The PLB will provide a position accurate to within how many NM within how many minutes?

The PLB will provide a position accurate to within how many NM within how many minutes?

• A. 3 NM within 90 minutes
• B. 5 NM within 60 minutes
• C. 1 NM within 30 minutes
• D. 10 NM within 180 minutes

Answer: (A)

A PLB’s reported position comes from the satellite system that detects distress signals and then computes where the beacon is. If the beacon doesn’t have built-in GPS, the system relies on signals received by multiple satellites and uses Doppler shifts and timing data to triangulate the origin. That process takes time to accumulate enough data and for ground processing to produce a reliable fix, typically resulting in an accuracy of about 3 nautical miles and a time frame of roughly 90 minutes before a dependable position is available. Modern GPS-enabled PLBs can provide much more precise locations almost immediately, but the standard figure used in many tests reflects the non-GPS case, hence 3 NM within 90 minutes.

A PLB’s reported position comes from the satellite system that detects distress signals and then computes where the beacon is. If the beacon doesn’t have built-in GPS, the system relies on signals received by multiple satellites and uses Doppler shifts and timing data to triangulate the origin. That process takes time to accumulate enough data and for ground processing to produce a reliable fix, typically resulting in an accuracy of about 3 nautical miles and a time frame of roughly 90 minutes before a dependable position is available. Modern GPS-enabled PLBs can provide much more precise locations almost immediately, but the standard figure used in many tests reflects the non-GPS case, hence 3 NM within 90 minutes.