Polar Comms - Iridium Backup
Polar Code Chapter 10 communications - Iridium (GMDSS A4) mandatory for Polar Code voyages beyond INMARSAT coverage.
Comms required
INMARSAT A3 OK
Formula, assumptions, and limits
INMARSAT-GEO coverage degrades ≥ 70° latitude; none beyond 76°. Polar Code requires 2-way voice + SAR alerting world-wide. Iridium LEO constellation only option at poles.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| GMDSS sea areas | - | SOLAS IV |