Flight Heathrow Airport departs from London Heathrow Airport at 19:10 and arrives at Ho Chi Minh City Tan Son Nhat International Airport at 13:55.
The flighttime is about 12h 45m. The distance travelled ("as the bird flies"): 11454 Km. So the average speed is roughly 898 Km.
There is an 6 hour time difference between London and Ho Chi Minh City