WONSAN-When he booked his tour, Swiss lawyer Rafael Studer hadn't seriously considered the option of jumping out of a Russian-made helicopter at 2,000 meters strapped to a North Korean soldier.

"It wasn't really part of the plan," the 27-year-old admitted after landing his tandem parachute jump at North Korea's first aviation show held in the eastern port city of Wonsan.

The two-day festival was part of efforts by the sanctions-strapped and diplomatically isolated country to boost hard-currency tourism in the Wonsan region.

Coming just weeks after the North conducted its fifth nuclear test, triggering global condemnation and the threat of fresh sanctions, the show drew several hundred foreign aviation enthusiasts who paid for brief flights in Soviet-era aircraft.

So it was that Studer found himself half-hanging out the door of a Mil Mi-8 helicopter, 2,000 metres above the newly-renovated and upgraded Wonsan airport, strapped to a North Korean military parachutist.

"There was a 'what the hell am I doing moment' and then we jumped. Terrifying at first, but then surprisingly enjoyable," he said.

Studer landed gently, unlike Dutch flight instructor Niels Linthout, who landed barefoot - "I lost my flip-flops" - and face down underneath his tandem partner, much to the amusement of the large crowd.

A number of foreign professional skydivers took part in the show, including American Douglas Jaques, a 68-year-old veteran of more than 11,400 jumps.

The US State Department strongly advises US citizens against travelling to North Korea in any capacity, citing a "serious risk of arrest and long-term detention."

In March this year, an American student Otto Warmbier was sentenced to 15 years hard labour for allegedly stealing a propaganda poster from a hotel.

Jacques said the travel advisory had given him "pause for thought" but the prospect of skydiving "in the most exotic location I could think of" had proved too shiny a lure.

"It's like the warning on a drug label," he said of the State Department warning. "They have to cover the worst-case scenario."

Jacques and fellow pro-skydiver Klaus Renz from Germany said the equipment used by the North Korean parachutists was generally high quality.

"The canopy designs are copies, but they're good copies," said Renz. "They seem very well organised."

Later in the day, a tour of air force fighter jets on the airport runway saw North Korean officials jostling for a photo-op with the country's two first women fighter pilots, Rim Sol and Jo Kum-Hyang, as they posed with an ageing MiG-21.

The two women shot to national fame last year when leader Kim Jong-Un dubbed them "flowers of the sky" after watching one of their training sessions.