As other Poster said - there are two carriers who are very incestuously linked - financially, with VietNam Airlines on top.
The country uses a
two-hub system:
HCMC/SaiGon and
Ha Noi with all destinations south of Da Nang going to HCMC/SaiGon and all destinations north of Da Nang going to Ha Noi
EXCEPT Da Nang has flights to both HCMC/SaiGon and Ha noi.
Both carriers are rated US safe and generally employ Foreigner pilots.
VietNam Airlines has a bad habit of cancelling a flight if there are few passengers - with none to minimal advance notice.
Tickets are best bought from Travel Agents with shops (few are IATA rated) or at VN Airlines offices (all over the country).
Flight attendants cute and good service; food services minimal - most flights are around one hour.
External services to Bangkok (~80 minutes) are numerous - Thai and VietNam Airlines are high priced - others (regional) are far better priced with Laos Airlines being the cheapest from Ha Noi.
DON'T FORGET THE DEPARTURE TAX MONEY - USD$ or DONG.
Great info on VietNam (especially the FAQ) at <
www.wompom.ca/vietnam/index.htm >. Checkin at airports One Hour Prior.