Currently they are only looking for 4 aircraft and hope to start services by the end of 2019 which favors the A350-1000 of which they are looking at starting SGN-LAX.
Vietnam is also expected to receive FAA Category 1 status by May 2018
The Skyteam carrier is assessing both the Boeing 777X and Airbus A350-1000 for the 7,098nm Ho Chi Minh City-Los Angeles route, says Vietnam Airlines executive vice president Le Hong Ha.
"The flight time is quite long, more than 16 hours," he says. "The sellable payload is very important to us, so we are studying what aircraft, based on performance, allows us to launch the route by the end of 2019."
The possible acquisition would entail four aircraft. Should the 777X be selected, the aircraft is only likely to be available for Vietnam Airlines in 2021.
https://www.flightglobal.com/news/artic ... -s-444077/