Once you’re in HCMC, it’s a $6 or $7 taxi ride to the airport (take Mai Linh taxis if you don’t want to experience the joys of rigged Vietnamese taxi meters). There are a dozen daily flights that fly the HCMC-Hanoi route, priced as low as $40.Vietnam Airlines tickets is the most reliable but most expensive and they charge extra for one way fares. A better option is Jetstar Vietnam. They’re cheap and while Vietnam expats like to gripe about them, I’ve had pretty good experiences with them.