NPR People: Robert Siegel

The National Transportation Safety Board (NTSB) says it is working "around the clock" to determine what caused battery failures on two Boeing 787s. NTSB Chair Deborah Hersman said it's clear there was a fire and there are indications of a short circuit problem, but the agency still doesn't know what caused a battery to catch fire. Robert Siegel talks with Wendy Kaufman.