Britain’s competition watchdog said on Thursday that it had opened an investigation into Irish carrier Ryanair over fees that parents must pay to sit with their children. The no-frills airline requires at least one parent to sit with children aged two to 11 during a flight, but that means they must pay for what is called a “mandatory family seat”. The Competition and Markets Authority (CMA) is investigating whether the fee, typically around ₤8 ($11) per flight, is “unfair” under consumer law.