Just for the record the a/c which landed at Kerry instead of Derry belonged to Eirjet operating a Ryanair flight (ie not actually a Ryanair a/c, crew etc).
Kerry rather than Derry would have been a spectacular navigational error. Considering one airport is in the the North and the other in the South West of Ireland!
I believe the airfield in question was the disused Ballykelly and it was a wet leased Eirjet A320.
Almost as bad as the RYR pilot who landed on a taxiway a few years back.
This was Cagliari I think. Parallel runway system with one runway closed and utilised as a taxiway. You had to make an approach to the closed runway and sidestep. I guess that never happened.