Can I use an extension cord or a power splitter on an airplane? We haven't found any rules from airline regulators that would ban the use of extension cords during flights.

While I am aware that one may not use multi-tap power cords (e.g. extension cords, power strips/surge suppressors) for multiplying electrical outlets, I stumbled across another variety that seems ...

UPS->splitter->wall isn't. edit: in theory, a 15-amp cable would be fine, since no single device in the US is allowed to pull more than 15A from the wall. But get a 20A anyway, just to be safe.