Billionaire entrepreneur Richard Branson started his airline Virgin Atlantic in 1984 when his flight from Puerto Rico to the Virgin Islands was cancelled.

Rather than waiting for the next available flight, "I hired a plane, borrowed a blackboard and as a joke, I wrote 'Virgin Airlines' on the top of the blackboard, '$39 one way to BVI,'" he says in a video by HP Matter. "I went out to round up all the passengers who had been bumped and I filled up my first plane."

Three decades after after its launch, Virgin Atlantic is the second-largest UK carrier. "But it hasn't always been easy ... during those 33 years," the founder writes in a letter to his employees.

Most notably, when Branson's airline was trying to establish itself in the 1990s, British Airways ran what became known as the "dirty tricks" campaign.

"We had about four planes flying, and [British Airways] went to extraordinary lengths to put us out of business," recalls Branson on an episode of NPR's "How I Built This" podcast. "They had a team of people illegally accessing our computer information and ringing up our passengers and pretending that they were from Virgin, telling them that flights were cancelled and switching them onto BA."