FRH ARE NOT a prohibited item WHEN THEY ARE CONTAINED WITHIN A SEALED MRE BAG. They are allowed packed in your "checked" luggage as well as your carry-on luggage.
If they are carried any other way (individually or in shrink wrapped multi packs) they are then considered a Hazardous Material and will not be allowed on the aircraft.
If any TSA Officer gives you any problem while you are transporting said FRH correctly, kindly (and politely ---at all times---) ask to speak to their Supervisor. Politley (there's that word again!) remind the Supervisor that TSA's own SOP clearly states that the heater can travel if it is indeed contained within the sealed MRE bag. If the Supervisor doesn't give you the satisfaction you deserve, ask for their name, badge number, and a point of contact phone number for TSA Washington Headquarters, and let it be know that you will be reporting them for there failure and refusal to follow their own Standard Operating Procedures (this will really get their attention). Then, if you have enough time before your flight, tell the Supervisor that you want to speak with the airport's Screening Manager. At this point, be prepared to see everyone running for cover! TSA management absolutely, positively, HATES "customer" complaints.
And I want to stress this point again: BE POLITE. The individual Officers are allowed a great deal of personal judgement, so kill `em with kindness.
One more thing I'd like to point out: If you are tavelling on a smaller "regional" airline, that individual airline may have their own internal policy regarding carriage of anything. If THEIR policy says "no fly", then there is nothing the Federal Government can do for you ---- you'll have to abide by the individual airline's internal policies. If you do decide to call an airline ahead of your travel for clarification of any of their policies, ask to speak to a Supervisor or Manager. I can't tell you how many times I've run across travelers incountering problems because they received bogus or incorrect information from talking "with someone" on the phone.
I hope this clears up everyones questions. If not, I'll be glad to respond to anything further you may be "fuzzy" on.
`rats