I have just done a quick trawl of schedules from other UK airports to some of the same Greek airports served by Olympic from BHX and it would appear that they make extensive use of Jet2 (from LBA, EMA, MAN, GLA etc), EZY (LPL, BRS, NCL etc) as well as TCX and TOM. Cannot see so far Small Planet being offered from any other UK airport to Greece by Olympic.
BHX does not have a particularly strong 'scheduled no frills' offering to Greek island destinations, ZB only serves HER? Perhaps this is why they have to sub contract flights to a random East European airline as there simply isn't the capacity needed available. Better that than Olympic not bother to offer flights from BHX at all! Looking at the schedule there are no night flights planned which means that any delays during the day could be soaked up whilst the a/c is on the ground overnight (barring of course major tech faults
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