How low-cost airlines work: costs, single-type fleets and ancillary revenue

A flight across Europe for less money than the taxi ride to the airport: that sounds like a business that cannot work. Yet low-cost airlines are among the most profitable airlines of all. The secret is not a single trick but that every decision in the company pays into the cost per seat – from the aircraft type through the cabin to the question of whether the aircraft sits on the ground for 25 or 60 minutes. This article shows you how the building blocks interlock and why, as a spotter, on some days you feel like you only see 737s and A320s.

Low-cost airlines in one sentence

A low-cost airline sells as many seats as possible with as little effort per seat as possible and earns extra on everything that goes beyond plain transport. The industry’s central metric is therefore the cost per available seat kilometer: what does it cost to move a seat one kilometer – whether it is occupied or not? Anyone who keeps this value permanently below that of the competition can offer lower prices and still make a profit.

Network airlines like Lufthansa or Air France earn their money differently: with connecting traffic through hubs, with several cabin classes, long-haul and business travelers who pay for flexibility. Low-cost airlines deliberately forgo much of that. The article Hub-and-spoke and point-to-point explains the difference between the two network logics in detail.

Where the model comes from

The idea comes from the US. Pacific Southwest Airlines flew within California from 1949 and is often called the world’s first low-cost airline. Because it only flew within a single state, it was not subject to the strict price regulation of the time for flights between states. Southwest Airlines adopted exactly this principle: Herb Kelleher and Rollin King founded the company in 1967, and in June 1971 scheduled service within Texas began – with Boeing 737s, short routes and simple processes. After the deregulation of US air transport in 1978, Southwest grew nationwide and still flies only the 737 today.

In Europe, Laker Airways first made headlines in the late 1970s with cheap transatlantic flights and failed. The breakthrough came from the gradual opening of the European market: with the third liberalization package, from 1997 any airline from the EU was allowed to offer domestic flights in other EU states as well. Ryanair had already reinvented itself by then. After losses in the late 1980s, the Irish airline switched from 1990 to a low-cost model modeled on Southwest, including an all-Boeing 737 fleet. easyJet started in 1995 out of London Luton, and Wizz Air followed in 2004 with a focus on Central and Eastern Europe.

Building block 1: the single-type fleet

The most visible feature for spotters is the fleet. Almost all big low-cost airlines rely on a single aircraft family:

Airline	Aircraft family	Main types	Seats in the main type
Ryanair	Boeing 737	737-800, 737-8200	189 and 197 respectively
easyJet	Airbus A320 family	A319, A320, A320neo, A321neo	depending on variant
Wizz Air	Airbus A320 family	mainly A321neo	239
Southwest	Boeing 737	737-700, 737-800, 737 MAX 8	depending on variant
Norwegian	Boeing 737	737-800, 737 MAX 8	depending on variant

The reason is simply money. Every additional aircraft family means its own type ratings for the cockpit, its own training for technical and cabin staff, an additional spare parts stock, its own tools and simulator time. With just one family, every crew can fly every aircraft. If an aircraft drops out at a base, any other takes over its rotation without seats, crew or handling having to be rescheduled.

Add to that purchasing power: anyone who orders hundreds of aircraft of one type at once negotiates completely different terms with Boeing or Airbus than an airline that needs ten aircraft. In 2023, Ryanair placed a firm order with Boeing for 150 737 MAX 10s and secured options on 150 more. For the Boeing 737-8200, a particularly densely seated version of the 737 MAX 8, the airline was the launch customer. How airlines plan such decisions over decades is explained in the article How airlines plan their fleet; why part of the aircraft is nevertheless rented rather than bought is covered under Aircraft leasing.

Building block 2: dense cabin, one class

An aircraft costs roughly the same per flight whether 150 or 200 people sit on board. Every additional seat spreads the fixed costs over more heads. Low-cost airlines therefore seat their aircraft in a single class and with as many rows as the certification and the number of emergency exits allow. The 737-8200 has 197 seats at Ryanair, the A321neo 239 at Wizz Air – at many network airlines, significantly fewer people sit in the same fuselage.

Everything that costs weight and effort is left out: inflight entertainment, elaborate galleys, in some cases even reclining seatbacks. Less weight saves fuel, less equipment saves maintenance, and a simple cabin can be cleaned faster.

Building block 3: time on the ground is expensive

An aircraft only earns money when it flies. The lease payment or depreciation keeps running even when the aircraft is at the gate. Low-cost airlines therefore try to keep their aircraft in the air as many hours a day as possible. The most important lever for this is the turnaround time, the span between arrival and the next departure. In its realignment after 1990, Ryanair set a turnaround time of around half an hour as its target.

This is made possible by a chain of simplifications:

• No connecting traffic: Without connecting flights, no baggage has to be checked through and no delayed feeder flight has to be awaited. If a flight is delayed, it affects only that rotation.
• Little checked baggage: Because suitcases cost extra, many travel with carry-on only. That shortens loading and unloading.
• Stairs instead of a jet bridge: Boarding across the apron, often at the front and rear simultaneously, is fast and saves fees. Many Ryanair 737s have onboard airstairs for this.
• No catering swap: What is on board is what gets sold; an exchange at every landing is omitted.
• Cleaning by the crew: On short turnarounds, the cabin crew often tidies up themselves.

What all happens in parallel between arrival and departure is shown in the article Turnaround: handling an aircraft. For spotters, the short turnaround is an advantage: a low-cost aircraft you see landing often takes off again after just half an hour.

Building block 4: airports and bases

Airport charges are a large cost block for an airline with low ticket prices, because they are incurred per passenger and per landing. Low-cost airlines therefore negotiate hard or move to smaller, so-called secondary airports. These are often less congested, have short taxi routes and offer discounts for new routes. How such charges are made up is covered under Airport charges explained.

Well-known examples are Frankfurt-Hahn Airport in the Hunsrück, Brussels-Charleroi Airport or Weeze Airport on the Lower Rhine. Alongside them are large bases at airports that are already heavily shaped by low-cost traffic, such as London Stansted and Milan Bergamo for Ryanair or London Luton for easyJet and Wizz Air.

Instead of a hub, low-cost airlines operate many bases where aircraft and crews are stationed overnight. In the morning, the aircraft depart from there on several round trips and return in the evening. This structure is flexible: a base can be opened, scaled down or closed comparatively quickly. For regional airports that is opportunity and risk at once – when an airline pulls aircraft out, a large part of the traffic disappears. Wizz Air, for example, closed its only German base in Dortmund in October 2021.

Building block 5: sales and staff

Low-cost airlines sell their tickets almost exclusively through their own website and app. That saves commissions to travel agencies and booking systems. Check-in is online, the boarding pass is on the smartphone, and counters at the airport exist only for baggage and special cases. Prices are dynamic: early bookings are cheap, and as load rises, the price rises. That way the airline fills its aircraft very evenly – in recent fiscal years, Ryanair has mostly achieved a load factor of over 90 percent.

With staff, low-cost airlines rely on high productivity: many flight hours per crew, few hotel nights thanks to the base model, lean administration. This area is at the same time the most controversial part of the model, because working conditions, contract models and employee representation have repeatedly been the subject of strikes and court cases.

Building block 6: ancillary revenue

The low base fare is only the entry ticket. Extra money is made on everything passengers book individually on top – in industry jargon, ancillary revenue. Typical items are:

• Checked baggage and larger carry-on baggage
• Seat reservation, seats with more legroom
• Priority boarding and faster security screening
• Food, drinks and duty-free on board
• Commissions for hotels, rental cars, transfers and insurance
• Fees for rebooking or check-in at the counter

At Ryanair, this area makes up just under a third of revenue according to common reference works. That fundamentally shifts the calculation: the airline can offer a flight below cost if it expects enough passengers to buy extras. Network airlines have meanwhile adopted this principle, for example with basic economy fares without baggage. And even Southwest, long known for two free checked bags, abolished that rule in 2025 and introduced assigned seating in 2026.

The limits of the model

As strong as the model is on short and medium-haul routes, it is hard to transfer. On long-haul, turnaround time hardly matters, because an aircraft is in the air for many hours anyway. Widebody jets are expensive, passengers want to eat and bring baggage on a ten-hour flight, and without connecting traffic demand is often lacking. The list of withdrawals is long: Oasis Hong Kong ceased operations in 2008, AirAsia X pulled out of Europe in 2012, and Norwegian finally gave up long-haul with the Boeing 787 in January 2021.

Narrowbody jets with long range such as the Airbus A321XLR, which Wizz Air has used since 2025, offer a new approach. They allow longer routes without leaving the single-type fleet.

Even on short-haul, the model is no sure thing. Rising costs for fuel and engine maintenance hit airlines with very low prices especially hard. The US ultra-low-cost airline Spirit Airlines ceased flight operations in May 2026 after two bankruptcy proceedings. And Wizz Air has had many A321neos on the ground since 2023 because their geared turbofan engines have to go to the shop early – a single-type fleet also makes you vulnerable when one problem affects all aircraft at the same time.

What this means for you as a spotter

The low-cost model shapes what you see at the fence. At many European airports, low-cost airlines account for a large share of movements – and thus a flood of similar aircraft. If you look more closely, you still find plenty to work with:

• Hunt variants: Boeing 737-800 and 737-8200, A320ceo and A321neo – within a fleet, several generations often run side by side, and the older ones gradually disappear.
• Subsidiaries and registrations: Behind one brand there are often several operating companies. At Ryanair Holdings, Malta Air, Buzz, Lauda Europe and Ryanair UK fly with their own ICAO codes and registration prefixes, and at Wizz Air there are HA-, 9H- and G- registrations.
• Wet lease in summer: In peak season, airlines rent aircraft with crew from other companies. That is how foreign types and liveries show up on low-cost routes – more on this under Wet lease explained.
• Capture fleets completely: With hundreds of aircraft of one type, large low-cost fleets are ideal for collectors who tick off registrations.

If you are planning a trip to a typical low-cost airport, the spotting guide for Frankfurt-Hahn is a good start. And if you want to know where the difference from the classic leisure airline lies, the article Charter flight and scheduled flight helps.

Conclusion

Low-cost airlines work because many small savings add up to a large cost advantage: one aircraft family, a dense single-class cabin, short ground times, cheap airports, direct sales and a base fare where extras supplement the actual business. Taken out of this interplay, every single building block loses effect – which is why the model has such a hard time on long-haul. For you as a spotter, it means many identical aircraft, but also plenty of details to discover.