Last month, a wealthy Middle East family paid $500,000 to charter a private jet to Europe. The price for the large, Boeing Business Jet wasn't all that unusual in the world of private jetting.
What was unusual, however, was the way the family booked: through an Iphone app.
"We were surprised," said Carol Cork, director of marketing at PrivateFly, the London-based jet charter company that took the Middle East booking. "But for us this was a massive verification of our mobile strategy."
Private jet companies and their wealthy clients are quickly going mobile. While many aviation experts predicted that the rich would never book $500,000 flights (or even $50,000 flights) through their mobile phones, the market is quickly proving them wrong.
PrivateFly said that it expects its app bookings to more than double as a percent sales over the next year to 15 percent. The company said a growing number of its app bookings are from business fliers stranded at airports by canceled or delayed commercial flights.
Cork said that when Heathrow had to close recently, several clients took to their Iphones and booked a private flight. She also said the company is seeing strong app bookings from tech magnates.
(Read More: Top 3 fantasy toys for the super-rich)
"The profile of our app customers is that they are technology entrepreneurs with an interest in the technology, or people that want discretion with their booking," she said.
She said that clients still have to call PrivateFly to complete make the payment, since the sums are so large. But Cork said that for some clients, booking through an app first is "more convenient."
BlackJet, the San Francisco-based charter company, has also built a growing business around jet apps. Rather than booking planes, BlackJet customers book individual seats on private jets. BlackJet Founder and CEO Dean Rotchin said about half of its bookings are now through the company's app.
"These are people who are tech savvy and love the idea that they can book their seat with just 10 taps on their phone," he said.
Jet apps are especially attractive for companies booking seats rather than entire planes, since seats are cheaper and appeal to a much broader market. At BlackJet, customers pay a $2,500 annual membership fee that allows them to download the app, "like Netflix," said Rotchin.
Clients can then book a seat on a private jet. A flight from, say, New York to Florida can cost between $1,700 to $2,000. A seat on a jet from Los Angeles to New York is usually around $3,500, one-way.
(Read More: Captain of your own yacht (this weekend, anyway))
"We're opening up private aviation to millions more passengers," Rothchin said. "For many of them, the app is the easy way to book."
Not every jet company is convinced of the potential for apps. Todd Rome of Blue Star said that while apps can build awareness and a broader market, the ultra-wealthy clients who form the core of the private-jet market still prefer face time or phone time when booking.
"Our business has always been done person-to-person," he said. "At the end of the day, it's always been high touch and I don't think that's ever going to change."
Bradley Stewart, CEO of XOJet, the private-aviation company, said frequent users of private jets still demand a voice and person at the other end of the transaction. He said it's unlikely that very wealthy fliers will ever move solely to apps for bookings and flight management.
"Most people who are dropping $20,000 or $30,000 on a transaction want the security of knowing that there's someone on the other end of the line," Stewart said. "If things go wrong or if something happens, they have a lifeline."
He added that his customers are not requesting apps and "they're telling me they're not shifting away from dealing with another voice."
Still, many private jet companies are racing to develop new apps. Gotham Jets, the New York-based aviation advisory and management company, has started working on an app that it hopes to launch early next year. The company said apps allow retail customers to get direct access to real-time information on the availability of planes and flights—data that used to be reserved mainly for brokers and charter companies.
"There is definitely a market there for apps," said Gotham Jets CEO Gianpaolo De Felice. "You're instantly bringing all that information to thousands of consumers. Imagine a group of friends who want to go to Miami. They click on the app and see a plane available at Teterboro tomorrow morning for a certain price. It becomes more attractive."
—By CNBC's Robert Frank. Follow him on Twitter @robtfrank.