A technology entrepreneur on Monday unveils a new kind of on-demand airline that could alter the way people travel between midsize cities.

DayJet, of Delray Beach, Fla., will marry two advanced technologies: Very Light Jet (VLJ) aircraft, which can seat four passengers and operate at half the cost of today's small jets; and sophisticated computer databases that can determine the most efficient ways to route those aircraft to pick up customers.

The service will be halfway between a private jet charter and an airline, says DayJet CEO Ed Iacobucci, founder of software company Citrix Systems.

Customers would go to DayJet's Web site and enter cities on DayJet's route map that they want to fly between. Customers would put in dates and time parameters, such as "depart no earlier than" and "arrive no later than."

If a DayJet plane is available, the user would get a guaranteed confirmation. The system would try to fill all the seats on a given flight, though it would not be required. The flight would go even with only one passenger aboard, and the price would be the same no matter how many take the flight.

Expected cost: slightly more than full-fare coach tickets on those same routes, Iacobucci says. Service is expected to begin in mid-2006, with plans to expand to 30 markets by the end of 2007. DayJet will focus on mid-sized cities, such as Asheville, N.C., that it considers under-served by major airlines.

"It will pose a threat to the commuter airlines," says Henry Harteveldt, an analyst at Forrester Research. "A lot will depend on pricing and reliability."

Interesting idea if it "flies". -LB`