How many of Microsoft's ARM-powered Surface 2 fondleslabs has it sold so far during the presale period leading up to the tablet's October 22 launch? At least 11,000, as it turns out, because that's how many were snapped up by US passenger carrier Delta Air Lines.

"Delta is rolling out these new tablets to replace the traditional paper document flight bags you've probably seen pilots lug around in large briefcases, which weigh on average, a surprising 38 pounds each," Microsoft's Erwin Visser wrote in a blog post on Monday.

According to Mike Wysocki, Delta's director of flight operations technical and operational support – say that three times fast – the weight savings will spare more than pilots' arms. They'll also help lighten Delta's planes.

"In fact, the airline expects to eliminate the use of 7.5 million sheets of paper annually while reducing carbon emissions by 26 million pounds on 1.2 million fewer gallons of fuel," Wysocki wrote in a guest post to Redmond's corporate blog.

Doubtless Microsoft is pleased, too. Delta chose to go with the Surface 2, which is the ARM-powered version running Windows RT, rather than the more powerful Surface Pro 2.

The last time Redmond tried to hawk a Windows RT tablet, almost nobody bought it. Microsoft took an eye-watering $900m charge on unsold inventory of its original Surface in July, suggesting it had as many as six million units gathering dust in its warehouses. Other figures indicated that nearly all sales of Microsoft's slabs went to the Surface Pro (and even those sales figures weren't stellar).

This time around, Redmond is taking care to explain the differences between the Surface and the Surface Pro and the kinds of customers who might want each. In a nutshell, Surface Pro 2 is being marketed as a "laptop replacement", which Microsoft describes the ARM-powered Surface as "a tablet for business".

That's dramatically different marketing than what Microsoft tried with its first-generation Surface. That original model was pitched as a consumer device, and its TV ads featured young people dancing around, snapping and unsnapping their tablets from their colorful keyboard covers. Business, apparently, wasn't on the menu.

This time around, Microsoft has even cooked up a video to explain how the lightweight Surface 2 – which runs only Windows Store apps and isn't compatible with any traditional desktop Windows software, with the exception of Office – fits into Delta's business plans.

Fondleslabs or heavy briefcases? Delta and Microsoft think it's a no-brainer

This isn't the first time Delta has bet big on Microsoft products. In August, it announced that it had purchased Nokia Lumia 820 handsets running Windows Phone 8 for its global workforce of 19,000 flight attendants.

It's a safe bet that Delta didn't pay full price for either device, given such large purchases and Delta's willingness to help out with Redmond's marketing pitch, but just what kind of discounts Microsoft extended is something we may never know.

Delta says it spent "years" developing its "electronic flight bag" software for Surface 2 and that it will continue to work with Microsoft to "pursue technology and software innovations" for its workforce and its fleet. ®