Boeing's 787 Dreamliner has cost the company billions of dollars more than expected, pushing back the day when the program will start to make money.

But just what it means to be profitable is a complicated question, FlightBlogger noted Thursday.

Boeing considers the program profitable now, because it has spread its costs over anticipated sales well into the future. While the company previously assessed profitability of new programs by spreading costs over 400 sales, it may go as high as 1,000 for the 787, justifying this based on the airplane's big order total, FlightBlogger reported. Expect executives to divulge this figure next Wednesday, during the third-quarter earnings call.

Executives expect individual 787s to sell for more than they cost to build some time late in the decade. That's when Boeing will start chipping away at its tremendous investment in the aircraft.