At midday on Sunday, hundreds of cars were at the airport to pick up and drop off passengers, causing congestion.
Passengers were instructed on their check-in procedures.
"Despite arriving at the airport quite early, my family and I had to queue up for a long time to check in," said a passenger.
Seats at the airport lounges were full of passengers.
Kim Cuc from Tan Binh District said that it had taken her 15 minutes to find a seat in the lounge.
On Sunday morning, most domestic flights were full.
People had to stand in long queues to board their flights.