Bob Knebel has never seen private aviation as a luxury. After all, as vice president of sales for Flexjet — the fractional business jet ownership program of Bombardier Aerospace — Knebel spends his days talking with executives for whom travel by corporate aircraft isn’t a perk or a status symbol; it’s simply the way they get to work. In the last year, however, with everyone from auto executives to members of Congress coming under fire for the use of private air travel, many of Knebel’s customers have asked him for something different.

“We had a customer about a year ago saying, ‘I need your service, I want your service, and I can afford your service. But I think it’s imprudent to purchase an asset in a rapidly declining market,’ ” Knebel said. “Our customers have discovered long ago that business jet travel is simply a necessity to get their jobs done. But they’re asking themselves about whether they need the same number of hours, or whether they have the right type of aircraft, or if it’s possible to minimize and not compromise. I think they’re asking all the right questions.”

The solution, Knebel said, is fractional jet ownership. Created by industry pioneer NetJets in 1986, fractional ownership allows customers to purchase a share of an aircraft for a set period of time — usually five years — splitting the use, fuel and maintenance costs of the plane with their fellow owners. Depending on the program, owners can upgrade or downgrade in order to take advantage of a variety of aircraft owned by the same company. They also enjoy all the benefits of owning their own airplane: privacy, security, the ability to schedule a flight on a few hours’ notice and access to 10 times the number of airports available to those flying on commercial airlines.

“We have an entire department dedicated to researching airports you’ve never even heard of,” said Marylynn McKeown, marketing manager for CitationAir, the private aviation division of Cessna Aircraft.

Fractional ownership makes sense for companies or individuals who spend 100 to 300 hours in the air annually, said Nel Stubbs, vice president and co-owner of Conklin & de Decker, an aviation cost consulting firm. Even firms that own their own jets may want to consider a fractional program as part of a range of flight options, Stubbs said.

“Just because you’ve decided to get into corporate aviation doesn’t mean you’re not going to be using the airlines sometimes,” Stubbs said. “A lot of times, a company will use corporate aviation for domestic travel and the airlines for international travel. They may also own their own aircraft but decide to go with a fractional share or a card program as supplemental lift.”

Participants in fractional programs pay up-front costs — including aircraft acquisition, pilot and crew management, and hourly occupancy fees — that can be significantly higher, in the long run, than the cost of owning and operating one’s own aircraft. Fractional owners also miss out on the opportunity to choose their own pilots and maintain their airplanes, although many owners don’t mind turning that responsibility over to a management company.

“With jet management services, we hire the pilots, find somebody to maintain the airplane and to fix it, so you don’t have to worry about that,” McKeown said. “It’s really a piece of cake.”

And while costs for fractional programs remain high, the recession has left some more willing to negotiate with their customers — and to provide new business models that better suit their needs.

“With the economy turning pocketbooks tighter these days, folks are much more focused on the hourly cost,” said Matthew Doyle, senior executive vice president of sales and marketing for Avantair, the fractional provider for Piaggio Avanti Aircraft. “And they’re extremely demanding. They don’t want to sacrifice comfort, safety or the newness of the aircraft.”

Yet some customers have shown they’re willing to sacrifice a little of what makes private aviation special in order to realize big savings. Under normal circumstances, for example, Citation Air customers have access to the company’s Cessna aircraft 24 hours a day, 365 days a year. But participants in the company’s JetShares program agree to eliminate up to 30 “premium days” such as Christmas and Labor Day from that schedule, dropping the cost significantly. Similarly, just by planning out their return trip in advance, those taking part in Flexjet’s Round Trip Pricing program can cut their hourly rate for those flights by 15 percent.

Flexjet’s Knebel said his company learned to be innovative during the last significant economic downturn — the dotcom crash of the late 1990s, a time he calls a learning period for both aircraft companies and customers.

“During that period of irrational exuberance, a lot of people jumped into the fractional segment without really understanding what the economics were. It was just ‘I have my share of an airplane, don’t you?’ ” said Knebel, who doubled his sales team in September despite the recession. “As they came to the end of those first contracts, we heard many of our customers saying they hadn’t gotten all that they could out of it. And we listened.”

Hearing that customers were upset by using more flight hours than their contract allowed — or leaving unused hours on their contract at the end of the year — Flexjet created its own version of “rollover” hours: “Versatility Plus,” a pool into which customers could deposit saved hours and withdraw from them at a later date. More recently, the company created its “Walk Away Lease” program, which allows customers the option to leave their contracts with just a 90-day notice, in hopes that it would encourage potential clients who might be skittish about committing to a five-year share.

While both programs have proven popular, Knebel and other fractional program representatives acknowledge their biggest sellers over the past year have been fractional card programs. Like debit cards, fractional cards allow members to charge flying hours against a deposit. Although card programs feature the highest per-hour costs in private aviation, those costs are still lower in the short term than any form of airplane ownership — a fact that has made them especially popular in the last year. At Avantair, for example, Doyle said the focus “has shifted slightly from fractional and more onto card-type programs. We’ve seen record sales in cards.”

The interest has prompted Avantair to create the “Access” program, a hybrid fractional/card promotion in which owners purchase 25-hour blocks of time over a three-year period at reduced rates. Flexjet has also expanded its card offerings in the last year, allowing customers to divide their hours between two different types of aircraft and the cost of those cards into two payments. CitationAir, which now includes both Cessna’s former Jet Card and Citation Shares programs, has recently introduced an offer that combines aspects of both: a 12-month membership at a one-time fee.

“Big corporations used to have plenty of aircraft, but with the changing economy, there’s been a change in perceptions,” McKeown said. “We recognize there’s still a need for these executives to go to remote places, so our solution was to offer a very simple contract that cuts the capital costs significantly and includes no long-term commitment.”

Although customers are more cost-conscious than ever, perks and partnerships are still available. Those who purchase a new Flexjet 25 card receive access to three top events and the closing ceremony at the 2010 Winter Olympics, as well as a behind-the-scenes meeting with an award-winning athlete. NetJets members have year-round access to medical services from the Mayo Clinic and ’round-the-clock care for their pets from the University of Pennsylvania Veterinary Hospital.

In the immediate future, however, the relationship between most customers and the fractional ownership companies with which they work is likely to be all business.

“Two or three years ago, it wasn’t uncommon for one or two folks to use a Gulfstream IV for a one- to two-hour flight, even though that kind of aircraft is not suited for that kind of mission,” said Avantair’s Doyle. “Now companies recognize that aircraft isn’t a perk: It’s a business tool, necessary to get out and travel efficiently. Programs like ours allow people to be at their destination in a significantly shorter amount of time. They can visit two or three cities in a day and then get back home; doing that on the airlines would take them a week to accomplish.”