What Is an FAA L-864 Obstruction Light?

FAA L-864 obstruction lights are medium-intensity, flashing red lights used to mark tall structures that may pose a hazard to aircraft. They are typically installed at the top of structures over 200 feet above ground level (AGL) as part of an FAA-compliant obstruction lighting system.

L-864 obstruction lights are defined within FAA guidance, including Advisory Circular AC 70/7460-1, which outlines marking and lighting requirements for structures that may affect navigable airspace.

Quick Answer: What Is an FAA L-864 Obstruction Light?

An FAA L-864 obstruction light is a medium-intensity, flashing red light used to mark tall structures at night. These lights are typically installed at the top of structures and are often used together with L-810 lights in FAA red obstruction lighting systems.

Definition: FAA L-864 Obstruction Light

An FAA L-864 obstruction light is a medium-intensity, flashing red aviation light used to mark tall structures that may pose a hazard to aircraft, typically installed as the top beacon on structures requiring obstruction lighting.

What Is an L-864 Obstruction Light?

An L-864 obstruction light is part of the FAA obstruction lighting system used to improve visibility of tall structures at night.

These lights are designed to:

• Emit a flashing red light
• Provide higher visibility than low-intensity lighting
• Mark the highest points of structures

L-864 lights are typically part of an FAA red obstruction lighting system used for nighttime marking of tall structures.

L-864 lights are used primarily for nighttime obstruction marking and are often combined with other lighting systems for daytime or higher-intensity requirements.

L-864 lights flash at a regular interval to improve visibility and draw attention to tall structures, making them more noticeable to pilots at night.

When Are L-864 Lights Used?

L-864 lights are typically used in the following situations:

• On structures over 200 feet above ground level (AGL)
• As the top beacon of tall towers and structures
• When specified as part of an FAA obstruction lighting determination

Final lighting requirements are determined through an FAA obstruction evaluation, which specifies the appropriate lighting system based on structure height, location, and potential impact on navigable airspace.

Common applications include:

• Communication towers
• Broadcast towers
• Wind turbines
• High-rise structures

Typical Use Cases for L-864 Obstruction Lights

• Top beacon on towers exceeding 200 feet
• Primary flashing light in red obstruction lighting systems
• Structures requiring increased nighttime visibility

Key Characteristics of L-864 Lights

LED vs. Incandescent L-864 Lights

Modern L-864 obstruction lights are commonly available in LED configurations.

LED L-864 Lights

• Long service life
• Lower maintenance requirements
• Improved reliability

Incandescent L-864 Lights

• Lower initial cost
• Higher maintenance requirements

For most applications, LED L-864 lights are preferred due to reduced maintenance and longer lifespan.

L-864 vs. L-810 Obstruction Lights

L-864 and L-810 obstruction lights are often used together as part of a complete obstruction lighting system.

In FAA red obstruction lighting systems, L-864 lights provide the primary flashing signal, while L-810 lights provide additional steady illumination at lower levels.

When Should You Use L-864 Lights?

Choosing between L-864 and L-810 obstruction lights depends primarily on structure height and FAA lighting requirements.

• Use L-864 lights on structures over 200 feet AGL
• Use as the primary flashing beacon at the highest point of the structure
• Use together with L-810 lights when intermediate lighting levels are required

In many FAA-compliant systems, L-864 and L-810 lights are used together to provide complete nighttime obstruction marking.

Where Are L-864 Lights Installed?

L-864 obstruction lights are commonly installed in locations such as:

• At the top of towers and structures
• At the highest points requiring obstruction marking
• On wind turbine nacelles and other tall installations specified by FAA lighting requirements

Proper fixture placement depends on the structure height, configuration, and applicable FAA guidance.

How to Choose the Right L-864 Light

When selecting an FAA L-864 obstruction light, consider the following factors:

• LED or incandescent design
• Voltage requirements
• Environmental conditions
• Flash synchronization requirements
• FAA compliance and certification

Choosing an appropriate, FAA-compliant fixture helps support visibility, reliability, and long-term performance.

Frequently Asked Questions

What FAA document defines L-864 obstruction lighting requirements?

L-864 obstruction lighting is defined in FAA Advisory Circular AC 70/7460-1, which outlines marking and lighting requirements for structures that may affect navigable airspace.

What is an L-864 obstruction light used for?

L-864 lights are used to mark tall structures at night and improve visibility for aircraft.

Is an L-864 light high intensity?

No. L-864 is a medium-intensity flashing red light. High-intensity systems use different FAA light types.

Do L-864 lights flash?

Yes. L-864 lights are flashing red obstruction lights.

What is the flash rate of an L-864 obstruction light?

L-864 obstruction lights flash at 30 flashes per minute (± 3 fpm) in FAA red obstruction lighting systems.

Are L-864 lights used with L-810 lights?

Yes. They are commonly used together in FAA red obstruction lighting systems.

Final Thoughts

FAA L-864 obstruction lights are a critical component of aviation safety systems used to mark tall structures. When combined with L-810 lights, they provide a complete and effective obstruction lighting solution.