Laptops are the best thing that ever happened to airline travel. They enable you to catch up on your work, play games or watch a movie while you are traveling.
Better still, many airlines are now installing costly equipment that enables you to access the Internet during flights. Most of these systems use your laptop's built-in Wi-Fi to connect.
Unfortunately, this laptops-in-the-sky nirvana probably won't last. The problem: Laptop batteries can explode catastrophically. It's happened before, and it will happen again. It's only a matter of time before it happens in-flight.
The FAA forbids you to use your iPod during takeoff - do you think it won't ban laptop batteries?
What's So Bad About Laptop Fires?
Laptop batteries are typically plastic and metal containers that contain somewhere between six and nine individual lithium-ion cells, which look a little like AA batteries. If any of these gets too hot - around 350 degrees for legitimate, noncounterfeit batteries - they can leak flammable liquid, then explode, causing a chain reaction through the rest of the cells (a process called thermal runaway).
The temperature increases and quickly melts a hole in the laptop. As additional cells explode, flaming, poisonous liquid can be thrown several feet in any direction. These explosions and flames are accompanied by acrid, toxic smoke.
The reaction on a crowded airplane to multiple explosions, flames and toxic smoke could easily be panic. People would get up out of their seats and move down the aisles, blocking the path of flight attendants trying to extinguish the flames with on-board extinguishers. The rush of passengers to the front or back of the plane could affect the pilots' weight-and-balance calculations. And the FAA itself admits that airline crews are ill-prepared to handle battery fires in-flight.
Another risk is that terrorists could board a plane with a large number of laptop batteries, both in laptops and in laptop bags as "spares." During flight, they could combine all laptop batteries into a single unit, then heat them up to create explosions, fire, panic and, possibly, damage to the airplane.
What Would the Ban Look Like?
New rules came into effect Jan. 1 that ban spare laptop batteries in checked luggage. Batteries actually installed inside devices are allowed, and most spare batteries in your carry-on are fine, too. But carry-on batteries are now governed by a complicated new set of rules.
You can carry batteries with 8 grams of lithium or less in your carry-on luggage, but they must be carried in plastic bags. Cell phone, PDA and other gadget batteries, plus most laptop batteries, contain less than 8 grams of lithium.
You're now limited to a maximum of two batteries with between 8 and 25 grams of lithium in them. The most common batteries in this category are "extended life" laptop batteries, but also batteries used in larger devices like projectors. If you carry on three such batteries, security will take one of them away. None of these rules would prevent the kinds of standard laptop battery fires I linked to above, especially since batteries inside laptops are still allowed.
Laptop fires are more likely with counterfeit or faulty batteries. The airlines will never be able to check the legitimacy or safety of batteries, so any ban would apply to all batteries regardless of quality.
It seems to me that batteries installed in laptops pose the greatest risk. If you close your running laptop, but it doesn't go into sleep mode as it's supposed to, it's likely to get very hot inside your insulated laptop bag.
Another risk is multiple batteries stowed together, because a chain-reaction explosion gets hotter, more dangerous and more difficult to extinguish as additional cells and additional batteries ignite.
When or if a laptop battery ever catches fire in-flight, we can expect new rules. I think the most likely future FAA rule is that laptop batteries will not be allowed inside laptops, but carried only in plastic bags and never stored with other batteries. Although this is far less catastrophic than total battery bans on all flights, it would ruin the Wi-Fi laptop nirvana I described.