Intermediate Holding Position Light for Airfield Ground Lighting

What It Is

Intermediate holding position lights are used at intermediate holding positions established away from the runway holding position, and are particularly relevant where enhanced visual identification is required during reduced-visibility operations.

Under the ICAO arrangement they consist of three fixed, unidirectional yellow lights arranged symmetrically about, and at right angles to, the taxiway centreline, with one light on the centreline and one on each side.

Selected According To

• Intermediate holding-position marking
• Taxiway geometry and intersection arrangement
• Visibility / RVR requirement
• Presence or absence of a stop bar
• Taxiway centreline lighting
• Light colour and fixture direction
• Fixture spacing and inset housing
• Series-circuit characteristics
• Control and monitoring requirements
• Pavement configuration
• Project technical specification

The System Provides

• Clear holding-position identification
• Improved conspicuity during reduced visibility
• Visual coordination with taxiway markings
• Directional visibility toward approaching aircraft
• A consistent visual reference across the taxiway
• Integration with taxiway centreline lighting
• Reliable operation within the AGL system

Holding Point, Not Stop-and-Go

Unlike a stop bar, an intermediate holding position light is generally intended to identify a holding point rather than provide the controlled stop-and-go function associated with an illuminated stop bar.

The ICAO Arrangement

• Three lights
• Fixed operation
• Unidirectional output
• Yellow colour
• Visible in the direction of approach
• Symmetrical about the taxiway centreline
• Positioned at right angles to the centreline
• Individual light spacing of 1.5 m

Simplified Arrangement

TAXIWAY
────────────────────────────────────
        ●   ●   ●      ← yellow holding lights
        ↑   ↑   ↑
───────────────┼────────────────────  ← holding-position marking
               │
        TAXIWAY CENTRELINE

The exact position must be coordinated with the approved intermediate holding-position marking.

Light Location

ICAO specifies that the lights are located along the intermediate holding-position marking, 0.3 m before the marking.

The relationship that matters is holding-position marking + fixture location + taxiway centreline. Survey and set out the installation from the approved airport drawing.

Fixture Spacing

The standard ICAO configuration specifies 1.5 m between individual lights, creating the characteristic pattern:

Maintain the spacing accurately so the visual pattern corresponds to the approved design.

Colour and Distribution

ICAO specifies fixed unidirectional yellow output toward the direction of approach, with a light distribution similar to taxiway centreline lights where such centreline lights are provided.

Review the fixture for yellow colour, chromaticity, directionality, intensity, beam distribution, optical axis and viewing direction.

Important Optical Parameters

• Unidirectional output
• Main beam direction
• Horizontal distribution
• Vertical distribution
• Optical axis
• Intensity
• Colour performance
• Viewing sector

Typical Installation

• In-pavement holding-position fixture
• Housing
• Yellow optical lens
• LED / light-source module
• Optical assembly
• Mounting hardware
• Sealing gasket
• Drainage arrangement
• Secondary cable
• Isolating transformer
• Primary connector

Pavement & Housing Coordination

Treat the fixture and housing as a coordinated pavement installation. Verify:

• Housing and fixture dimensions
• Installation depth and pavement cut-out
• Fixture seating and fasteners
• Drainage and sealing
• Cable routing and maintenance access

The manufacturer's approved installation drawing should control all dimensional requirements.

Taxiway Centreline Light

Provides continuous longitudinal guidance along the aircraft route. The intermediate holding lights identify where the aircraft must hold, then the centreline continues.

Stop Bar vs Holding Lights

The two should not be presented as interchangeable. A stop bar gives a controlled red stop indication associated with movement authorization and interlocking. ICAO recommends intermediate holding position lights where there is no need for stop-and-go signals. The project design determines which visual aid is appropriate.

ICAO Provision

ICAO specifies intermediate holding position lights at designated intermediate holding positions intended for RVR below 350 m, unless a stop bar has been installed.

Review Together With

• Holding-position layout
• Taxiway centreline lighting
• Stop bars and runway guard lights
• ALCMS
• Surface movement procedures

Parameters to Verify

• Series-circuit current
• Isolating-transformer rating
• Fixture input characteristics
• Power consumption
• Connector configuration
• Secondary cable
• Intensity control
• Monitoring requirements

Before Adding or Replacing Lights

Confirm CCR output current, existing circuit configuration, fixture electrical characteristics, transformer rating, number of fixtures, primary and secondary cable, connector system, intensity steps and monitoring.

Incorrect coordination may cause low or excessive intensity, uneven illumination, circuit instability, transformer stress, premature failure or monitoring faults.

Potential Advantages

• Long operating life
• Reduced lamp replacement
• Lower maintenance
• Stable yellow output
• Controlled optical distribution
• Consistent light performance
• Reduced energy consumption
• Compatibility with modern AGL systems

Compliance Is Not Automatic

LED technology alone does not establish compliance. The complete product must satisfy applicable photometric, electrical, environmental and mechanical requirements.

Typical Construction

• High-strength in-pavement body
• Optical lens and yellow optical assembly
• LED module
• Reflector / optical system
• Sealing gasket and fasteners
• Secondary cable interface
• Housing and drainage provisions

Confirm exact materials and dimensions from the manufacturer's approved technical documentation.

Exposure

• Rain and water ingress
• Dust and humidity
• Temperature variation and UV
• Corrosion and vibration
• Aircraft movement and mechanical loading
• Pavement contamination
• Cleaning chemicals

For inset installations, watch water ingress + drainage + sealing + pavement interface + mechanical loading.