Runway End Identifier Lights (REILs) – High-Intensity Flashing Lights at the Runway Threshold

Overview

Runway End Identifier Lights (REILs) are a critical component of airport lighting systems, designed to provide pilots with a clear, unmistakable visual cue marking the beginning of a runway. Consisting of two synchronized, high-intensity flashing lights—one on each side of the runway threshold—REILs rapidly attract pilot attention, helping them identify the correct runway in all conditions, including at night, in poor weather, or against visually complex backgrounds.

REILs are installed in accordance with international (ICAO Annex 14) and national (FAA AC 150/5345-28) standards and are particularly important at airports lacking a full approach lighting system (ALS) or where the threshold can be difficult to distinguish from surrounding terrain or lighting.

Purpose and Function

The primary function of REILs is to provide a rapid, highly conspicuous indication of the runway threshold. This is especially vital when:

• Visual contrast is low (e.g., snow-covered, grass, or desert airfields)
• Background lighting is complex (e.g., urban environments)
• Visibility is reduced (e.g., fog, rain, night operations)
• Approach lighting systems are absent or minimal

By emitting synchronized, high-intensity white flashes toward the approach direction, REILs serve as a unique visual signature that stands out from steady-burning threshold, edge, or centerline lights. This reduces the risk of pilots confusing taxiways, roads, or other runways for the intended landing surface, improving overall safety.

REILs are typically operational only when needed—activated by air traffic control, automatically via sensors, or by pilots themselves at uncontrolled airports.

Technical Description and Construction

A standard REIL system consists of two identical light units, each installed at the lateral edges of a runway threshold. Key features include:

• Robust, weather-resistant enclosures (NEMA 4 or IP66 rated)
• Frangible (breakaway) mounting bases for safety in case of accidental impact
• High-intensity light sources (either traditional xenon flash tubes or modern LEDs)
• Precision optics to focus light in the defined approach sector (typically 10° either side of runway centerline, and 3° vertical spread)
• Electronic synchronization to ensure both lights flash simultaneously (60–120 flashes per minute)
• Remote or automated control and monitoring capabilities

Typical Installation

• Lateral offset: 3–6 meters (10–20 feet) from the runway edge
• Height: Less than 0.7 meters (28 inches) above ground
• Alignment: Symmetrically positioned about the runway centerline, aimed toward the approach path

Placement and Configuration

REILs are installed to maximize visibility for approaching aircraft while ensuring they do not obstruct aircraft movement or dazzle ground personnel. The optimal placement, as specified by ICAO and FAA, provides a clear, unmistakable threshold marker from any approach angle within the standard approach sector.

For temporary or portable use (e.g., military, disaster relief, construction), REILs can be mounted on robust bases with integrated power supplies and wireless controls.

Comparison with Other Runway Lighting Systems

REILs provide a unique, high-contrast flashing signal, serving as a cost-effective alternative to full approach lighting systems for threshold identification.

Types of REILs

By Directionality:

• Unidirectional: Emit light toward the approach zone, maximizing intensity for arriving aircraft and minimizing stray light.
• Omnidirectional: Emit light in all directions (less common, used for specific applications).

By Technology:

• Xenon Flash Lamp REILs: Traditional, high-voltage systems requiring regular maintenance.
• LED REILs: Modern, energy-efficient, with longer lifespan, lower maintenance, and built-in diagnostics—now the industry standard.

Technical Specifications

Compliance and Regulatory Standards

• ICAO Annex 14, Volume I: Specifies REIL placement, flash characteristics, color, and intensity. Mandates use where threshold identification is problematic.
• FAA AC 150/5345-28 (L-880/L-881): U.S. standards for photometric, mechanical, and operational characteristics, including pilot control and remote operation.
• Other Standards: Transport Canada TP 312, EASA CS-ADR-DSN, UK CAA CAP 168, and more.

Certified REIL systems undergo rigorous photometric, environmental, and safety testing to ensure compliance.

Advancements: LED vs. Xenon REILs

LED REILs provide superior performance, safety, and efficiency, making them the preferred choice for new installations and upgrades.

Installation and Integration

REILs are installed according to strict airport lighting design standards, emphasizing:

• Secure, level foundations (reinforced concrete or pre-cast slabs)
• Frangible mounting for safety
• Weather-sealed, corrosion-resistant wiring and terminations
• Integration with existing airfield lighting control and monitoring systems (manual, remote, wireless, or pilot-controlled)

Modern systems support remote monitoring, fault alerts, and adaptive intensity control.

Control and Power Options

• Manual Control: Airfield lighting panel or local switch
• Remote Control: Air traffic control or airport operations center
• Wireless Control: For temporary or remote deployable systems
• Pilot-Activated Lighting (PAL/PCL): Pilots activate REILs via radio at uncontrolled airports

Power Sources:

• AC Mains: Standard fixed installations
• DC Power/Solar: For remote, portable, or backup systems
• Constant Current Regulator (CCR): Commonly used on airfield lighting circuits

Operational Scenarios and Use Cases

• Urban airports with bright backgrounds: REILs stand out from city lights.
• Remote or low-contrast airports: Snow, grass, or desert runways benefit from improved threshold visibility.
• Airports without full ALS: REILs provide the minimum required visual aid for instrument approaches.
• Temporary/portable fields: Military, disaster relief, or construction sites use portable REILs.
• Low-visibility operations: REILs supplement runway lights during fog, rain, or snow.

Maintenance and Reliability

Xenon REILs: Require regular lamp replacement, high-voltage inspection, and cleaning; subject to ozone degradation.

LED REILs: Minimal maintenance (mainly cleaning and operational checks), with built-in diagnostics and no high-voltage risks.

All REILs are engineered for harsh environmental conditions and built with safety in mind (frangible supports, sealed enclosures).

Advantages of REILs

• Instant threshold identification in all conditions
• Improved safety and reduced risk of misidentification
• Flexible operation (permanent or temporary, any runway)
• Regulatory compliance (ICAO, FAA, etc.)
• Cost-effective, especially compared to full ALS
• Energy-efficient, low-maintenance with LED technology

Abbreviations and Related Terms

More Resources

• ICAO Annex 14 - Aerodromes
• FAA AC 150/5345-28 - Specification for REIL
• Transport Canada TP 312 - Aerodrome Standards

Runway End Identifier Lights (REILs) are a simple, highly effective way to ensure safe, rapid threshold identification for pilots in any environment. Whether as a permanent installation or portable solution, modern LED REILs offer unmatched reliability, efficiency, and compliance.

If you’re considering new REILs or upgrading your airfield lighting, contact our team or schedule a demo to learn more about the latest solutions.