It's one of the world's most-loved airlines but it's about to vanish forever.

Consistently credited as being one of the US's favourite airlines, Virgin America is set to take its final flight today before it is taken over by Alaska Air as part of a US$2.6 billion ($3.6b) deal.

The two final flights will be Virgin America Flight 1182 which is scheduled to depart San Francisco at 9.30pm, and Virgin America Flight 1948 is due to fly to Los Angeles at 9.32 pm local time.

"We're planning to delight our guests flying on these last two flights with a few surprises," Alaska Airlines said. It's believed a special in-flight safety video performance will be among them.

"We'll be having a get-together in the gate area before the flight," frequent flyer Nate Vallier, who owns an airline IT company, told USA Today.

"We'll have posters, memorabilia and other swag to hand out and, after the flight, we'll be gathering in the Alaska Airlines lounge in LAX to toast to the sunset of the Virgin America brand."

By morning, all check-in counters, kiosks, signs and gate areas branded as Virgin America will vanish from 29 airports around the US and Mexico. The livery and planes will go at a later date.

Usually, passengers love to hate airlines, but not Virgin — the airline had a 7/10 rating on Skytrax and was famous for its safety video.

Dismayed travellers have flooded social media to pay tribute to the carrier.