The NTSB is "probably weeks away" from completing its probe into causes of a battery fire on the Boeing 787 Dreamliner.
"We will talk about special conditions that were put into effect at the time when the Dreamliner was certified," Hersman said at a briefing hosted by the Christian Science Monitor.
"In essence what happens when an aircraft is certified, it basically gets locked into the standards that are in existence at the time. So the question ... is whether or not as time goes on through the life of the aircraft, do they fly with new standards?" Hersman said.
Hersman declined to comment on a report that she was the White House's top choice to be the next transportation secretary, saying she was focused on her current job.
She said the Dreamliner investigation was a priority for the NTSB, where "it's all hands on deck" to find the cause of the battery fire.
Hersman said the NTSB has been looking at the risks of lithium-ion batteries for some time and has recommended strategies to reduce potential hazards.
There will always be advances in technology, but the safety side of that is "to make sure you've done the right risk assessment, that you understand what the failure modes are and that you've mitigated any potential risks", she said.
"I would not want to categorically say that these batteries are not safe. Any new technology, any new design, there are going to be some inherent risks. The important thing is to mitigate them."