5.5 Monitoring of Gross Navigation Errors 5.5.1 Radar stations capable of monitoring the boundaries of the NAT Region collect data on flights within MNPS Airspace, together with that on non-MNPS Airspace flights. The former data provides a direct input into the risk modelling of MNPS Airspace, whilst the latter provides a wider appreciation of navigation in the NAT Region and allows followup action to betaken on a larger sample of flights believed to have experienced navigation errors. 5.5.2 The data collection process comprises two parts a) continuous collection of all deviations of 25 NM or more (i.e. GNEs); and b) collection of data on deviations of between 15 and 25 NM as required. 5.5.3 When a GNE has been detected by the ATS Provider State or has been reported to ATC by the pilot, that ATS Provider unit will, in cooperation with the Operator, investigate its cause. It is important that all agencies react promptly to reports of GNEs. Investigations should be made at once so that consideration can be given to the need for swift remedial action. In order that deviation reports can receive prompt attention, each airline/Operator should nominate a person to be responsible for receiving reports and to initiate investigations the name and full address of this individual should be notified to each relevant ATS administration.