Yes you're kinda of right there (without going into the minutiae technicalities!) however in order for that kind of approach to be undertaken the runway needs to be certified for Cat II/III operations as does the aircraft and the crew trained to undertake these kind of approaches. Theres a lot of clues in this thread to suggest what the situation may have been with regards to those parameters.
Going to an airfield with better conditions/visibility? Yes, that would have been a good option as their legal fuel requirement would have included a divert to a suitable alternate. However, most pilots here are asking why they DIDNT do that...
...one of the options is a CFIT: Controlled Flight Into Terrain - i.e. the crew flew a fully serviceable/working aircraft into land. Or they had a critical failure which neccessitated them making the approach into Cork only and were unable to get the aircraft down safely due to the failure.
Dont mean to teach you how to suck eggs and hope this helps...
