Secretary of State Antony Blinken was forced to switch planes in Switzerland on Wednesday after his plane was grounded due to a critical failure related to an oxygen leak.

Blinken and fellow passengers boarded one of Boeing’s popular 737 commercial jets used by the U.S. military, a Boeing C-40. It differs from the Max 9 airplanes that are being audited for safety problems by the Federal Aviation Administration after a door plug blew off an Alaska Airlines flight in midair more than a week ago.