Two important points:
1. Lithium batteries are light in weight, small in dimension and ubiquitous in the electronic technology that is a staple of air cargo.
Unfortunately, two situations push against each other. The non-transportation lay person views them as distinct from “real” hazardous materials – the nasty chemicals that one would expect to require adherence to the Hazardous Materials Regulations.
But the pilots and professional hazardous materials shipping experts associate lithium batteries with powerful combustion events that have reputedly already created real damage to aircraft.
Given their combustibility, lithium batteries present a genuine danger in a setting (aviation) where shipment by air is commercially compelling.
2. According to PHMSA and FAA rules pre-dating concern with lithium batteries, shippers and carriers have historically enjoyed a choice on domestic airline flights: Comply with the U.S. Hazardous Materials Regulations or opt to comply with ICAO rules.
For some in the context of movement of lithium batteries by air, this danger forces a “re-think” of the old dual regulation framework – at least as to this sort of freight.