Correct me if I'm wrong, but doesn't the TH-57 have an ILS? If so, why the hell doesn't a tactical aircraft (F/A-18) NOT have ILS??
Oh, and while it isn't extremely difficult, it is definitely the most pointless and most involved approaches at NGP. It is the BANE of primary stud I4390 checks here in Corpus:
http://204.108.4.16/d-tpp/0804/00098VDYTY13R.PDF
The Tacan Y isn't any worse than the Tacan A into Rockport. Plus, it's a good way to get "bonus points" on your I4390 if you don't fuck it up.