173 
Process: 
2. Monitoring and execution of the voyage 
Name 
Date 
Created: 
Mathes 
27.2.98 
Data flow: 
Geographical data 
Checked: 
1. Origin 
• The origin of the geographical data used, i.e. the originator or manufacturer, must be 
known. 
2. Validity 
• Geographical data for voyage monitoring and execution must originate from an authorised 
source. 
3. Quality 
• The scale or degree of detailing of geographical data must be in keeping with the tasks 
being fulfilled. 
• The accuracy of geographical data is generally verified by means of certification. Nevertheless, 
the accuracy - particularly with electronic data - should be monitored. 
• The geographical data used must be sufficiently up-to-date. Suitable mechanisms for updating 
the geographical data base must be available. 
• It should be possible to check the plausibility of geographical data with the aid of external 
data sources (eg radar, ship position). 
4. Harmonisation 
• The geodetic datum for the geographical data used must be known. 
• The geodetic datum used must be identical to other geographically related data jointly displayed. 
• Harmonisation with RADAR/ARPA data displayed in superimposed form must be 
monitored. 
5. Criticality 
• When using electronic data, suitable protection mechanisms against the deletion or modification 
of these data should be provided. 
• Suitable back-up mechanisms and redundancies must be present. • 
6. Limit values and alarm facilities 
• Alarm if geographical data used do not originate from an authorised source. 
• Alarm if data are not up-to-date. 
• Alarm if different geodetic data are used. 
7. Representation/display 
• The representation of geographical data must meet the international rules (IHO/IEC). 
• For the purpose of representation, screens with suitable resolution should be used.