Board Thread:Game Updates/@comment-1820055-20150808000124/@comment-4125495-20150810132910

Aircraft SLOTS (not the aircraft themselves) receives experience from all sorts of combat (including recon). A squad of highly-experienced aircrafts will have better combat power as well as recon ability(a system from Spring 2014 that if the recons success, bombers will have better hit rates, didn't find the translation of this term).

Aircraft slot experience rises for each battle fought, and lowers when facing large losses, resets to zero when the slot is completely eliminated. (Not possible to be even lower than before the update) The recon ability you're talking about is Contact: http://kancolle.wikia.com/wiki/Combat#Contact

I really hope this slot training thing doesn't happen in PVP. Will really suck to get an unlucky AACI from an Akizuki or Maya or similar high-AA ship and lose the slots (I've seen this happen with CVLs)