Approach Side Row Light for Airfield Ground Lighting

What It Is

Approach side-row lights form part of configured approach lighting systems, providing lateral visual references on either side of the extended runway centreline.

With centreline lights and crossbars they create a recognizable geometric pattern. They are particularly important in precision approach Category II and III systems, supporting operations in reduced visibility.

Helps Pilots Assess

• Runway alignment
• Lateral position
• Roll attitude
• Approach orientation
• Aircraft relationship to the runway centreline

Role

The approach centreline gives the longitudinal reference; the side rows give a lateral frame around it. They are an integral element of the complete approach-lighting geometry.

The Combined Arrangement Helps Interpret

• Runway approach alignment
• Lateral deviation and roll attitude
• Approach orientation
• Distance and perspective
• Relationship between centreline and threshold

ICAO System Comprises

• One centreline row (wherever possible 900 m from threshold)
• Two side rows (270 m; 240 m alternative subject to serviceability)
• Two crossbars at 150 m and 300 m

Conceptual Layout

Side rows · centreline · runway threshold below

ICAO Category II/III Gauge

• Not less than 18 m
• Not more than 22.5 m
• Preferably 18 m
• In any case equal to the touchdown-zone-light gauge

Why It Matters

The relationship with TDZ lights maintains a consistent visual geometry between the approach area and the runway touchdown zone.

Standard Arrangement

Side rows extend 270 m from the threshold.

Reduced Arrangement

Where the serviceability level can be demonstrated, side rows may extend 240 m.

ICAO Category II/III

• Crossbar at 150 m — fills visual gaps between centreline and side-row elements
• Crossbar at 300 m — strong transverse reference within the approach system
• Crossbars connect or visually relate centreline and side-row elements

Geometry

Side Row → Crossbar → Centreline → Crossbar → Side Row creates a three-dimensional visual reference: longitudinal + lateral + transverse. Select side rows together with the corresponding centreline and crossbar assemblies.

Colour

ICAO Category II/III side rows provide red visual references. FAA ALSF-2 uses steady-burning red side-row-bar lamps (nine bars on each side, 54 lamps in total).

Verify Against

• Approach category and authority
• Approach lighting system and project drawing
• Fixture configuration and photometric specification

ALSF-2

A high-intensity approach lighting system for Category II/III instrument approaches, providing runway alignment, height perception, roll guidance and horizontal references. Typical arrangement: green threshold lights, red side-row bars, high-intensity white lights and sequenced flashers.

Side-Row Bars

Nine side-row bars on each side of the ALS centreline (18 bars, 54 red lamps in total), 100 ft longitudinal spacing, three red lamps per bar.

ICAO Requirement

The gauge between the innermost side-row lights should in any case equal the gauge of the touchdown-zone lights, giving visual continuity from approach to touchdown.

In Technical Review

Check the approach side-row layout against the TDZ layout rather than reviewing it independently.

Important Characteristics

• Red light output where applicable
• Directional optical arrangement, optical axis
• Horizontal and vertical beam coverage
• Main beam, intensity, chromaticity
• Viewing sector

The side rows must be clearly identifiable while coherent with the centreline and crossbars.

Complete Array

Side-row lights are precision visual-aid equipment. They must satisfy the applicable photometric requirements as a complete array, not only as an individual fitting.

Potential Advantages

• Long operating life
• Reduced lamp replacement and maintenance
• Stable red output and consistent colour
• Controlled optical distribution
• Reduced energy consumption
• Compatibility with modern control and monitoring systems

Compliance

Where a lamp-based system is specified, match lamp, optical assembly and electrical components to the approved system. LED technology alone does not establish compliance.

Parameters To Verify

• Operating current and circuit type
• Power consumption and CCR requirements
• Isolation transformer where applicable
• Secondary connection and cable arrangement
• Intensity control, monitoring, control interface

Intensity Control

• High, medium and low intensity
• Multiple intensity steps
• Ambient-condition-dependent operation

Without considering the system’s intensity settings, a fixture may not deliver the required visual balance with centreline and crossbar elements.

Do Not Confuse With

• Sequenced flashers
• Centreline light bars
• Crossbar lights
• Runway threshold lights

Design Principle

Design the system so the different light functions remain visually distinguishable. The side rows remain a separate visual element.

May Be Installed As

• Elevated fixtures, light bars, barrettes
• Modular LED assemblies
• Low-level approach-light supports
• System-specific support structures

Consider light height, orientation, frangibility, alignment, crossbar and centreline relationship, and maintenance access.

Approach-Area Support Structures

• Frangibility and wind loading
• Structural stability
• Approach surface and obstacle environment
• Drainage, maintenance access, cable routing

Side rows lie outside the runway pavement; select supports as part of the approved system.

Environmental Exposure

• Rain, dust, humidity
• Temperature changes, UV, corrosion
• Wind, vibration, wildlife, maintenance activity

Installation Alignment

• Extended runway centreline, side-row gauge
• Longitudinal station, fixture elevation
• Optical azimuth, beam axis
• Crossbar, TDZ and threshold relationship

Incorrect installation can distort the visual geometry even when every fixture is operational.

Visual & Electrical

• Fixture, lens, red output, position, stationing, spacing
• Side-row symmetry, alignment, crossbar relationship, supports, cables
• Continuity, insulation resistance, CCR output
• Transformer verification where applicable, connector condition
• Intensity-step and control-system operation

Photometric & System-Level

• Red colour, intensity, horizontal and vertical coverage
• Optical direction, side-row alignment, system consistency
• Check Centreline + Side Rows + Crossbars + Threshold + TDZ
• Visual arrangement must match the approved drawing

Optical & Mechanical

• Lens cleanliness and damage, red colour, light output
• Beam distribution and contamination
• Support condition, fixture alignment, fasteners
• Corrosion, frangibility, physical damage

Electrical & Geometry

• Cable, connector, transformer, CCR
• Control panel and monitoring
• Side-row gauge and longitudinal spacing
• Centreline alignment, crossbar, threshold and TDZ relationship

ICAO

• Annex 14, Volume I (Chapter 5, approach lighting systems) and Doc 9157 Part 4; confirm the current edition and amendments on the ICAO Store before procurement
• Centreline row, wherever possible 900 m from threshold; lights at 30 m intervals, innermost 30 m from threshold
• Two side rows, 270 m (240 m alternative where serviceability is demonstrated), aligned with centreline stations
• 30 m spacing normally; 60 m alternative where demonstrated
• Gauge 18–22.5 m, preferably 18 m, equal to TDZ gauge
• Crossbars at 150 m and 300 m

FAA

AC 150/5340-30J — Design and Installation Details for Airport Visual Aids (active); ALSF-2 installation criteria are in Order JO 6850.2C below.

AC 150/5345-45C — Low-Impact Resistant (LIR) structures, for frangible approach-light supports.

ALSF-2 uses red side-row bars with white steady-burning centreline elements, green threshold lights and sequenced flashers, supporting Category II/III approaches. Order JO 6850.2C (Visual Guidance Lighting Systems, 30 August 2022) depicts nine side-row bars per side, three red lights per bar at 100 ft spacing.

Use FAA’s current airport-lighting specifications for exact fixture type, photometry, mounting and certification.