FILE PHOTO: U.S. Senate Judiciary Committee Chairman Lindsey Graham (R-SC), ranking member Senator Dianne Feinstein (D-CA) and Senator Pat Leahy (D-VT) participate as William Barr testifies before a committee hearing on his nomination to be attorney general of the United States on Capitol Hill in Washington, U.S., January 15, 2019. REUTERS/Jonathan Ernst

(Reuters) - Democratic U.S. Senator Dianne Feinstein on Monday urged the U.S. Federal Aviation Administration to ground Boeing’s 737 MAX 8 fleet after two fatal crashes since October.

“Until the cause of the crash is known and it’s clear that similar risks aren’t present in the domestic fleet, I believe all Boeing 737 Max 8 series aircraft operating in the United States should be temporarily grounded,” Feinstein wrote.

The FAA, which told carriers on Monday that the plane is airworthy, and Boeing did not immediately comment. “Continuing to fly an airplane that has been involved in two fatal crashes within just six months presents an unnecessary, potentially life-threatening risk to the traveling public,” Feinstein added.