last week we did a transatlantic flight with the short runway at Halifax being the only one available inside crosswind limits . It has a GPS only approach and RAIM predicted a short outage during our planned diversion window. We elected to use it as we had enough fuel to hold if the outage actually translated to a loss of ANP. I believe Canadian airports are not SBAS and so my question is.....if the outage were significantly longer would we have to plan for a different ERA . Can be tricky as our ETOPS range is being reduced due engine issues. Thanks in advance.