Excerpts from “Lithium Battery Shipments On Passenger Planes ‘An Unacceptable Risk,’ Say Aircraft Makers,” by Suman Varandani, 10 March 2015 International Business Times:
“Aircraft makers and pilot unions are calling for a ban on the transport of lithium battery shipments aboard passenger planes following fears of fires that could prove difficult for aircraft fire protection systems to contain. An industry paper obtained by The Associated Press (AP) cited recent tests conducted by the Federal Aviation Administration (FAA) that showed overheating of the batteries could result in explosions.”
“The FAA tests revealed that batteries emit explosive gases when overheated, and that aircraft fire protection systems ‘are unable to suppress or extinguish a fire involving significant quantities of lithium batteries, resulting in reduced time available for safe flight and landing of an aircraft to a diversion airport,’ according to AP. ‘Therefore, continuing to allow the carriage of lithium batteries within today’s transport category aircraft cargo compartments is an unacceptable risk to the air transport industry.'”
Note that charging of the lithium batteries is not required to initiate a fire; a fire can start with the batteries sitting unconnected in their shipping containers. Triggers can include a manufacturing fault (short) in a single battery cell, a short caused by mechanical puncture during rough handling or travel, shorted terminals due to improper packaging, external overheating, or battery gas emissions that can be ignited by electrostatic discharge.
Update 3-21-15: I guess the word is spreading about lithium batteries and aircraft safety. A reader sent in this pix of a warning label that was on his recently purchased lithium batteries: