The TSA says laptops need to go into the hold (from some countries) now FAA says they should not go into the hold. So what is the PAX supposed to do? Leave home without his laptop? Seems like the gov needs to get their message right - people will just stop flying if they cannot actually arrive and do business.

Simple solution... just install a halon system in the cabin

That could solve a lot of problems...

I know you jest...but the crux is, halon doesn't work on Li battery fires. Halon works in conventional fires by displacing oxygen. Lithium batteries are self-oxidizing.

Lithium batteries are popular for one reason: they have the highest energy-density you can get in a battery.

The problem with packing a lot of energy in a small space: regardless of the energy source, this has the potential to be a "bomb." Gas in a can, tritonal in a steel case, Semtex, or Lithium paste in a battery.

The solution really should be what they did with the 787 after ITS Lithium battery fires: they put the battery in a steel containment box. The Litium fire can't breach the box, but it gets hot. The box is thermally isolated to prevent contact fires on the outside.

Personally, I'd like to see a small steel baggage pod for Li-powered devices.

Cargo fires have always worried me. Read the transcript of UPS 6, and you will wonder how politicians can value revenue over life.

Very easily... as long as it's just pilots, who are paid to fly and die.

Once you a have a full hull loss of a large pax jet due to a Li battery fire in cargo, then something will have to give. It will probably be an over-water flight, with drawn-out drama. They'll make a movie about it eventually.

My point exactly....

Ah, so like a magnesium fire?

Technically, no.

Metal fires still need O2 but they burn so hot that they are just hard to put out (also hard to start). In some cases they can be hot enough to cause nearby compounds to break down and provide an oxidizer to support the fire in the absence of air. Oxygen is not the only potential oxidizer, especially if you have enough heat.

Li battery fires actually have two things going on...

The chemical energy stored in the battery is released via a short-circuit, generating a lot of current and therefore a lot of heat. This heat causes anything nearby to burn, including the battery compounds and adjacent cells, which then of course trigger a chain reaction as long as there are more batteries close by.

You can't really extinguish it, you just have to keep it cool while it discharges it's energy.

A large number of batteries (ie commercial shipment) would not be controllable once it gets going. Requirements to ship batteries with a lower state of charge reduce the risk.

I'm splitting hairs here, but it could be extinguished if it were cooled sufficiently. Cool it far enough that the energy dissipation is too low to permit the temperature to increase to the flashpoint of the battery or surrounding materials: no fire.

That said, I know of no airline that carries liquid nitrogen fire extinguishers.

Have to disagree on this. Maybe in a laboratory under perfect conditions with the right resources on hand you could pull this off. However my years of training in hazardous materials specialist leave me saying it would be nearly impossible to fully contain a Li-ion battery fire. Temperature wouldn't stop the reaction to both oxygen and water (even humidity in the air is enough to add to this reaction). The lithium itself is oxidizing on contact with the air, and rapid oxidation=fire. It doesn't need other materials around it to burn. Lithium, sodium, potassium, and all the other ums all react this way. It will continue to react unless you could somehow get it to the negative -100C range, that's pretty hard to maintain. And even at that temp it's going to continue to react, just at a slightly slower rate.

Metal box full of water, throw it in, close the lid and let it burn... sorry about your iTunes songs buddy. The large volume of water would be enough to compensate for the heat. Unfortunately this doesn't work for the cargo hold unless we start transporting blue wales in the hold like some Star Trek IV level stuff. Dang wales and their PEDs...