Ryanair passengers are being warned they still face a £55 airport charge as the airline introduces a new boarding pass rule.

The budget airline charges passengers a fee between £30 and £55 for checking in for flights at the airport, rather than online or via the Ryanair app, and this fee is charged per passenger. It means that a family of four faces being stung with a £220 on the spot charge at the airport, simply to check-in.

The airport check-in fee is free for Flexi Plus passengers, but only if flights have been booked through the Ryanair website or app. Ryanair passengers are being reminded to check-in online or via the app before going to the airport to avoid the charge of up to £55.

The reminder comes after the airline introduced a ban on printed boarding passes last week. As of November 12, Ryanair will no longer accept boarding passes that have been printed out at home and instead, passengers will be issued a digital pass when they check in.

In the event phones run out of battery after checking in, passengers will be allowed to get their boarding passes printed for free at the airport - but you'll only get it free if you've checked in online.

Explaining the new rules, Martin Lewis' Money Saving Expert (MSE) said: "From Wednesday 12 November, Ryanair will no longer accept home-printed boarding passes. You'll instead automatically receive a digital boarding pass when you check in online or on the app. You MUST still check in online or on the Ryanair app before you go to the airport. Fail to do this and, as is already the case, you'll be charged an airport check-in fee of between £30 to £55, depending on the flight.

"If you lose your phone or it runs out of battery after checking in, you can get a boarding pass printed at the airport for free. This previously cost £20. From 12 November, as long as you've checked in online, you won't be charged this extra fee.

"Where countries demand paper boarding passes, for example Morocco, you'll need to check in online, then present your digital boarding pass via the app or Ryanair website at the airport. Ryanair will then print a paper pass for you free of charge."

To avoid being stung by the £55 charge, passengers must check-in for flights before arriving at the airport, but there is a limited window in which to do this and, crucially, you have to remember to do it.

Ryanair says online check-in opens 60 days before the scheduled departure time if you've paid for an allocated seat, but if you haven't bought a seat and opted for the free random seat allocation, then online check-in opens 24 hours before departure.

The online check-in closes two hours before your flight is due to depart, so passengers need to complete it within this time frame to avoid being charged £55 at the airport.

Ryanair said: "You must check in online at www.ryanair.com and print or download your boarding pass, unless you have a Flexi Plus ticket, in which case you can check in at the airport for free.

"Unless you have a Plus or Flexi Plus ticket, if you do not check in online more than two hours before the scheduled departure time, you will be charged the airport check-in fee set out in our table of fees.

"The check-in desks close strictly 40 minutes before the scheduled departure time unless you are notified otherwise before flight departure. If you do not check-in by then you may be denied boarding without refund."