Originally Posted by TGarza

In 2021 AA banned heating pads which plug into the airplane power source. There is no TSA rule banning heating pads in carry on luggage. The pad uses your USB battery with a USB A connection. Avoid the heating pads with proprietary connectors.

I have used the USB heating pad for a couple of years when traveling on AA. The pad will cycle off requiring 1, 2 or 3 squeezes to cycle the pad to the correct heat level.