pretty short flights on the hop from Helsinki to Tallinn, about 15mins on an MD80. They seem to codeshare with Finnair, so if you are connecting from Helsinki, there's a good chance you could be on a Finnair plane.
Billings:
Estonian Air do not actually fly to Helsinki, nor have they operated MD-80s; they don't seem to codeshare any more either (I guess they gave it up). The two operators on this short hop are Finnair and Estonia-based Aero Airlines, both of whom use ATR72s (there is also a Helicopter operator and lots of ferries and hydrofoils etc). You can almost see one city from the other. And if Aero look just like Finnair, they are - they are owned by them and use ATRs transferred from the main Finnair fleet, and it seems to just be a way to use cheaper Estonian crews, I fear. They are even "subchartered" by Finnair to do some internal Finnish runs.