Flight Changi Airport departs from Singapore Changi Airport at 18:25 and arrives at Ho Chi Minh City Tan Son Nhat International Airport at 19:55.
The flighttime is about 2h 30m. The distance travelled ("as the bird flies"): 405 Km. So the average speed is roughly 162 Km.
There is an 1 hour time difference between Singapore and Ho Chi Minh City