Rumours it will be increased versus the current planned 4 weekly winter flights for next Summer too one could only assume a daily service, well thats being hopefull.. as regards Frankfurt it's very possible, looking at the Aer Lingus schedule its hard to find out where they could fit in Brussels at 4 weekly if they wanted to continue to current level of service of 4 weekly beyond the winter they would have to reduce or cut flights as all aircraft are worked all day for the Summer schedule, maybe that 5 a/c
will finally arrive now that's being optimistic.
There have been rumours of EI looking for slots for a 5th ORK-LHR rotation and 4th SNN-LHR;
so if a 5th aircraft was added for the summer, and operated 2 daily LHR (ORK-LHR-SNN-LHR-ORK), 3x weekly BRU, a possible 4x weekly FRA, and maybe some additional frequencies elsewhere, there could be a case for a 5th winter aircraft/ 4th Winter aircraft.