What happens when WAAS signal is lost?

When the WAAS (Wide Area Augmentation System) signal is lost, the GPS receiver's ability to provide precision approaches using WAAS is affected. Specifically, the system will no longer be able to support approach mode based on the augmented signal, which means that the GPS will revert to utilizing only the standard GPS signals. This transition means that it cannot utilize the enhanced accuracy and precision that WAAS provides during an approach, which can lead to a change in available approach capabilities.

The functionality of the GPS in terms of approach and navigation is reliant on WAAS for certain types of precision approaches. Without the WAAS signal, the receiver may notify the pilot of the loss, but it will no longer function in the high-accuracy mode needed for specific instrument approaches that depend on WAAS. Therefore, while the GPS may still be operational for general navigation purposes, it will not display approach mode designed for WAAS, limiting the pilot's ability to conduct precision approaches in that scenario.