What is an Omnidirectional Approach Lighting System (ODALS), and why is it being replaced in many locations?

• A. A basic approach lighting system visible from all directions; being replaced by MALSR/ALS for better approach cues.
• B. A radar navigation system; replaced by GPS
• C. A wind measurement system; replaced by LIDAR
• D. A communications protocol; replaced by digital

Answer: (A)

ODALS is a simple approach lighting setup that uses omnidirectional lights placed at the approach end of the runway to give a pilot a general cue of the runway environment from any direction. It helps you know you’re near the runway, but it doesn’t provide a strong, continuous guide toward the extended runway centerline or a reliable glide-path cue, especially in poor visibility.

Many locations replace ODALS with MALSR or other ALS because these systems deliver significantly clearer and more extensive guidance on the approach. They add more lights along the approach path, including sequencing flashers and alignment features that highlight the centerline and distance to the runway. This produces better situational awareness and safer landings in low-visibility conditions, aligning with modern standards and performance expectations.