A serious malfunction in U.S. Secretary of State Antony Blinken's plane delayed his return to the U.S. as scheduled today. After flying from Davos to Zurich by helicopter and boarding a modified Boeing 737, Blinken and his aides were informed that the plane was not safe for travel due to an unrepairable oxygen leak discovered earlier. A smaller aircraft was sent from Brussels to Zurich to take Blinken back home, while many of his aides and accompanying journalists had to travel to Washington on commercial flights. While issues with planes are not uncommon, today's incident comes at a challenging time for Boeing.