Because of the charge the seats are increasingly left unoccupied because travellers won't pay for what amounts to a few extra inches of legroom. However, Ryanair, which incidentally is not by any means the only airline to make such a charge, says it still expects passengers in surrounding rows to follow directions on how to open these doors in an emergency.

The Irish Aviation Authority is investigating concerns that the travellers who are expected to man these doors in an emergency are not allowed to sit in these seats during the flight. The British Airline Pilots' Association (BALPA) also expressed concerns about the policy's safety implications. Since Ryanair introduced the rule, passengers who have not paid £10 extra are told they can sit anywhere but the first four rows and the emergency exit rows in the middle of the plane. This has resulted in many flights with the emergency exit rows empty.

Stephen McNamara, Head of Communications for Ryanair, said: "We do not believe this to be an issue as all Ryanair passengers are provided with the same safety and evacuation information. We will continue to discuss the matter with the IAA.'