Two and a half years after the chief of the low-fare airline Ryanair first dangled the idea of cheap flights between London and New York - with some tickets selling for as little as $10 - no viable low-cost airline has taken wing across the Atlantic.

But the financial problems facing long-established carriers may be changing the calculation. Jet leasing costs are falling as full-service airlines increasingly idle jets. And large numbers of pilots, flight attendants and ground staff members are looking for work.

Two European low-cost operators have recently announced plans to start intercontinental service next year, seizing what they see as a prime opportunity. Meanwhile, more passengers are scouring the Internet for the cheapest fares for business and leisure travel.

''From the point of view of the supply side, it is a good time'' because established airlines ''are having enough troubles of their own that they can't devote the resources to try and run these kinds of competitors out of business,'' said Peter Morris, chief economist with Ascend, an aviation industry consultant in London. ''On the demand side, clearly the market is weak.''

For more than a decade, both business travelers and backpackers have embraced the concept of no-frills transport over relatively short distances, like Paris to Pisa, Charlotte, North Carolina, to Chicago or Bangkok to Bali.