When conducting an IFR flight using a published IAP, how should the minimum visibility be treated if ALS is OTS?

When conducting an IFR flight using a published Instrument Approach Procedure (IAP), the treatment of minimum visibility when the Approach Lighting System (ALS) is Out of Service (OTS) is a critical aspect of maintaining safety. The correct approach is to raise the minimum visibility by half a statute mile. This adjustment is necessary because the ALS enhances pilots' ability to see the runway and improves their visual references during the final stages of the approach.

When the ALS is OTS, pilots lose this additional visual aid, which means they need to rely more heavily on their instruments until they are closer to the runway. Consequently, increasing the minimum visibility by half a statute mile compensates for the lack of guidance that the ALS would typically provide, ensuring that pilots have a greater margin for safely identifying the runway and executing the landing. This adjustment reinforces the importance of adhering to the minimums specified in the IAP to maintain safety during IFR operations.