There are some new route requirements for eastbound departures from BIKF/Keflavik and BIRK/Reykjavik. Two new waypoints, PODAR and RAPAX are being introduced from Mar 29 onwards.
Below is the updated version of Iceland AIP ENR 22.214.171.124.3.7 which explains exactly how you should file your flight plans to/from both BIKF and BIRK, and the new routes are highlighted:
To make all this blurb easier to understand, the good folks at Isavia have published some handy graphic presentations of the requirements for eastbound departures from BIKF and BIRK:
If you follow the guidance and flight plan accordingly, you should avoid any nasty last-minute “FPL REJ” messages!