For RNAV approaches, which capability is essential for safety?

For RNAV approaches, which capability is essential for safety?

• A. GNSS integrity
• B. Radar availability
• C. Ground speed indication
• D. Altitude alerting

Answer: (A)

In RNAV approaches, having a reliable navigation solution is only safe if the data behind that solution can be trusted. GNSS integrity is the capability that makes this trust possible by detecting and warning about errors in the satellite navigation data in time to avoid unsafe actions. When the integrity is ensured, the system can confirm that the position, track, and derived guidance are within acceptable limits, which is critical for maintaining the precise lateral and vertical path required to safely reach the runway and to execute any missed approach if needed. Without integrity, even a highly accurate fix could be misleading because unseen faults in satellites, signal blockages, or other anomalies might go undetected. That gap could lead to off-course deviations, incorrect altitude or course guidance, and potential conflicts with terrain or obstacles. Integrity monitoring—such as RAIM or SBAS—provides the safety net that alarms pilots or autopilots when the GNSS data can no longer be trusted, allowing appropriate actions. Radar availability, ground speed indication, and altitude alerting are useful tools in flight operations, but they don’t address the fundamental safety requirement specific to RNAV approaches: the trustworthiness of the navigation solution itself.

In RNAV approaches, having a reliable navigation solution is only safe if the data behind that solution can be trusted. GNSS integrity is the capability that makes this trust possible by detecting and warning about errors in the satellite navigation data in time to avoid unsafe actions. When the integrity is ensured, the system can confirm that the position, track, and derived guidance are within acceptable limits, which is critical for maintaining the precise lateral and vertical path required to safely reach the runway and to execute any missed approach if needed.

Without integrity, even a highly accurate fix could be misleading because unseen faults in satellites, signal blockages, or other anomalies might go undetected. That gap could lead to off-course deviations, incorrect altitude or course guidance, and potential conflicts with terrain or obstacles. Integrity monitoring—such as RAIM or SBAS—provides the safety net that alarms pilots or autopilots when the GNSS data can no longer be trusted, allowing appropriate actions.

Radar availability, ground speed indication, and altitude alerting are useful tools in flight operations, but they don’t address the fundamental safety requirement specific to RNAV approaches: the trustworthiness of the navigation solution itself.