But shares of the Chicago-based aerospace and defense giant slipped 4.3 percent, as analysts viewed the profit gain as a given and were more concerned that costs of the 787 Dreamliner are creeping higher, while the company's cash generation, a key measure for investors, was low.

Last year, Boeing blew past its cash forecast, booking $9.7 billion in operating cash flow before pension contributions, compared with a forecast of more than $8.5 billion.

But this year Boeing has a lower forecast of more than $7 billion, and in the first nine months has booked only $4.6 billion. For comparison, it had already booked $8.3 billion at the nine-month stage in 2013.

"Where's the cash?" RBC Capital Markets Analyst Robert Stallard asked in the headline of a note to clients.

During a conference call with analysts and journalists, Boeing Chief Financial Officer Greg Smith said cash flow would be "very strong" in the fourth quarter. He didn't provide details, and Boeing's official forecast rose to "more than $7 billion" from "about $7 billion."

Smith also "laid out some pretty clear operating reasons for why the 787 is not going to see a massive or rapid shift in cash returns over the next year or so," Stallard told Reuters. Boeing is stocking up on parts for its 787-9 model, and would try to do the same with the -10 variant, as a way to lower the risk of production snafus, and that will consume cash, Smith said.

The deferred production costs of the high-tech plane now appear likely to reach $26 billion, up from the $25 billion Boeing had forecast, analysts suggested. Smith didn't contest the number but said he didn't see the cost reaching $27 billion.

Boeing shares fell to $121.68 in afternoon trading on the New York Stock Exchange.

In the quarter ended Sept. 30, Boeing earned $1.36 billion, or $1.86 per share, up from $1.16 billion, or $1.51 per share, a year earlier.

Core earnings, which exclude some pension and other costs, rose to $2.14 per share from $1.80, easily topping analyst forecasts of $1.97, according to Thomson Reuters I/B/E/S. Revenue rose 7 percent to $23.78 billion.

Commercial aircraft operating margins narrowed to 11.2 percent from 11.6 percent, reflecting the effect of deliveries of lower-margin 787 and 747 aircraft, Boeing said.

For 2014, the company upped its core earnings forecast to $8.10 to $8.30 per share, from $7.90 to $8.10.

Sales fell 2 percent to $7.9 billion at Boeing's defense, space and security business, reflecting continued pressure from government spending cuts. But Boeing boosted profit 27 percent and operating margins 2.4 percentage points by cutting costs.

(Reporting by Sweta Singh in Bangalore and Alwyn Scott in Seattle; Editing by Sriraj Kalluvila, Jonathan Oatis, Bernard Orr)

By Alwyn Scott