UPS and FedEx have grounded their MD-11 cargo planes, following a crash at an airport in Louisville, Kentucky, that killed three pilots and 11 other people who were on the ground.

The New York Times reports that Boeing — which bought the company that manufactures the plane in 1997 — recommended that companies ground their MD-11s on November 7, "while additional engineering analysis is performed." The Federal Aviation Administration released an emergency airworthiness directive the following day, effectively grounding all MD-11 cargo planes pending a comprehensive inspection.

During the November 4 crash in Kentucky, the left engine detached from the wing of an MD-11 operated by UPS shortly after takeoff, before the plane crashed on the tarmac and exploded. The FAA has since determined that the issue that led to the detached engine "is likely to exist or develop in other products of the same type design," and could lead to further safety issues down the road if it's not addressed. 

MD-11 cargo planes account for roughly 9% of UPS's fleet, as well as 4% of FedEx's. There are an estimated 70 MD-11s in service across all cargo carriers.