Which actions are recommended preflight for GNSS based instrument approaches?

Which actions are recommended preflight for GNSS based instrument approaches?

• A. RAIM check only
• B. Check NANU only
• C. All of the above
• D. SBAS availability only

Answer: (C)

When preparing for a GNSS-based instrument approach, you need to verify three aspects of the navigation system: integrity, status, and augmentation availability. Start with a RAIM check to confirm there are enough fault-free satellites to guarantee integrity for the planned route and approach. If RAIM cannot be assured for the required time, you don’t have a reliable basis to fly a GNSS approach. Next, review NANU notices to learn about any planned or unscheduled GPS outages or satellite maintenance that could affect signal availability or accuracy during your flight. This helps you avoid surprises and adjust your plan if needed. Finally, check SBAS availability because, if you’re using SBAS-enabled guidance (such as LPV), you need to know whether the augmentation service is available along your approach to determine which minima you can fly. Considering these three elements together ensures you’re aware of the GNSS system’s integrity, current or upcoming outages, and augmentation service status, which is why all three checks are recommended.

When preparing for a GNSS-based instrument approach, you need to verify three aspects of the navigation system: integrity, status, and augmentation availability. Start with a RAIM check to confirm there are enough fault-free satellites to guarantee integrity for the planned route and approach. If RAIM cannot be assured for the required time, you don’t have a reliable basis to fly a GNSS approach. Next, review NANU notices to learn about any planned or unscheduled GPS outages or satellite maintenance that could affect signal availability or accuracy during your flight. This helps you avoid surprises and adjust your plan if needed. Finally, check SBAS availability because, if you’re using SBAS-enabled guidance (such as LPV), you need to know whether the augmentation service is available along your approach to determine which minima you can fly. Considering these three elements together ensures you’re aware of the GNSS system’s integrity, current or upcoming outages, and augmentation service status, which is why all three checks are recommended.