The Civil Aviation Authority claims the airline is not complying fully with European consumer law designed to support passengers following flight disruption.
Ryanair is not paying proper compensation for delays caused by technical faults and is attempting to impose a two-year claim limit from the date of the flight, according to the authority.
The regulator’s chief executive Andrew Haines said: “The law is clear that compensation must be paid if a flight is delayed for more than three hours by a routine technical fault.
“It is also clear that air passengers have up to six years to issue a compensation claim at court. This position was reaffirmed by the Court of Appeal last year.
“The Civil Aviation Authority is committed to protecting the rights of air passengers and we are determined to ensure all airlines comply with this regulation.”
The authority’s review of airline policies has already led to Jet2, Aer Lingus and Wizz Air changing their positions.
But Ryanair insisted that it “fully complies” with compensation rules, adding that they are “a fundamental part of our customer charter”.
The airline’s director of customer service Fiona Kearns said the airline would look to clarify its position in a meeting with the authority.
“Ryanair fully complies with EU 261 regulations which is a fundamental part of our customer charter. Ryanair has requested an early meeting with the CAA to clarify any misunderstandings that may have arisen in dealing with some historic cases.
In an open letter to Mr Haines, the airline stated its surprise at a press release from the regulator dated September 18 which “appears to have been issued within 24 hours” of a letter sent two days earlier inviting Ryanair to a meeting to discuss what it refers to as non-issues.
On Thursday. the European Court of Justice found in favour of a Dutch couple who were refused compensation by KLM because of a delay caused by a technical problem.
Richard Lloyd, executive director of UK Consumers’ Association, Which? said: “The regulator is right to take legal action against any airline that is failing to comply with the law. Airlines must be held to account and consumers should claim the compensation they are rightly owed if they have a lengthy delay and their carrier is at fault.”
Last month, Manchester County Court ruled against Ryanair in a test case taken by six delayed passengers who tried to claim compensation for delayed flights after five years and eight months, which Ryanair contested.
After a long-running legal battle, Judge Platts ruled that Ryanair’s rules fall foul of European Flight Delay law.
In a statement at the time, Ryanair said: “We note this ruling which reverses lower court orders that a two-year time limit for claims is reasonable.
“Since we believe a six-year time limit for submitting such claims is both unnecessary and unreasonable, we have instructed our lawyers to immediately appeal this ruling.”