The snag is that multi-carrier signals do not travel as far as single-carrier ones, so they require the construction of expensive repeater stations.

ECONOMIST: Power-line technology

Retailers must now charge shoppers at least five pence for each new single-use carrier bag.

BBC: Northern Ireland's new five-pence carrier bag tax

The Northern Ireland Executive will bring forward legislation later this year to introduce a 5p charge for single-use carrier bags in April 2013.

BBC: Plastic bags: Welsh government urges charges for rest of UK

Overall, the flying capacity of the carrier increased in high single-digits in the fourth quarter of 2012, compared to the year-ago period.

FORBES: Alaska's Earnings Will Get A Tailwind From Higher Capacity & Passenger Traffic