An expanded ban on large electronic devices in carry-ons to flights from Europe appears to be on hold for now, but aviation experts in interviews last week warned of the danger of storing those devices, which use lithium-ion batteries, unattended in an airplane's cargo hold. 

Lithium batteries are ideal for personal electronic devices because they are lightweight and have a lot of power. However, lithium is also very reactive, and all that power can cause them to overheat and catch fire or explode.

In the Hot Seat

Aviation safety consultant John Cox spoke about why it is risky to store devices like laptops that use lithium batteries in the cargo holds of commercial aircraft. Read More

While most flight attendants are trained to put out such fires in the cabin, some experts said the extinguishing systems in the cargo hold aren't made to put out lithium-battery fires.

On Wednesday, a San Francisco-New York JetBlue flight was diverted to Grand Rapids, Mich., after a laptop caught fire in an overhead bin. The fire was extinguished before the plane landed, and no passengers or crew were injured.

The Department of Homeland Security (DHS) said earlier this month that it was considering expanding a ban on laptops and tablets to inbound Europe flights but on Tuesday decided not to do so, for now. It is an option that is still on the table, the DHS said.

Laptops and tablets are not allowed in carry-on bags on flights from 10 airports in the Middle East and North Africa.

Aviation analyst Bob Mann of R.W. Mann & Co. said that expanding the ban would "not only be highly disruptive, it is dangerous."

An expanded laptop ban, he said, raises the prospect "for far more flights carrying dangerous loose batteries and devices ... in the cargo compartments, where fire is more difficult to detect and fighting fires is more difficult than in the cabin, than flights carrying armed terrorists."

As for why airlines seem to not be publicly speaking out more forcefully against the proposed ban, Mann said they are "being cowed into 'going along to get along' with the administration."

John Cox, a retired US Airways airline captain who now runs an aviation safety consulting company, Safety Operating Systems, and specializes in in-flight fire issues, said that the DHS has not asked for enough input from the airlines and aviation industry groups.

"The DHS doesn't appear to be listening to very many people, because they are not really including the FAA in these conversations," he said. "They are just saying, 'We have a security concern,' and they are not willing to provide any risk analysis and go through the normal steps that aviation safety goes through when there is a potential to add risk into a flight."

So far, the DHS has not publicly elaborated on the danger of having laptops in carry-ons vs. checked luggage.

"If the risk is so great that [laptops] shouldn't be in the cabin, then my question is, why is it OK for them to be in the cargo hold?" Cox said. "There is an inconsistency here that is clouded under [the information being classified]. I don't need to know how they know this. All I am interested in is the risk and how we're going to mitigate it to an acceptable level."

Mann and Cox both pointed to the loss of two cargo airplanes and crew due to inflight fires that are suspected to have been caused by battery fires.

Laptop fire on JetBlue flight

Pilots of a flight from New York to San Francisco were forced to land in Grand Rapids, Mich., after a fire was started by a lithium battery inside a passenger's laptop. Read More

One was a UPS plane departing Dubai; the other was an Asiana cargo flight that went down off of South Korea. Both Fed-Ex and UPS have revised their policies or banned the commercially packed shipment of lithium-ion batteries by air as a result.

"Given that passengers cannot be presumed to know how to properly pack spare and in-use batteries and devices, this proposed order has very serious safety implications for every flight on which it is imposed that I hope, but doubt, have been factored into the risk equation," Mann said.

But not all experts are concerned. Robert Kostecki, a battery scientist with the Lawrence Berkeley National Laboratory in California, said that while there is a risk of lithium batteries catching fire, it is not a significant one.

"Those lithium battery fires get a lot of publicity, but they are still an extremely rare event," Kostecki said.

"We are surrounded by billions of batteries being built every single year," he said. "If you look at the scale, the number of those batteries, and compare them to how often they fail in a catastrophic way -- those are very rare events in which there is real fire risk."

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