Requirements
The overall maritime requirements are defined in the IMO (International Maritime Organisation) regulation A.915 (22), "Revised maritime policy and requirements for a future Global Navigation Satellite System (GNSS) , January 22nd 2002:
[1] Continuity is not relevant to ocean and coastal navigation
[2] More stringent requirements may be necessary for ships operating above 30 knots
Maritime – Minimum User Requirements for General Navigation | |||||||||
Application | System Level Parameters | Service Level Parameters | |||||||
Absolute Accuracy | Integrity | Availability (% per 30 days) | Continuity (% over 3 hours) [1] | Coverage | Fix interval (s) [2] | ||||
Horizontal (m) | Alert Limit (m) | Time to Alarm (s) | Integrity Risk (per 3 hours) | ||||||
1 | Ocean navigation | 10 | 25 | 10 | 10-5 | 99.8 | N/A | Global | 1 |
2 | Coastal | 10 | 25 | 10 | 10-5 | 99.8 | N/A | Global | 1 |
3 | Port Approach and Restricted Waters | 10 | 25 | 10 | 10-5 | 99.8 | 99.97 | Regional | 1 |
4 | Inland Waterways | 10 | 25 | 10 | 10-5 | 99.8 | 99.97 | Regional | 1 |
[1] Continuity is not relevant to ocean and coastal navigation
[2] More stringent requirements may be necessary for ships operating above 30 knots