Vietnam Airlines fly to Dong Hoi (VDH) from Ho Chi Minh City (SGN) and Hanoi (HAN)
Jetstar fly from Ho Chi Minh City (SGN)
They don’t fly every day, so it is recommended that you check the flight schedules when planning your itinerary. Booking online can be less costly than booking through your travel agent back home, so take a look before you book.
Once you get to Dong Hoi, you will need a transfer to Phong Nha.