On an airline with a "premium economy" cabin, like Air New Zealand, coach customers bid to upgrade to premium economy and premium-economy passengers to business class.

WSJ: El Al, Virgin Atlantic Are Airlines That Auction Upgrades to Business Class

"We realized we had a premium customer sitting in economy class who would appreciate and purchase an on board culinary experience, " notes Russ Brown, U.S. Airways' director of product planning and development.

CNN: Economy class goes gourmet

"We have diversified our route network, focused on providing the best product in Upper Class, Premium Economy and Economy, hedged our fuel purchasing and built up a strong cash position, " he added.

BBC: Business travellers boost Virgin

Many companies with bans on business class travel have embraced premium economy as a way to offer employees a bit more space and comfort to rest or work without breaking the budget.

BBC: Flying in the fourth class