They said that this is leading to problem such as boarding and flight delays due to cabin bag removals, reports The Sun.
According to the Independent, since the airline relaxed its cabin baggage policy in 2014, allowing passengers to bring two bags, the "load factor" has increased from 82 to 97 per cent - meaning there are around 25 more cabin bags to be fitted in.
This luggage squeeze is delaying flights, and affecting the swift turn-arounds of flights.
According to the BBC, Ryanair said it had been a "victim" of its own "niceness" after allowing customers to take a second carry-on bag for free.
The policy, it said, had been abused with people taking on bags up to three times the permissible size - leading to delays.
So, from 15 January, only passengers who have paid £5 for priority boarding will be allowed two bags - one normal size (55cm x 40cm x 20cm) and one smaller bag (35cm x 20cm x 20cm), reports The Sun.
Passenger wheelie bags must be placed in the hold, free of charge at the boarding gate.
Ryanair will also be increasing its check-in bag allowance from 15kg to 20kg and actually reducing its check-in bag from £35 to £25 for a 20kg bag.
Ryanair's Kenny Jacobs says the new policy should reduce delays, adding that the move was not a money-making exercise. He said: "These bag policy changes will cost Ryanair over 50m euros (£46m) per annum in reduced checked bag fees.
"However, we believe offering bigger bags at reduced fees will encourage more customers to consider checking in a bag, which will reduce the high volume of customers we have with two carry-on bags at the boarding gates."
Ridiculous airline fees
Ridiculous airline fees
In the past, if you arrived at the airport early and there was a space on an earlier flight, you could put your name on the standby list and travel at no extra cost. Today, it's still possible to fly standby but it most often comes with a fee. American Airlines and United Airlines both charge a $75 move-up fee, while Delta Air Lines has a $50 Same-Day Travel Changes charge. The worst thing about this is that once you move to another flight, the airline can then re-sell your original seat and make a further profit.
Passengers who want a decent seat on their flight often have to pay extra - and that's not just with the low-cost airlines. Emirates charges a fee for advanced seat selection for economy passengers on a Special or Saver fare (AED 100/approx. £21 from the UK to the Middle East), British Airways charges between £7 and £20 for economy passengers and £20 to £55 for business class travellers, and picking your favourite spot on an Easyjet flight will cost you between £12 and £20 if you like the first row, from £7 to £14 for up front or overwing seats and between £1 and £6 for other seats. Meanwhile, Ryanair passengers are forced to pay up to £9 to select standard seats, up to £16 for priority seats and up to £22.50 for extra legroom seats.
In one of the most outrageous airline charges we've seen, United Airlines recently announced that it plans to charge passengers extra for using overhead lockers. The airline is introducing a 'basic economy' fare in 2017, which will allow travellers to carry a small bag that must be placed under their seat. Those who wish to store their belongings in the overhead lockers will need to purchase a standard economy fare. While United argues that it will not charge passengers more and simply offer a no-frills alternative, Reuters reports that basic economy fares "will be comparable to low fares it now charges for the economy cabin, but with more restrictions".
Similarly, passengers flying with Wizzair will need to pack light if they want to avoid extra charges as the airline only offers its customers a small cabin bag that is no larger than 42 x 32 x 25 cm - around the size of a small handbag or laptop bag. If you decide that you'll need extra clothing or a couple of pairs of shoes for your holiday and wish to pay for a larger cabin bag (no larger than 56 x 45 x 25 cm), you will be charged between £9 and £17.50 per bag, depending on the season. And that's if you add this extra via the call centre. At the airport, the fee rises to £36.
If you've booked a flight and at the last minute find out you can't make the trip, changing the name on your ticket to someone who can take your place will cost you with the airlines that actually allow for name changes. Ryanair charges a whopping £110 online or £160 at the airport, while making a name change to your Monarch flight will cost you a cool £100. With Easyjet, it's £45 if the amendment is made less than 60 days before you travel or £15 if it's more than 60 days. Travellers flying with WOW Air are charged £67.99 per fight leg and this is not available within 72 hours of flights to or from the USA.
Get cold on flights? It's worth bringing your own blanket if you want to avoid the charges from some airlines. Norwegian provides blankets to passengers for $5, Virgin America charges $10 for pillows and blankets and JetBlue offers unused pillows for $6 and unused blankets for $5.
Being penalised for paying your airline is about as unfair as it gets. While airlines are forced to pay a Merchant Service Charge to their bank for processing a card transaction, this is around 1 per cent but some airlines are still charging credit card users more. Monarch has a charge of 3 per cent or £5 per booking (whichever is greater), while Flybe's credit card fee is also 3 per cent of the total transaction value with a minimum charge of £5. Ryanair customers have to pay 2 per cent for using a credit card.
Can't handle a few hours being disconnected? In-flight WiFi is available with many airlines these days and while some are slowly introducing this for free, a number of carriers still charge for the service and updating your Facebook friends from the skies can be costly. Virgin Atlantic charges £14.99 for 150MB of data and Delta Air Lines charges $19 for 24 hours of continuous access on a domestic flight or $28 for a 24-hour global pass. Aer Lingus passengers can pay €7.95 for one hour or €14.95 for a full flight, and Finnair Economy passengers can access WiFi on board for €5 per hour or €15 for the entire flight.
Forgot to check in online? If you're flying with Ryanair it will cost you to check in at the airport unless you're a Business Plus passenger. The no-frills carrier has a £45 airport check-in fee, meaning you could end up forking out the amount you spent on your cheap flight if you don't remember to check in before reaching the airport. And if you think that's ridiculous, the fee was £70 before Ryanair reduced it in a bid to improve its image. Travellers flying with Wizzair are also charged a check-in fee of £26.50 at the airport, while Jet2.com passengers pay £17.50.
If you've successfully checked in online at home, you'd do well to remember to print your boarding pass if travelling with Ryanair as the airline charges a Boarding Card Reissue Fee of £15. Similarly, Jet2.com has a £17.50 administration fee for passengers who are unable to print or lose their boarding cards.