U.S. safety official says unclear when 787 will fly again

WASHINGTON, Jan 18 (Reuters) - U.S. Transportation Secretary Ray LaHood said on Friday that the Boeing Co 787 Dreamliner jet will not fly again until authorities are "1,000 percent sure" it is safe.

LaHood said he could not predict when the 787 would be authorized to resume flights.

The U.S. Federal Aviation Administration on Wednesday temporarily grounded the 787 after a second incident involving battery failures caused one of the Dreamliner passenger jets to make an emergency landing in Japan.

LaHood said safety authorities are closely investigating the jet's lithium-ion batteries, which pack more energy and are faster to recharge but which are potentially more volatile.

"The reason that we grounded it is because we did further consultation with Boeing and there was another incident," LaHood told reporters. "So those planes aren't flying now until we really have a chance to examine the batteries ... That seems to be where the problem is."