All 50 of the Boeing 787s in use around the world remain grounded after an ANA flight on Jan. 16 made an emergency landing in Japan when its main battery overheated.

NPR: US Regulator Asks Boeing For Full Battery History

It comes after an All Nippon Airways (ANA) 787 had to make an emergency landing due to a battery malfunction.

BBC: Dreamliner: Japan and US probe battery maker

In the most serious incident so far, an All Nippon Airlines (ANA) 787 with 129 people aboard made an emergency landing after a battery alarm Wednesday morning.

CNN: U.S., Japan ground Dreamliners over fire risk