Ryanair has clarified customer entitlements for passengers affected by cancellations.
It has issued a clarification e-mail to all affected customers - outlining their rights to refunds, re-routing on Ryanair or on other carriers and expenses.
Ryanair says it has e-mailed all customers who were affected by 2,100 flight cancellations in September and October - as well as the 18,000 schedule changes, announced on Wednesday, to explain their entitlements.
Sample e-mail from Ryanair
It has also explained to customers how and when they will be re-accommodated on other Ryanair flights or with other airlines.
Refund or re-routing
It says affected passengers will either be offered a refund option or re-routing option.
As part of the refund option, it says a full refund will be given of an unused flight sector and associated fees.
If the disrupted flight is outbound, customers will also be offered a full refund of the return sector.
In the re-routing scenario, Ryanair will offer to first move the customer to the next available flight on the same route.
If this option is not available the same or next day, then it will move the customer to the next available Ryanair flight from/to a suitable alternative airport.
While if this further option is not available the same or next day, then the carrier will offer the customer re-accommodation on any one of its agreed disruption partner airlines to their destination: Easyjet, Jet2, Vueling, Cityjet, Aer Lingus, Norwegian or Eurowings airlines.
It says if this option is not available the same or next day, then it will offer the customer re-accommodation on any comparable alternative transport (another airline flight, train, bus or car hire) with the cost of this ticket to be assessed on a case-by-case basis.
Under an EU directive, Ryanair says it will also reimburse any "reasonable out of pocket expenses" incurred by customers as a result of these flight cancellations.
It says this is subject to receiving an EU261 expense claim form from customers supported by original receipts.
Ryanair’s Kenny Jacobs said: "We apologise again sincerely for the disruption and inconvenience our rostering failure has caused some of our customers."
"In addition, every single affected customer has received a travel voucher for a €40 one way flight (€80 return) for travel in October to March."
Full details from Ryanair can be read here
The UK's Civil Aviation Authority (CAA) had given the firm a deadline to sort out compensation after massive cancellations.
While the Taosieach Leo Varadkar has said people's and passengers rights need to be protected.
The Commission for Aviation Regulation (CAR) says Ryanair has taken on additional staff to ensure that all refunds are provided to affected passengers within seven working days.
While all claims for expenses and compensation are to be dealt with within 28 working days.
Passengers are dissatisfied with the outcome of this process are asked to submit a complaint to the CAR.
The CAA had pledged to bring "enforcement action" against the airline for failing to give customers accurate information about their rights.
The airline has pledged to fully cooperate with the CAA investigation.
Here, the CAR says it is dealing with 300 customer complaints about Ryanair each week - and expects that number to rise.
It is reminding people whose flights were cancelled with less than two weeks notice; they are entitled to €250 compensation.
On Wednesday the airline announced that it was suspending 34 routes between November and March – with around 400,000 passengers set to be affected.
The airline had already canceled 2,000 flights over six weeks because of the original rostering "mess-up" which disrupted a total of 315,000 passengers.
On Thursday, the airline cancelled hundreds of flights in and out of Dublin Airport over the winter season.
Additional reporting: Jack Quann