Halogen Lamp – Incandescent Lamp with Halogen Gas – Airport Lighting: Comprehensive Glossary

What is a Halogen Lamp?

A halogen lamp is a form of incandescent lighting that incorporates a tungsten filament and a halogen gas (most often iodine or bromine) within a compact, high-temperature-resistant quartz glass envelope. The fundamental advantage of halogen lamps over traditional incandescent lamps is the halogen cycle, a chemical process that redeposits evaporated tungsten back onto the filament. This extends filament life, reduces blackening of the lamp envelope, and allows operation at higher temperatures—producing a brighter, whiter light.

Halogen lamps are a mainstay of airport and airfield ground lighting, owing to their instant-on capability, consistent color temperature (typically 2950–3300K), robust mechanical design, and reliable operation in demanding environments. Their mercury-free construction aligns with modern environmental regulations, and their compatibility with legacy electrical systems ensures easy integration into existing infrastructure.

Key Components and Features

Tungsten Filament

The tungsten filament is the heart of a halogen lamp, chosen for its extremely high melting point (3,422°C) and low vapor pressure. In halogen lamps, the filament is engineered for higher temperature operation than in standard incandescent bulbs, which directly increases both luminous efficacy and color quality.

Precision filament alignment is vital in airfield lighting. Precise placement ensures the emitted light meets FAA and ICAO photometric requirements—especially important for runway centerline, edge, and approach lighting, where beam pattern and intensity must be strictly controlled for pilot safety.

Halogen Cycle

The halogen cycle is what sets halogen lamps apart from ordinary incandescents. When the tungsten filament is heated, tungsten atoms vaporize and could blacken the glass envelope. In a halogen lamp, the halogen gas reacts with these atoms, forming a volatile tungsten halide. Near the hot filament, this molecule breaks down, redepositing tungsten on the filament and releasing the halogen to repeat the cycle. This process:

• Prevents envelope blackening
• Extends filament life (1,000–3,000 hours)
• Allows higher operating temperatures for brighter, whiter light
• Maintains stable color and output over the lamp’s lifespan

Quartz Glass Envelope

Halogen lamps use a quartz glass envelope (fused silica), which withstands the elevated operating temperatures and stress of the halogen cycle (up to 1,650°C). Quartz allows for a more compact lamp, precise filament positioning, and excellent resistance to thermal shock and vibration.

Most airfield halogen lamps are UV-filtered or coated to prevent harmful ultraviolet emissions, protecting fixture plastics and personnel.

Current-Controlled Design

Airfield lighting circuits are typically series circuits regulated by current (commonly 6.6A). Halogen lamps are specifically engineered for these circuits, ensuring uniform brightness and robust performance, even as lamp voltages vary due to manufacturing tolerances or aging.

Current-controlled halogen lamps support step dimming, instant-on operation, and compatibility with airfield isolation transformers, making them ideal for regulated airport lighting grids.

Types of Halogen Lamps in Airport Lighting

MR16 Lamps

MR16 (Multifaceted Reflector, 2-inch diameter) lamps use a precision reflector to produce tightly controlled light beams. They are widely used in runway centerline, edge, and guidance sign lighting, where regulatory beam alignment and photometric performance are critical. MR16 lamps are robust, vibration-resistant, and available in a range of wattages and color temperatures.

PAR Lamps (PAR38, PAR56, PAR64)

PAR (Parabolic Aluminized Reflector) lamps come in several sizes—PAR38, PAR56, PAR64—and use a parabolic reflector for focused, intense beams. PAR56 is standard for FAA/ICAO approach lighting systems and obstruction beacons, delivering uniform, high-intensity light over long distances even in exposed, vibration-prone locations.

Tubular Lamps (T3, T4)

T3 and T4 tubular halogen lamps (3/8" and 1/2" diameter) are used for linear or compact lighting applications—such as edge lights and approach bars—where high-intensity, linear light output is needed. They are engineered for current-controlled operation and resist thermal and mechanical stress.

Performance and Regulatory Advantages

Vibration Resistance

Airfield lighting fixtures are exposed to continuous vibration from aircraft, wind, and ground operations. Halogen lamps are built with reinforced filaments, robust bases, and shock-absorbing supports to withstand these challenges, meeting FAA/ICAO durability requirements.

Infrared Radiation

Halogen lamps emit substantial infrared (IR) radiation due to their high operating temperatures. This waste heat helps melt snow and ice from exposed fixtures—a key operational advantage over LEDs. IR output can also support night-vision and vision-enhancement systems used in aviation.

Flicker-Free Operation

Halogen lamps provide flicker-free, stable light at all dimming levels, thanks to their thermal inertia and direct current operation. This is essential for pilot comfort and safety, preventing visual misinterpretations during landing or taxiing.

Dimmability

Halogen lamps support step dimming in airfield series circuits, maintaining stable output and color temperature as current is adjusted (from ~2.8A to 6.6A). This flexibility supports variable lighting needs for day/night, fog, or snow conditions.

Mercury-Free Construction

Halogen lamps are mercury-free, complying with environmental regulations such as the Minamata Convention and simplifying disposal/recycling. This is a significant advantage over some fluorescent and HID lamp technologies.

Color Temperature

Stable color temperature (2950–3300K) ensures neutral, high-contrast white light, critical for clear perception of airfield markings and signals. Halogen lamps maintain this color profile over their service life, delivering uniform visual cues to pilots.

Photometric Output

Precision optical control is a hallmark of halogen lamps, with tightly controlled luminous flux and spatial distribution. This is vital for regulatory compliance (FAA/ICAO) and operational safety, ensuring lights are visible at the required distances and angles.

Applications in Airport and Airfield Lighting

• Runway and Taxiway Centerline/Edge Lights
• Approach Lighting Systems (ALS)
• Visual Approach Slope Indicators (VASI, PAPI)
• Guidance Signs and Beacons
• Obstruction Lighting
• Snow/Ice Melting on Fixture Lenses

Halogen lamps are often chosen for their instant-on performance, compatibility with existing infrastructure, and robust mechanical design. They remain a preferred solution for many airports globally, especially where LED retrofits are not yet practical or where regulatory photometric requirements are stringent.

Regulatory Standards

Halogen lamps for airport lighting are certified to meet strict FAA and ICAO standards for:

• Photometric performance (intensity, beam pattern, color)
• Mechanical durability (vibration, shock, environmental cycling)
• Electrical compatibility (current-controlled series circuits)
• Environmental compliance (mercury-free, hazardous substance restrictions)

Top manufacturers (e.g., OSRAM, Amglo, GE) rigorously test and certify halogen lamps for airfield use, ensuring operational reliability and regulatory compliance.

Summary

A halogen lamp is a high-performance, incandescent light source specifically engineered for demanding applications like airport and airfield lighting. Its unique halogen cycle, tungsten filament, and quartz envelope deliver long life, stable color, and precise photometric output—essential for safe and compliant runway and taxiway illumination.

References & Further Reading:

• ICAO Annex 14 – Aerodromes, Vol. 1: Aerodrome Design and Operations
• FAA AC 150/5345-46 – Specification for Runway and Taxiway Light Fixtures
• OSRAM Airfield Lighting Product Catalog
• Amglo Airfield Lamp Technical Documentation

For more information on advanced airfield lighting solutions, contact our team or request a demo.