The streamlined and lightweight family of MacBook Airs introduced by Apple late last year are a hit with consumers, who combined to demand shipments of more than 1 million of the new notebooks during the fourth quarter of last year.

Concord Securities analyst Ming-Chi Kuo tells AppleInsider that his most recent checks in Asia indicate Apple shipped a total of 1.1 million of its 11- and 13-inch MacBook Airs during the three-month period ending December, making the new breed of ultra-thin portables one of the company's most successful Mac product launches ever.

Those figures are about 63% higher, or 400,000 units more, than the 700,000 units that Kuo had initially estimated. The figures also support an earlier claim by AppleInsider that the new MacBook Airs quickly grew to comprise more than a third Mac maker's notebook business in the fourth quarter, selling at a 1 to 2 ratio to the company's flagship MacBook Pro offerings.

For example, Apple, which doesn't break down its Mac or device sales by product family for competitive reasons, said it shipped just over 2.9 million notebook systems during the fourth quarter of 2010. At 1.1 million units, the new MacBook Airs captured a 40% slice of the company's notebook business and accounted for just over a quarter of its Mac business as a whole.

Sales of MacBook Airs remain robust during the current quarter but are tracking down about 40% from the levels seen in their introductory quarter to just shy of 700,000 units according to Kuo. However, he estimates the Cupertino-based company may still set a new Mac sales record during the quarter with strong sales of its new MacBook Pros more than offsetting the decline in MacBook Air units.

In particular, he said, discussions with Apple's suppliers indicate the company's build plans call for the manufacture of upwards of 4.5 million Mac systems during the three-month period ending March. At those rates, Apple is likely to stand out as the only worldwide PC vendor to report material growth on a quarter-to-quarter basis, he added.