Southwest Airlines will begin charging customers a fee to check bags. It's a significant change for the budget carrier, which built years of advertising campaigns around its policy of letting passengers check up to two bags for free.

The carrier announced Tuesday that it will begin charging certain passengers to check their luggage on flights, a significant shift at the company long prized by consumers for its perks.

Southwest sent shockwaves through the aviation sector and wider business world March 11 when it announced that many customers would start being charged for checked bags. "Bags fly free" was a staple slogan for the Dallas-based airline,