Look to the skies this week in Switzerland and you'll see the heavens are cluttered with private jets.

Billionaires and world leaders from across the globe are flying en masse to the annual World Economic Forum in Davos, Switzerland -- and they insist on traveling in style.

Roughly 1,700 private flights are expected over the course of the week, which is twice as many as normal, according to WINGX Advance, a tracking firm. Traffic is expected to rise 5% compared to last year's event.

Private jet companies have warned clients to plan ahead, as securing spots for landing, take-off and parking can become a logistical nightmare.

"Because last year was so busy, private jet customers know ... that they have to book in advance," said Adam Twidell, CEO of the online jet booking company, PrivateFly. His firm helped clients secure about 20 flights for the event, which starts Wednesday.

The main Zurich airport handles two-thirds of private jet travel for Davos-bound attendees, and a spokesperson said airport traffic surges by roughly 10% during this period.

Zurich airport authorities have reserved roughly 60 parking spots exclusively for Davos-related jet traffic, but it hasn't been enough. All the spots were booked well in advance.

For the first time, the Swiss Armed Forces opened up its Dübendorf military airport to private jet passengers, and many top world leaders are expected to go through this base.

Other popular airports include St. Gallen-Altenrhein and Engadin, though industry insiders said they are sometimes avoided due to regular weather-related disruptions.

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Demand for helicopters also skyrockets during Davos.

On average, the Zurich airport handles five helicopter flights per day. But when the Davos event was on last year, helicopter traffic surged to 54 flights on a single busy day.

Nearly 200 helicopter flights went through the Zurich airport during the last Davos event. Those helicopters carried 500 passengers, which is mind-boggling considering the event only hosts 2,500 attendees.

Private jet company NetJets forecasts that it will operate about 80 flights in and out of the region over the week, up 4% compared to last year.

Meanwhile, another private jet company, VistaJet, expects bookings for Davos travel will roughly double compared to last year, up to about 20 flights.

VistaJet charges between $10,000 and $15,000 per hour to use its planes. Founder Thomas Flohr said customers that book a long-haul journey to Davos can get a helicopter ride for free.