# Aerodrome Supplementary Guidance: Declared Distances, Lighting Reference, and Sign Colors

> Review supplementary aerodrome guidance on declared distances, threshold-based approach lighting references, and mandatory sign color conventions.

- **Subject:** 010 — Air Law
- **Section:** 010-09 — Aerodromes
- **Topic code:** 010-09-08
- **Last reviewed:** 2026-03-27
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/air-law/aerodromes/supplementary-guidance-material/

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## Summary of Declared Distances

| Distance | Definition | Formula (Simplified) |
| :--- | :--- | :--- |
| **TORA** | Take-Off Run Available | Physical runway suitable for takeoff roll |
| **TODA** | Take-Off Distance Available | TORA + Clearway (CWY) |
| **ASDA** | Accelerate-Stop Distance Available | TORA + Stopway (STW) |
| **LDA** | Landing Distance Available | Runway available for landing (affected by displaced threshold) |

*   **TODA includes the Clearway** (may be over water).
*   **ASDA includes the Stopway** (load-bearing pavement for emergency braking).
*   If no Stopway, no Clearway, and no displaced threshold: **TORA = TODA = ASDA = LDA**.

## Approach Lighting
Approach lighting measurement is always taken from the **threshold** outwards.

### Sign Colors (Summary)
*   **Mandatory Instruction Signs:** White on Red (e.g., STOP, NO ENTRY).
*   **Location Signs:** Yellow on Black.
*   **Direction/Destination Signs:** Black on Yellow.

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