Quote Originally Posted by JeanneOrnitier View Post
I think the only aetheryte accident we know about is when one was destroyed in the war between Sil'dih and Ul'dah, and the entire army teleporting to that one specific one was lost forever in the lifestream (like Y'shtola briefly was in Heavensward).
To be pedantic, that wasn't exactly an accident, but rather enemy action. Specifically, Sil'dih (or at least the faction that would later found Sil'dih) use aetherytes to transport troops right into Ul'dah's bases, and Ul'dah destroyed the aetherytes while the troops were en route. This sequence of events pissed off Sharlayan enough that Sharlayan de-activated the entire aetheryte network of Eorzea until the Belah'dian civil war was resolved.

While that was the one time there was confirmation of such a thing happening, we do see at least one more occasion where there was preparation to do the same: the Ala Mhigan Resistance lookout at Rhalgr's Reach back in Stormblood had orders to destroy the aetheryte there the moment they got word that Garlemald was going to push troops through. The implication was that the XIIth had tried that same tactic before (successfully), regardless of the loss in troops from forcing them through to an unattuned aetheryte.

For that matter, we were almost the victim of being lost in the aetherial sea due to forcing ourselves to an unattuned aetheryte, in pursuit of Iceheart. Moenbryda carefully did not tell us until after the fact that her experimental technique for doing so was not a guaranteed success.