Optimizing Nighttime Navigation: Red vs White Cockpit Lighting

A Tragic Incident in the Houston Ship Channel: Lessons for Aviation Safety

A dredge worker tragically drowned in the Houston Ship Channel when the tug boat he was riding collided with an inbound barge. The tug’s Captain claimed he saw nothing until just before the impact. It’s suspected that the loss of night vision—a critical issue also seen in the aviation industry—may have significantly reduced his ability to detect the inbound towboat and barges.

The Importance of Night Vision in Aviation Safety

Preserving night vision has long been a concern in the aviation industry. Bright cockpit lights can greatly reduce night vision sensitivity, which is crucial for pilots. Traditionally, dim red lighting provided enough light to read charts and equipment while maintaining good night vision. However, with the advent of computerized navigation equipment, red light is no longer the best choice. Instead, low-level white light is now considered better for preserving night vision and aviation safety.

The Debate Over Red vs. White Cockpit Lighting

The debate over red versus white cockpit lighting has been ongoing for years. Red lighting is preferred because it improves dark adaptation, allowing pilots to see better outside the aircraft at night. However, studies have shown that even low levels of white light can impair night vision, while red light helps maintain it. Pilots exposed to red light regain their ability to see faint objects faster and achieve complete dark adaptation sooner than those exposed to white light. At low levels of instrument lighting, the benefits of red light for dark adaptation are minimal and can be easily lost.

Understanding Night Vision for Mariners and Aviators

Night vision is not just about seeing in the dark; it’s about how our eyes adjust to different light levels. During the day, we see using cones, which allow us to perceive colour and fine details. At night, rods take over, being much more sensitive to light but limited to black-and-white vision with less detail.

For mariners and aviators, this creates a challenge: rod vision is crucial for seeing in the dark, but cone vision is needed to read charts and screens. Aviation safety and nighttime navigation require a balance between these two.

The Traditional Fix: Red Light in Cockpit Lighting

Red light was traditionally used because it’s less disruptive to rod vision while providing enough light to read. This makes it a popular choice in cockpit lighting to maintain night vision.

A Better Solution: Low-Level White Light

Today, low-level white light is considered a better option. It provides enough light to read charts without severely affecting night vision, thus enhancing aviation safety. White light helps maintain color vision. It is easier on the eyes, making it a better choice for pilots and mariners.

Conclusion: Practical Tips for Nighttime Aviation

Pilots flying visual approaches at night must identify dimly lit objects outside the aircraft. Turning the cockpit dome light OFF and using low settings for instrument and display lights is advisable. For approaches that rely on instruments, a dim cockpit dome light strikes a better balance between external and internal scans.

Remember, turning off or switching to white lights for reading can affect night vision. A well-informed pilot will choose the best lighting settings based on the environment and type of approach. When flying modern glass cockpit aircraft, keeping the cockpit dome light at DIM instead of OFF helps differentiate colours more distinctly, which is crucial for aviation safety.

The FAA design requirements mandate lighting that doesn’t impair crew performance, underscoring the importance of choosing the proper cockpit lighting.

For more insights on safety, check out my previous blogs:

• The Science Behind Fire Engine Color: Red vs. Lime Yellow
• How the Brain Processes Certain Shapes and Colors Faster: Runway Incursion Prevention

Sources:

• Night Vision and Nighttime Lighting for Mariners, A. Rothblum and D. Wyatt
• A Literature Review of Cockpit Lighting, Alan M. Poston