I dont know for sure, but I asked a flight instructor. I asked him if there are limits on how airline planes are flown and he told me that there's a lower altitude limit where you are not allowed to fly below a certain altitude for safety of those on ground and in maneuvering they normally have a limit of 45 degree unless there's emergency or if its necessary etc....Although he had never flown jets, only medium/small turboprops, I think he was right. Cuz using a maximum of 15 degree bank angle its not easy to land the plane at most airports due to traffic. Apart from that, in most flights that i have been in, they turned the plane alot more than 15 degrees on approach to runway.
What u may be talking about could be autopilot bank angle limit....
