As the US Department of Transportation proposes stricter rules on the shipments of lithium batteries, a close look at Federal Aviation Administration data finds that midair incidents involving batteries have been both rare and, apart from one catastrophe, relatively benign.

Between March 1991 and September 2009, there have been a total of 109 incidents globally involving batteries that exploded, caught fire, or emitted smoke, according to FAA data (downloadable as a PDF here) collected over the past two decades and analysed by Computerworld.

The incidents resulted in 51 injuries and one death. Many came from a single August 1999 disaster, in which one passenger died, 13 suffered critical injuries, and 14 had minor injuries, after a Taiwanese passenger jet exploded upon landing. An investigation determined that gasoline from a leaky canister carried in an overhead passenger bin ignited sparks from a nearby 12 volt motorcycle battery.

Excluding that horrific disaster, fewer than two documented injuries have been reported per year, all of them minor and most of them involving loading dock workers, and not passengers or in-flight air crew. Fifteen incidents in the last two decades were serious enough to warrant a plane to reroute or perform an emergency landing, according to FAA data.

For instance, in 2008, there were nine battery accidents resulting in two minor injuries. There were 3.3 billion lithium batteries transported in 2008, according to the Portable Rechargeable Battery Association, on 77 million flights, according to the Airports Council International, including 56 million passenger and combination passenger/cargo flights.

Based on that data, one's chances of being on the same flight with someone who suffers a minor injury due to a malfunctioning battery was about one in 28 million in 2008. By comparison, the one year odds of dying from a car accident in the US are one in 6,584, according to the National Safety Council (download PDF).

Other analyses using data visualisation software provided by Tableau Software show that:

  • Laptops were implicated in four accidents (two were Dell laptops, one was an IBM machine).
  • The most common devices implicated were cordless drills and other power tools, which were involved in 10% of accidents (11).
  • Flashlights were the next most common device, involved in five incidents.
  • Lithium and Lithium-ion batteries were involved in 38% of FAA-documented incidents. Large industrial batteries, which are prohibited in carry-on luggage and are already subject to strict packaging regulations worldwide, were involved in 37% of incidents.
  • Lithium battery related incidents were far less common in the U.S. than industrial battery incidents (31% versus 41%), especially compared with the rest of the world (60% Lithium, 20% industrial battery). That can't be credited to a ban enacted in 2008 barring fliers from carrying spare lithium ion batteries in their checked luggage to prevent accidental sparking: 54% of the incidents on US airplanes in the last two years have involved lithium batteries, double the rate (27%) between 1991-2007, before the ban was enacted.

The FAA data, while incomplete, is significant because it provides support, or lack thereof, for proposed new DOT restrictions around the air freight shipment of battery-powered devices, as well as fliers carrying spare alkaline or nickel-metal-hydride batteries in their checked-in luggage.

The DOT proposal is an extension of the 2008 FAA ban against lithium batteries in checked luggage.

The PRBA favors stricter enforcement of existing rules, rather than stricter new rules. The proposed rules would disrupt global supply chains by making US regulations stricter than the rest of the world. That would raise costs for manufacturers and air carriers, which would pass on those higher costs to consumers, especially online buyers, and create unnecessary hassle for fliers, said George Kerchner, executive director of the PRBA.

A source in the airline and carrier industry, who asked not to be named, agreed. "The DOT has significantly underestimated the number of packages that would be affected, and the cost that would be incurred by consumers and industries."

The DOT, FAA and the House committee on Transportation and Infrastructure, however, say the new rules are needed to raise awareness, force businesses and shippers to use stronger packaging, and cut down on the number of accidents.

They are taking public comments on the proposal until mid-March (which can be viewed and commented upon here). The DOT did not return a request for comment, while a spokesman for the House committee declined to comment.

Many of the incidents involved burning or smoking packages that were discovered during the unloading of cargo or passenger planes. Those incidents were categorised by Computerworld as having started onboard the plane, to counteract the obvious observer bias.

Even accounting for that, only about half of the incidents took place in the air, the rest occurring on the ground. Some were caused by worker negligence, such as an April 1999 incident where a dockworker "mishandled one of the two pallets causing lithium batteries to dislodge from their packaging," causing a fire, according to the FAA.

Cargo planes, not passenger jets, were involved in a majority of incidents (60%). Incidents involving shippers such as FedEx and UPS (25% and 12%, respectively) outnumber those involving passenger airliners (United Airlines led the pack with three). However, no airline was listed in almost half of the incidents.