When should one-setting taxiway lights be used during the day?

• A. When visibility is less than 1 mile
• B. When visibility is greater than 2 miles
• C. At all times
• D. When operating with IFR conditions

Answer: (A)

One-setting taxiway lights should be used during the day specifically when visibility is less than 1 mile. This recommendation is based on the need to enhance the visibility of taxiways for pilots during adverse weather conditions, such as fog, rain, or snow, where reduced visibility may hinder their ability to see the taxiway clearly.

The use of these lights in low-visibility conditions helps ensure that pilots can navigate safely on the ground, reducing the likelihood of runway incursions or other mishaps. During normal visibility conditions, particularly when visibility exceeds 2 miles, the one-setting lights may not be necessary as the ambient light levels are sufficient for pilots to see the taxiway markings.

In contrast, having the one-setting lights on at all times may not be advisable, as it can lead to light pollution or distract pilots during clear weather conditions. Likewise, using these lights solely under IFR (Instrument Flight Rules) situations may not comprehensively address the visibility challenges that can arise in various flying conditions, as IFR typically applies to specific weather conditions and not solely to ground operations.