in a drawing.

It replaces the usual workflow of laying out the spiral transition by hand, iterating the turn radius against the separation, and re-deriving the exit length each time the design aircraft or angle changes. This tool is in pre-release — the workspace described here reflects what it does when it opens; the Euler-spiral geometry engine is already live behind it.

Open the Acute Angle Exit tool →

Who It's For & When to Use It

Airport planners and designers laying out or checking high-speed turnoffs on a runway. Use it when you are evaluating a new acute-angle exit location, comparing exit angles or curve radii against a fixed runway-to-parallel-taxiway separation, or documenting the exit geometry behind an ALP or design report. The acute-angle exit reduces runway occupancy time, so its placement and geometry are recurring questions in capacity and design studies.

How to Use It

Name the project. For example, KLAX RW 24L High Speed Exit Design. The name labels the design and the generated DXF.
Set the critical aircraft and TDG. Search the aircraft library by FAA code, manufacturer, or model, or enter custom dimensions (wingspan, MGW outer-to-outer, tail height, and wheelbase or CMG). The Taxiway Design Group is classified from the critical aircraft wheelbase per AC 150/5300-13B Table 3-6.
Set the exit curve radius R1. The radius of the initial high-speed exit curve — typically 1,500 ft for a 30° acute-angle exit.
Set the exit angle. Between 1° and 89°; 30° is the standard acute-angle high-speed exit. The angle drives the Euler-spiral transition.
Add each exit. Give an exit label and the runway centerline-to-taxiway centerline separation (ft) for each turnoff.
Compute. The tool returns the minimum turn radius R2, the nose-gear steering angle, and the total exit length for each exit, with the Euler-spiral entry curve solved per the FAA acute-angle exit geometry.
Generate the DXF. The CAD-ready export contains the exit centerline, curves, and labels drawn to scale for direct placement in your drawing.

Key Features

Euler-spiral (clothoid) transition. The entry curve uses a true spiral transition between the runway and the constant-radius turn, matching the FAA Acute Angle Exit geometry rather than a single circular arc.
Critical-aircraft driven. TDG and the steering check follow from the design aircraft — search the shared aircraft library or enter custom gear dimensions.
Separation-aware. Each exit solves against its own runway-to-taxiway centerline separation, so parallel-taxiway geometry is respected.
Multiple exits per project. Lay out and compare several turnoffs in one session.
CAD-ready DXF. The export drops straight into a drawing, with the geometry labeled and to scale.
Citation trail. Geometry and TDG classification cite AC 150/5300-13B.

FAA References

AC 150/5300-13B Chg 1, Airport Design — governing standard for taxiway and exit geometry; TDG classification per Table 3-6 (critical aircraft wheelbase).
FAA Acute Angle Exit geometry — the Euler-spiral entry-curve method AvPlot's engine reproduces; AvPlot's implementation is benchmarked against the FAA tool (see docs/benchmark notes).

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, design submittals, or construction documents.

The DXF arc coordinate system differs from the FAA Excel tool's; the arc is geometrically correct (tangent to both edge legs within a fraction of a foot) but absolute coordinates are not byte-comparable to the spreadsheet — this is expected.
The tool designs the exit geometry; it does not site the exit along the runway or evaluate runway occupancy time / capacity benefit.

Related Tools

Taxiway Fillet Tool — fillet geometry and DXF for taxiway/taxiway and taxiway/exit intersections (guide).
Taxiway Separation Standards — the runway-to-taxiway and taxiway-to-taxiway separations the exit must satisfy (guide).
Runway Linework Generator — draws the full runway and surface linework the exit ties into (guide).

Tips & Best Practices

Start from the design aircraft: look it up in the Aircraft Classification Library so the TDG and gear geometry are defensible, rather than typing dimensions from memory.
Hold the angle and separation fixed and vary R1 (or vice versa) to see how the exit length and turn radius trade off before committing to a layout.
Confirm the runway-to-taxiway separation against the Taxiway Separation Standards for your ADG before designing the turnoff.

Taxiway Design: Fillet Geometry & Separation Standards — how exit and taxiway geometry fits the broader taxiway design rules.
What Changed in AC 150/5300-13B Change 1 — the current governing edition for taxiway and exit geometry.