Not trying to aruge here, but I highly doubt that MOST would be able to get a completely solid frozen ice pack to the point of the TSA check. Just too much time evolves to keep it solid. Maybe if you had it in a Yeti and got out at the curb with it... ehh.

If someone has successfully done this I sure would like ot hear that story - in detail.

Note: Here in the south everything melts instantly... even in January!