Like a cloudburst erasing a rainbow, Boeing (NYSE:BA) has a knack for following good news with bad.

Early this week, the aerospace giant's stock rose on evidence that its sales drought was finally ending. Canada's WestJet was buying 14 Boeing 737-700 airplanes at a sticker price exceeding $800 million. According to its running tally, this brings Boeing's net new orders for the year to date to 47. (A vast improvement over the zero orders we were looking at just two months ago.)

But no sooner had Boeing scored this coup than out came the bad news. Over in Germany, patience is wearing thin at Air Berlin, where Aviation Week overheard the company's CEO grumbling about repeated delays in delivery of Boeing's 787 Dreamliner. According to AB's boss, this is "no fun anymore."

I suspect the quip elicited chuckles from fellow toe-tappers Delta (NYSE:DAL), Continental (NYSE:CAL), and AMR (NYSE:AMR). It has been a while since we last got a bit of good news on the 787 front. In contrast, bad news has been raining buckets -- the canceled test flight in June, the admission of a previously undisclosed Botox deficiency two weeks ago...

So if Air Berlin's boss is getting just a wee bit weary of performance that's "everything but satisfactory" at Boeing, you can understand his chagrin. From the top o' the supply chain where suppliers like Honeywell (NYSE:HON), United Tech (NYSE:UTX), and Spirit AeroSystems (NYSE:SPR) are raring to start cranking out Dreamliner parts, all the way down to the airlines waiting for assembled products, crunch time has come for Boeing.

Now here's the good news
As I argued last week, it's not so much the 787's technical glitches that have everyone upset. We know it's a novel airplane design. We expect glitches. But we don't expect Boeing to repeatedly set deadlines and then miss them. "Overpromise, underdeliver" is no way to run a business.

Which is why I was perversely pleased to see last week's rumor that the 787 test flight would come in November or December go uncommented upon by Boeing until its meticulous "Z18" planning document, which dictates all facets of the 787's production process, is fully finalized. Sure, it will be nice if "FlightBlogger" is right, and this nightmare is finally coming to an end. But from my perspective, it's much more important that Boeing gets it right this time.

Foolish final plea
No more missed deadlines, Boeing. You promised us a workable plan for bringing the 787 to market by the end of September. You've got six weeks left to make that happen. Use the time well. Get it right.

Is now the time to buy Boeing? Before it "gets it right," and investors get their reward? On Fool.com, we report, but at Motley Fool CAPS you decide. Click on over and tell us what you think.

Fool contributor Rich Smith owns shares of Boeing. Spirit AeroSystems Holdings is a Motley Fool Hidden Gems recommendation. The Motley Fool has a disclosure policy.