Sorry to mention this AGAIN but it all points to the guy not realising.
I imagine that the engineers onboard, if they were irish, work for either Airlingus or i think there is a big-jet maint. company in shannon airport.
So IF this was a charter flight and the pilot and passengers realised what was happening then they would have demanded he landed at nearby shannon. Their may have been 1 mad person on that plane but I doubt 4.
Sorry my little fellow investigators but everything points to him not realising. Bet he'd rather no one realised the circumstances when he landed in Jersey.