Aviation Electronics is AT. Aviation Electrician is AE.
When I was in you had to be an E-3 for a minimum of one year before you could take the petty officer exam. Plus you had to have 2 years remaining to sew on the crow if you passed. I cross rated from AEAN to CECN and had to start counting time all over. My score on the CE3 exam was PNA, passed but not advanced, because I had less than two years left on my enlistment.
My mistake, they do not have planes on submarines.