What to know about transiting through China with Chinese airlines (e.g. China Eastern) when flying to Vietnam?

On China Eastern departures or transfers staff may ask for a return/onward ticket — keep a booking confirmation handy to avoid issues at check-in.

On an international-to-international transfer in Chengdu (same Chinese carrier) there's no need to exit the transit zone — the connection stays airside.

During transit security may ask you to take out your power bank and check it for the CCC certification mark — without it you may run into problems, so bring a CCC-certified power bank.

Bookings on Chinese airlines made through a third-party agent sometimes don't show up on the airline's official website — check status via the booking agent or call the airline directly with the reservation code.