There are a few metrics by which to measure the traffic levels of an airport. Total departures, number of flights, or aircraft movements indicate how busy an airport’s apron, runways, and airspace are, more commonly used for operational purposes. From a commercial standpoint, these metrics can also be beneficial, but it’s more common to instead measure scheduled seats. OAG is the industry’s one-stop shop for submitting flight schedules, and it has now released traffic statistics for 2025, including the world’s busiest airports.

The world’s busiest airport is, once again, Atlanta Hartsfield-Jackson International Airport. It’s followed by the two busiest airports in Asia, Dubai International Airport and Tokyo Haneda Airport. Number four, meanwhile, is London Heathrow Airport, the busiest airport in Europe. London-Heathrow has been Europe’s busiest airport since 2023, and while it was ranked lower from 2020 to 2022, London-Heathrow had been ranked as Europe’s busiest airport for decades beforehand.

The London Metropolitan Area System Of Airports

London Heathrow Airport is the largest airport serving the London metropolitan area in the United Kingdom. While Heathrow is the world’s fourth-busiest airport in 2025, London consistently ranks as having the world’s busiest airport system. There are six major airports serving London, with London Gatwick Airport being the second-busiest airport in the area. While flag carrier British Airways centers most of its operations at Heathrow, it does have a significant presence at Gatwick and operates several long-distance routes.

London City Airport is the closest airfield to London’s major financial districts, and as such is heavily preferred by many business travelers. The catch is that London City Airport is small with a short runway, while its location means that arriving aircraft face strict noise-abatement procedures as well as a steep approach angle. Only a select number of aircraft are approved to operate out of London City Airport, with the largest being the Airbus A318-100, Airbus A220-100, and the Embraer E195-E2.

Stansted Airport, Luton Airport, and Southend Airport are all mainly served by budget airlines, located further away from London’s city center. Southend Airport is the least busy of the six, while Stansted and Luton are busier than London City Airport. London has by far the world’s busiest airport system, followed by New York with five (John F Kennedy International Airport, Newark Liberty International Airport, LaGuardia Airport, Westchester Airport, Long Island MacArthur Airport) and Tokyo (Haneda Airport, Narita International Airport).

London Heathrow Airport’s Current Traffic Levels

London Heathrow Airport has been ranked as Europe’s busiest airport for the third year in a row in terms of total scheduled seat capacity. In 2025, airlines scheduled 52.11 million seats to fly in and out of Heathrow Airport. In comparison, there were 51.55 million seats scheduled in 2024, whereas 2019 saw 50.17 million seats. Worldwide, London Heathrow Airport ranks fourth in scheduled seats, behind Tokyo Haneda Airport, Dubai International Airport, and Atlanta Hartsfield-Jackson International Airport.

Based on total international seat capacity, Heathrow Airport ranked second in the world, behind only Dubai. The airfield saw 48.97 million seats scheduled for international flights, slightly higher than 2024’s total of 48.36 million and 2019’s total of 47.19 million. This also places London-Heathrow ahead of Seoul Incheon International Airport, Singapore Changi Airport, and Amsterdam Schiphol Airport, all of which are renowned international connecting hubs.

Within Europe, the next nine busiest airports are Istanbul Airport, Paris Charles de Gaulle Airport, Amsterdam Schiphol Airport, Frankfurt Airport, Madrid-Barajas Airport, Barcelona El Prat Airport, Rome Fiumicino Leonardo da Vinci Airport, Istanbul Sabiha Gökçen Airport, and Munich Airport. The two Istanbul airports have grown rapidly in recent years, while Madrid, Barcelona, and Rome have also experienced steady growth. Meanwhile, Paris, Amsterdam, Frankfurt, and Munich have grown over the past year, but are still below 2019 levels.

The Two Airlines At London Heathrow Airport

London Heathrow Airport is home to two airlines: oneworld member British Airways and SkyTeam member Virgin Atlantic. British Airways, the older and larger of the two, was founded in 1974 as the result of the merger between BOAC (British Overseas Airways Corporation) and BEA (British European Airways), and it would later acquire Cambrian Airways, Northeast Airlines, as well as British Caledonian. In 2011, British Airways merged with Iberia to create International Airlines Group (IAG), which now also owns Aer Lingus, Vueling, and LEVEL.

Virgin Atlantic is the more recent entrant at Heathrow, having been founded in 1984. While British Airways is a large network carrier with a fleet of nearly 280 aircraft and a network that includes intra-European flights as well as intercontinental routes, Virgin Atlantic exclusively operates long-haul routes. The carrier only has a fleet of 43 aircraft, made up of the Airbus A330, A350, and Boeing 787. While the two airlines are fierce rivals on these long-distance routes, Virgin Atlantic is several times smaller and punches well above its weight.

A majority of British Airways flights operate out of Terminal 5, which is the largest freestanding building in the United Kingdom. British Airways shares Terminal 5 with Iberia, and also operates some flights out of Terminal 3. Virgin Atlantic, meanwhile, operates all of its flights out of Terminal 3, which is shared with British Airways, as well as several oneworld carriers and non-aligned airlines. Other SkyTeam airlines operate out of either Terminal 2 or Terminal 4.

Worldwide Air Service To London Heathrow Airport

London is essentially in a league of its own when it comes to global business and tourism demand, matched only by New York City. By scheduled seats, London Heathrow Airport to New York John F Kennedy International Airport is the world’s tenth busiest international route, and it’s also the busiest European international route, as well as the busiest North American international route. In addition, London sees significant service to Newark, but the same is not true for Gatwick, with Heathrow Airport being firmly established as the primary gateway to London.

British Airways is a oneworld member, meaning that other oneworld members (such as American Airlines, Qatar Airways, and JAL) receive access to huge feed when selling tickets to or from London. This greatly boosts the viability of starting or adding service to London. Of course, London itself has virtually limitless business demand to all corners of the world. In addition, the US, in particular, has seen a rise in « premium leisure » travel, and London is not only an iconic destination, but it feels more familiar to Americans than a nation with a foreign language. This has kept leisure and premium leisure demand strong from the US to London.

In total, nearly 90 airlines serve London Heathrow Airport. In addition, Heathrow is the world’s most connected airport, claiming this spot for the third year in a row. Heathrow has flights to 226 destinations across six continents, and at the airport’s peak in August 2025, passengers had access to over 59,000 connections within six hours. These figures are truly unmatched. London Heathrow Airport has also long held this spot, apart from its dip in passenger numbers during and shortly after the COVID-19 pandemic.

Future Expansion At London Heathrow Airport

London Heathrow Airport is the world’s second-busiest two-runway airport by scheduled seat count, behind only Dubai International Airport. By aircraft movements, which is the more relevant metric for considering runway operations, it is the world’s busiest two-runway airport. Because of these constraints and the exceptionally high flight volumes, the airport is slot-controlled.

Slots are allocated to airlines to operate a takeoff and landing at a specific time, and there are practically no new slots available at peak times, resulting in slots occasionally being traded between airlines for tens of millions of dollars. To address the lack of capacity, planners have announced the construction of a third runway. The new runway would be located to the northwest of the airfield and would come with new terminal buildings, along with a revision to the surrounding road system. The UK government has formally chosen a plan for the third runway, although the full green light is still years away.

This project is expected to be completed by the 2040s and is estimated to cost £49 billion. In addition, the project faces significant pushback from residents and environmentalists, who often argue over the true economic benefit of the third runway due to the environmental impact of additional flights. In the industry, however, a third runway would be a game-changer, as this would add significantly more capacity to London’s premier airport. Until then, however, Heathrow Airport will need to grow tepidly while slots trade for more than the price of some small aircraft.