The Hong Kong Polytechnic UniversityDepartment of Aeronautical and Aviation Engineering

ARM. INTERCEPT. CAPTURE.

Localiser & Glideslope Capture

Move the initial aircraft position. Watch lateral and vertical guidance capture a synthetic approach while wind changes the ground track.

3D MODEL + LINKED DIAGRAMB · LIVE

Drag to orbit · right-drag to pan · scroll to zoom. Flight-path height and lateral scales are exaggerated for inspection.

Diagram · drag background to pan

Drag the turquoise handles, or focus a handle and use arrow keys. The sliders provide the same controls.

Preparing the calculation…

A · no saved reference

01 / READ THE CHANGE

Track differs from heading

Crosswind alters the ground track. Guidance uses a wind-corrected heading target to remove lateral displacement.

02 / READ THE CHANGE

Capture is a mode change

The vertical path is armed until the aircraft is close to the beam from below and lateral capture has occurred. Starting above can leave it armed throughout.

03 / READ THE CHANGE

A deliberately bounded model

TAS is held ideally and the bank/flight-path responses represent pre-stabilised inner loops. The experiment ends 300 m before the threshold.

THE SAME MODEL, CONNECTED VIEWS

Follow the calculation

B · solid turquoise   A · dashed amber

Compare A and B

QuantityA · savedB · liveB − AUnit

A remains fixed until saved again. Export includes the model version, settings and plotted data.

Equations, assumptions & sources

Read the balance, then connect each symbol to the model. Open a symbol key for definitions and units. Long equations can be scrolled sideways.

01 · Resolve the flight path

x˙=−Vcos⁡(γ)cos⁡(ψ) y˙=Vcos⁡(γ)sin⁡(ψ)+wcross h˙=Vsin⁡(γ)

The aircraft approaches the runway as x decreases. Crosswind affects ground track.

Symbols & units
x,y,h
Distance to threshold, lateral displacement and height, m.
V,wcross
True airspeed and signed crosswind component, m/s.
γ,ψ
Flight-path angle (positive climbing) and heading deviation from the approach axis, rad.

02 · Bank changes heading

ψ˙=gtan⁡(φ)Vcos⁡(γ)

The banked-turn kinematics link lateral guidance to aircraft heading.

Symbols & units
φ,g
Bank angle, rad; gravitational acceleration 9.80665 m/s².

03 · Follow the reference beam

href=15m+xtan⁡(3°)

The illustrative beam passes 15 m above the threshold at a 3° approach angle.

Symbols & units
href
Target beam height, m. This geometric model does not provide flare or autoland behaviour.

Synthetic straight 3° path, 9 km start distance, no airport procedure or radio propagation model. Bank limited to 25°, flight-path command −6° to +1°, bank lag 2 s and flight-path lag 4 s. Pitch display uses γ + 3° illustrative incidence. No stall, thrust/energy constraints, terrain, flare or autoland.

MIT · stability and control notes ↗FAA · aviation handbook library ↗

Physical relations and teaching sources support the stated concepts. Generic coefficients are explicitly illustrative; they are not measured manufacturer data. Numerical verification is separate from experimental validation. Model version: applied-labs-v1.1.

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