Star Trek: 10 Secrets About The 25th Century Fleet You Need To Know
2. Old But Not Out
A true fan favourite that's seen its fair share of outings is the Akira Class, first seen during the Borg encounter that kicks off events in Star Trek: First Contact.
Designed with a unique "roll on roll off" feature to its shuttle bay, the Akira Class can be seen through Deep Space Nine and Voyager, as well as Lower Decks and Prodigy, before adding eighteen of its number to the Frontier Day fleet.
Even with this class still in service, there are two in the fleet museum at Athan Prime. One is the USS Wersching NCC-63328 named after Borg Queen actress Annie Wersching who sadly passed away between airing of the second and third seasons. The second is the USS Sentinel NCC-68455, previously mentioned in the Deep Space Nine episode Treachery, Faith, and the Great River among the ships that Nog barters with to hasten repairs to the USS Defiant.
The Akira Class by this point will have been in service for around 28 years making it one of the oldest classes to make an appearance in the series. This might be topped, or at least equalled by, the Defiant Class - also listed among the attendees of Frontier Day.