Boeing (BA 2.81%) is finally seeing the all-important Chinese market reopen to its airplanes, and the company gave an indication that it could ramp up production of its 737 MAX jet faster than many investors had expected.

It all added up to a strong December for the aerospace giant, with the company's shares up 12.5% for the month, according to data provided by S&P Global Market Intelligence.

Boeing gets a boost in important areas

Boeing has taken investors on a rough ride in recent years. The stock was beaten down first by the 2019 grounding of the 737 MAX due to safety concerns and then by the pandemic, which put airlines on the defensive and led to a cutback in new plane orders.

China continued to ban 737 MAX planes long after the rest of the world allowed the plane to resume operations, and future Boeing orders in the country got caught up in a wider geopolitical dispute between the United States and China.

But investors got good news on all fronts in December. A 737 MAX was delivered to China Southern Airlines mid-month, and by Dec. 29, all Chinese carriers who operate the plane had it back in service. China is the world's largest aviation market, and it would be very difficult for Boeing to fully recover without selling planes there.

The stock was also aided by apparent good news in the month that was initially interpreted as bad news. Reuters reported that Boeing has indicated to suppliers its planned boost in 737 production would occur roughly two months slower than originally expected, with the company anticipating going from 38 aircraft per month to 42 in February 2024.

But Boeing's official guidance only calls for 38 planes per month at year's end, and it appears most of Wall Street had expected the ramp up to happen in the second half of 2024. So, the news that Boeing actually hopes to get there in the first quarter was met with cheers.

Is Boeing a buy going into 2024?

Even after a strong December, Boeing stock is still down more than 40% compared to where it was in 2019 prior to the troubles. The company also has more than twice the debt now than it did then, the result of a campaign to make sure its balance sheet had the wherewithal to survive any near-term, pandemic-related turbulence.

The priority right now is paying down that debt, and that can only be done via the cash flow that comes with deliveries. Opening up China and ramping up production of the 737, Boeing's most popular airplane, are key steps to getting the company back to sound footing, but it will take time.

The worst is over for Boeing, and both the company and the stock appear to be heading in the right direction. But investors need to be aware that the turnaround will take time. And given Boeing's recent track record, there can be no guarantees the flight from here will be without turbulence.

For those intrigued by the sector, there are better aerospace stocks to buy.