FiSe,
I would say they spelt "Aer Corps" incorrectly, just because it is from a government department does not mean the spelling is right.
A civil servant from a department other than the DOD probably wouldn't have a clue as to the proper title of the Air Corps, hence the all too common spelling mistake.
BTW, the first wave of aircraft goes past O'Connell Street @ 12.30.
Regards,
Frank.