The U.S. government chartered the plane to fly out diplomats from the U.S. Consulate in Wuhan, where the latest coronavirus outbreak started, and other U.S. citizens. The plane will make a refueling stop in Alaska before flying on to Southern California, the U.S. Embassy in China has said.
Tuesday night, it was announced that the plane would land at March Air Reserve Base in California's Riverside County instead of at Ontario International Airport in neighboring San Bernardino County.
Curt Hagman, an Ontario airport commissioner, said the Centers for Disease Control announced the diversion.
"We were prepared but the State Department decided to switch the flight" to the airbase, Hagman said.
Wuhan is the epicenter of a new virus that has sickened thousands and killed more than 100 and the official said Tuesday that the plane left the city before dawn Wednesday, China time. The official spoke on condition of anonymity because the official was not authorized to speak publicly.
When the plane arrives in Anchorage, Alaska, passengers will clear customs and go through the Centers for Disease Control screening.
"Then they will put them back on the plane and then send them on to their final destination," said Jim Szczesniak, manager of the Ted Stevens Anchorage International Airport. He didn't know how long it would take beyond "hours."
The passengers are being isolated in the airport's international terminal, which lies mostly dormant in the winter months.
Szczesniak stressed the terminal is not connected to the larger and heavily used domestic flights terminal, and each has separate ventilation systems.
The lobby in the international terminal was nearly empty Tuesday afternoon, and an airport employee was seen jogging through though the facility that has closed counters for companies like Korean Air, China Airlines and Asiana Airlines. There are two businesses operating at either end of the ticket coutners, a 4x4 rental agency and a satellite office of the Alaska Division of Motor Vehicles.
Because the terminal is only active in the summer, it allows the airport to practice situations such as this one.
"In the winter time, we have the ability and the luxury of not having any passenger traffic over there, so it's a perfect area for us to handle this kind of flight," he said.
Officials at the Ontario airport 35 miles (56 kilometers) east of Los Angeles had been readying facilities to receive and screen the repatriates and temporarily house them for up to two weeks — if the CDC determined that is necessary, said David Wert, spokesman for the county of San Bernardino.
Ontario International Airport was designated about a decade ago by the U.S. government to receive repatriated Americans in case of an emergency overseas but it would have been the first time the facility was used for the purpose, Wert said.
Symptoms of the virus include fever, cough, and in more severe cases shortness of breath or pneumonia.
China has cut off access to Wuhan and 16 other cities in Hubei province to prevent people from leaving and spreading the virus further. In addition to the United States, countries including Japan and South Korea have also planned evacuations.