Boeing's coming under increasing pressure to make a decision about its proposed 787-10, which would be a stretched-out version of the Dreamliner.

The base model of the Dreamliner ? the version that was set to take its first flight in late August or early September ? is the 225-seat 787-8. Boeing also plans for a short-range 787-3 and a 260-seat 787-9.

But a handful of airlines have also been calling for an even bigger plane, a 300-seat 787-10, or "Dash 10."

Boeing was reluctant to do it at first. It already builds a family of 300-seat jets, the 777-200 series, which Boeing has spent a lot of time and money upgrading in recent years.

Boeing is in talks with a couple of proposed buyers, and 787 program chief Mike Bair says it's a matter of "when, not if" Boeing will launch a Dash 10 program.

The debate now is over just how big it will be. According to Stephen Udvar-Hazy ? the CEO of International Lease Finance Corp., the world's largest jet-leasing firm ? there are "two camps."

"The quandary with the Dash 10 is that some airlines want more capacity and there are some airlines that want more range," Hazy says. Boeing is "trying to come up with a solution that satisfies both camps."

Put Qantas in the more-capacity column. CEO Geoff Dixon spoke out strongly in July, saying in Seattle that his Australian airline wants a 350-seat Dash 10, and if Boeing can't deliver it, he won't hesitate to buy an Airbus A350.

Hazy says the debate over size has delayed Dash 10 development by about a year, and Bair says the stretched plane probably won't be in service before 2013.