Ryanair, the controversial Irish budget airline, is in hot water again. 

The Irish Aviation Authority is investigating the airline after passengers complained they were being forced to pay an extra £10 (or about $16) to sit in seats by emergency exits.  

Passengers like these seats because they offer more leg room.  While the airline isn't the first to charge for the extra space, they're refusing to let passengers who haven't paid sit there, yet nearby passengers are still expected to man the exit door in case of emergency.  

"I wasn't allowed to sit in the emergency exit row so I sat in the window seat in the row in front. Before take-off, one of the cabin crew spoke to me, and another passenger who was in the aisle seat," a Ryanair passenger told the Daily Mail. "Basically, she was saying that, since we were the closest to the emergency exit, we'd have to make sure we'd read and understood the instructions for opening the doors in the middle of the plane in an emergency."

Ryanair head of communications Stephen McNamara told TNT magazine that this is a non-issue, since all Ryanair passengers are given the same safety information.

The Irish Aviation Authority has launched an investigation. The U.K. regulator, the Civil Aviation Authority, has described the issue as a ‘grey area', advising Ryanair to look at its policy.

The no-frills airline has, over the years, imposed surcharges on just about everything.  All passengers must now check-in online and print their own boarding pass, costing £6 per flight (about $10). Those passengers who don't have to pay a surcharge of £60 (or about $95 per passenger).  It also raised eyebrows for a plan to install coin-operated toilets on the planes, and for giving a passenger suffering a cardiac arrest a sandwich, and then charging him for it.