An approach light is a type of navigation or signal light used to guide a vehicle, aircraft, or ship as it approaches a runway, harbor, tunnel, bridge, or other critical area. These lights aid safety, visibility, and orientation during the approach.
1. Applications of approach lights
✈ Aviation (Approach Lighting System - ALS)
In aviation, approach lights are an essential part of runway lighting and help pilots land safely, especially in poor visibility.
- White or red lights → Placed before the runway as horizontal or stacked rows .
- Sequenced Flashing Lights (SFL) → Flashing lights that emphasize the runway direction .
- Precision Approach Path Indicator (PAPI) → Red and white lights next to the runway indicate the correct descent angle .
🚢 Shipping
In ports and locks, approach lights guide vessels to the correct moorings or channel markers .
- Red and green lights → Indicate safe approach routes.
- Line lights on harbors and docks → Help captains position the ship correctly.
🚗 Roads and tunnels
On the road, approach lights are used to guide drivers in:
- Tunnels → Flashing lights or warning lights before tunnel entrances.
- Bridges → Red or yellow lights at movable bridges to warn approaching traffic.
🚂 Railways
At railway crossings, approach lights warn of an approaching train.
- Flashing red lights → Stopping required.
- White lights → Indicate that the crossing is clear.
2. Different types of approach lights
| Type | Application | To colour |
|---|---|---|
| Aviation approach lights (ALS, PAPI, SFL) | Runway approach | White, red |
| Port & shipping lights | Navigation in ports | Red, green, white |
| Tunnel & bridge lights | Warning systems | Red, yellow, white |
| Level crossings | Train warning | Red, white |
💡 In short:
An approach light is an essential visual aid used in aviation, shipping, road traffic and railways to navigate safely and correctly to a destination.