Overhyped private jet startups are falling fast

Phone calls this week to BlackJet, the private jet seat-booking service backed by Ashton Kutcher, Jay Z’s Roc Nation and others, went directly to an answering service.

The West Palm Beach, Fla., company, which was still collecting annual membership fees of $3,000 and up a few weeks ago, closed up shop on May 5 — having burned through more than $24 million in funding.

Executives at Beacon, a second membership jet service that operated between Westchester County and Boston, stopped operating in April.

It charged $2,000 a month for unlimited travel between the two points — but that wasn’t enough to keep it from going through the $8.5 million it had raised.

The two private jet companies learned the hard way that it wasn’t going to be easy to become an Uber-type service for the private jet set.

Both companies offered limited routes to fly — BlackJet Technologies, as it was formally named, flew mostly between New York and the West Coast, South Florida and Las Vegas.

It also didn’t own its own planes — which, at times, limited availability, sources said.

Gotham Air, a luxury helicopter service, also closed its doors recently.

BlackJet, when it started three years ago, had plenty of potential. It launched with the help of Uber co-founder Garrett Camp and counted as investors, in addition to Roc Nation and Kutcher, Will Smith, and tech executive Marc Benioff.

The company confirmed it had ceased operations earlier this month after being in business since 2013.

The fee-based business model was new to the Uber for X — the common term for the on-demand model.

The more common model for the private jet industry is fractional ownership or buying cards for hours of travel.

While these companies have been great at getting press, they haven’t been so fast at advertising their disappearance.

Flier Mark Cochran shared his experience with Gotham Air on its Facebook Page in October 2015, saying: “Calls and e-mails not returned over several weeks. Sadly unable to book.”

Craig Ross, who is founder of Aviation Portfolio, which has a team of 10 analysts advising investors and consumers on the private aviation landscape, told The Post that often times bankruptcies are due to companies that can’t source enough planes and crews to cover their routes.

“They’re too focused on the supply side,” added Ross, describing the effort to sign up as many subscribers as possible at the outset. “We speak to people who lost their money,” Ross said. “There’s a lot of upset people out there.”

The key to staying alive is owning technology and not owning planes.

JetSmarter, which earlier this year paid Kim Kardashian West and hubby Kanye’s $10,000 membership to fly their service to attract users, uses a booking engine, while Blade, run by former Warner Music executive Rob Wiesenthal, has a crowd-sourcing technology and sells trips by the seat, sources said.

JetSmarter denies it paid the $10,000 membership fee for Kim Kardashian West and her husband, Kanye West. “[I]n fact, they paid us,” a spokesman for the company said.