Anairline hub orhub airport is anairport used by one or moreairlines to concentrate passenger traffic and flight operations. Hubs serve as transfer (or stop-over) points to help get passengers to their final destination.[a][b] It is part of thehub-and-spoke system. An airline may operate flights from several non-hub (spoke) cities to the hub airport, and passengers traveling between spoke cities connect through the hub. This paradigm createseconomies of scale that allow an airline to serve (via an intermediate connection) city-pairs that could otherwise not be economically served on anon-stop basis. This system contrasts with thepoint-to-point model, in which there are no hubs and nonstop flights are instead offered between spoke cities. Hub airports also serve origin and destination (O&D) traffic.
The hub-and-spoke system allows an airline to serve fewer routes, so fewer aircraft are needed.[3] The system also increases passenger loads; a flight from a hub to a spoke carries not just passengers originating at the hub, but also passengers originating at multiple spoke cities.[4] However, the system is costly. Additional employees and facilities are needed to cater to connecting passengers. To serve spoke cities of varying populations and demand, an airline requires several aircraft types, and specific training and equipment are necessary for each type.[3] In addition, airlines may experience capacity constraints as they expand at their hub airports.[4][5]
For the passenger, the hub-and-spoke system offers one-stop air service to a wide array of destinations.[3][6] However, it requires having to regularly making connections en route to their final destination, which increases travel time.[6] Additionally, airlines can come to monopolise their hubs (fortress hubs), allowing them to freely increase fares as passengers have no alternative.[4] High domestic connectivity in the United States is achieved through airport location and hub dominance. The top 10 megahubs in the US are dominated byAmerican Airlines,Delta Air Lines, andUnited Airlines, three of the four largest United States–based airlines.[7]
Airlines may operate banks of flights at their hubs, in which several flights arrive and depart within short periods of time. The banks may be known as "peaks" of activity at the hubs and the non-banks as "valleys". Banking allows for short connection times for passengers.[8] However, an airline must assemble many resources to cater to the influx of flights during a bank, and having several aircraft on the ground at the same time can lead to congestion and delays.[9] In addition, banking could result in inefficient aircraft utilisation, with aircraft waiting at spoke cities for the next bank.[9][10]
Instead, some airlines have debanked their hubs, introducing a "rolling hub" in which flight arrivals and departures are spread throughout the day. This phenomenon is also known as "depeaking".[10] While costs may decrease, connection times are longer at a rolling hub.[9]American Airlines was the first to depeak its hubs,[9] trying to improve profitability following theSeptember 11 attacks.[8] It rebanked its hubs in 2015, however, feeling the gain in connecting passengers would outweigh the rise in costs.[8]
For example, the hub ofQatar Airways inDoha Airport has 471 daily movements to 140 destinations by March 2020 with an average of 262 seats per movement; in three main waves: 05:00–09:00 (132 movements), 16:00–21:00 (128) and 23:00–03:00 (132), allowing around 30 million connecting passengers in 2019.[11]
Before the US airline industry wasderegulated in 1978, most airlines operated under thepoint-to-point system (with a notable exception beingPan Am).[4] TheCivil Aeronautics Board dictated which routes an airline could fly. At the same time, however, some airlines began to experiment with the hub-and-spoke system.Delta Air Lines was the first to implement such a system, providing service to remote spoke cities from itsAtlanta hub.[6] After deregulation, many airlines quickly established hub-and-spoke route networks of their own.[3]
| Airport | 2024 pax. | American | Delta | United | Southwest |
|---|---|---|---|---|---|
| Atlanta | 52,510 | 984 | 38,660 | 853 | 3,839 |
| Dallas/Fort Worth | 42,390 | 28,451 | 1,420 | 984 | 0 |
| Chicago–O'Hare | 38,620 | 8,048 | 1,296 | 14,477 | 777 |
| Los Angeles | 37,864 | 5,238 | 6,341 | 5,481 | 3,312 |
| Denver | 37,840 | 1,262 | 1,726 | 15,585 | 12,524 |
| New York–JFK | 31,304 | 3,224 | 7,817 | 0 | 0 |
| Charlotte | 28,508 | 19,857 | 555 | 453 | 393 |
| Las Vegas | 28,024 | 2,181 | 2,498 | 2,034 | 10,552 |
| Orlando | 27,839 | 2,181 | 2,498 | 2,034 | 10,552 |
| Miami | 26,454 | 15,174 | 1,791 | 898 | 736 |
| Phoenix–Sky Harbor | 25,573 | 8,411 | 1,703 | 1,441 | 8,342 |
| Seattle/Tacoma[c] | 25,428 | 936 | 5,128 | 1,274 | 1,079 |
| San Francisco | 25,129 | 1,653 | 1,943 | 10,732 | 984 |
| Newark | 24,553 | 1,034 | 814 | 14,282 | 0 |
| Houston–Intercontinental | 23,377 | 961 | 963 | 13,093 | 298 |
| Boston | 21,217 | 2,456 | 4,300 | 1,765 | 932 |
| Minneapolis/St. Paul | 18,018 | 627 | 10,567 | 657 | 859 |
| Fort Lauderdale | 17,050 | 960 | 1,992 | 1,173 | 1,950 |
| New York–LaGuardia | 16,714 | 2,137 | 3,776 | 1,024 | 1,627 |
| Detroit | 16,083 | 712 | 9,050 | 246 | 516 |
| Philadelphia | 15,082 | 7,536 | 834 | 558 | 680 |
| Salt Lake City | 13,529 | 607 | 7,838 | 506 | 1,469 |
| Baltimore | 13,159 | 532 | 778 | 502 | 9,331 |
| Washington DC–Dulles | 13,065 | 113 | 376 | 6,623 | 164 |
| San Diego | 12,752 | 1,497 | 1,524 | 1,543 | 3,991 |
| Washington DC–Reagan | 12,733 | 3,463 | 1,200 | 732 | 1,855 |
| Tampa | 12,043 | 1,790 | 2,050 | 1,213 | 2,992 |
| Nashville | 12,035 | 1,102 | 1,155 | 762 | 6,326 |
| Austin | 10,664 | 1,926 | 1,444 | 1,179 | 4,418 |
| Chicago–Midway | 10,391 | 0 | 150 | 0 | 9,241 |
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In 1974, the governments ofBahrain,Oman,Qatar and theUnited Arab Emirates took control ofGulf Air from theBritish Overseas Airways Corporation (BOAC). Gulf Air became theflag carrier of the four Middle Eastern nations. It linked Oman, Qatar and the UAE to its Bahrain hub, from which it offered flights to destinations throughout Europe and Asia. In the UAE, Gulf Air focused onAbu Dhabi rather thanDubai, contrary to the aspirations of UAE Prime MinisterMohammed bin Rashid Al Maktoum to transform the latter into a world-class metropolis. Sheikh Mohammed proceeded to establish a new airline based in Dubai,Emirates, which launched operations in 1985.[14]
Elsewhere in the Middle East region, Qatar and Oman decided to create their own airlines as well.Qatar Airways andOman Air were both founded in 1993, with hubs atDoha andMuscat respectively. As the new airlines grew, their home nations relied less on Gulf Air to provide air service. Qatar withdrew its share in Gulf Air in 2002. In 2003, the UAE formed another national airline,Etihad Airways, which is based in Abu Dhabi. The country exited Gulf Air in 2006, and Oman followed in 2007.[14] Gulf Air therefore became fully owned by the government of Bahrain.
Emirates,Qatar Airways,Saudia andEtihad Airways have since established large hubs at their respective home airports. The hubs, which benefit from their proximity to large population centres,[14] have become popular stopover points on trips between Europe and Asia, for example.[15] Their rapid growth has impacted the development of traditional hubs, such asLondon-Heathrow,Paris-Charles de Gaulle, andNew York-JFK.[16]
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Acargo hub is an airport that primarily is operated by acargo airline that uses the hub-and-spoke system. In theUnited States, two of the largest cargo hub airports,FedEx'sMemphis Superhub andUPSLouisville Worldport, are close to themean center of the United States population. FedEx's airline,FedEx Express, established its Memphis hub in 1973, prior to the deregulation of the air cargo industry in the United States. The system has created an efficient delivery system for the airline.[17]UPS Airlines has followed a similar pattern in Louisville. In Europe,ASL Airlines,Cargolux andDHL Aviation follow a similar strategy and operate their primary hubs atLiège,Luxembourg andLeipzig respectively.[18]
Additionally,Ted Stevens International Airport inAnchorage, Alaska, is a frequent stop-over hub for many cargo airlines flying between Asia and North America. Most cargo airlines only stop in Anchorage for refueling and customs, but FedEx and UPS frequently use Anchorage to sort trans-pacific packages between regional hubs on each continent in addition to refueling and customs.[19]
Passenger airlines that operate in a similar manner to the FedEx and UPS hubs are often regarded asscissor hubs, as many flights to one destination all land and deplane passengers simultaneously and, after a passenger transit period, repeat a similar process for departure to the final destination of each plane.[20] In past,Air India operated a scissor hub at London'sHeathrow Airport, where passengers fromDelhi,Ahmedabad, andMumbai could continue onto a flight toNewark.[21] Until its grounding,Jet Airways operated a similar scissor hub atAmsterdam Airport Schiphol to transport passengers fromBangalore,Mumbai andDelhi toToronto-Pearson and vice versa. At the peak of operations at their former scissor hub atBrussels prior to the 2016 shift to Schiphol, flights operated from Mumbai, Delhi, andChennai and continued onward to Toronto,New York, andNewark after a near-simultaneous stopover in Brussels and vice versa.[22] An international scissor hub could be used forthird and fourth freedom flights or it could be used forfifth freedom flights, for which a precursor is abilateral treaty between two country pairs.
WestJet used to utilizeSt. John's as a scissor hub during its summer schedule for flights inbound fromOttawa,Toronto, andOrlando and outbound toDublin andLondon–Gatwick.Qantas similarly used to utilizeLos Angeles International Airport as a scissor hub for flights inbound from Melbourne, Brisbane or Sydney, where passengers could connect onwards if traveling toNew York–JFK.
In theairline industry, afocus city is a destination from which an airline operates limitedpoint-to-point routes.[24] A focus city primarily caters to the local market rather than to connecting passengers.[25][26]
Although the termfocus city is used to mainly refer to an airport from which an airline operates limited point-to-point routes, its usage has loosely expanded to refer to a small-scale hub as well.[27] For example, even thoughJetBlue's operations atNew York–JFK resemble that of a hub, the airline still refers to it as a focus city.[9]
A fortress hub refers to an airport where a single airline dominates the market share, making it challenging for competitors to establish a foothold.[28] This term is commonly used in the United States, where the airlines with the largest fortress hubs areDelta Air Lines atHartsfield–Jackson Atlanta International Airport,American Airlines atDallas Fort Worth International Airport, andUnited Airlines atDenver International Airport.
Most nationalflag carriers maintain a similarly dominant presence at their countries’ primary international airport, benefiting from historical advantages and market influence. Examples include:
A primary hub is the main hub for an airline. However, as an airline expands operations at its primary hub to the point that it experiences capacity limitations, it may elect to open secondary hubs. Examples of such hubs areAir Canada's hubs atMontréal–Trudeau andVancouver,British Airways' hub atLondon–Gatwick,Air India's hub atMumbai andLufthansa's hub atMunich. By operating multiple hubs, airlines can expand their geographic reach.[29] They can also better serve spoke–spoke markets, providing more itineraries with connections at different hubs.[1]
Cargo airlines likeFedEx Express andUPS Airlines also operate secondary hubs to an extent, but these are primarily used to serve regional high-demand destinations because shipping packages through its main hub would waste fuel; an example of this would be FedEx transiting a package throughOakland International Airport when shipping packages between destinations nearSeattle andPhoenix, Arizona instead of sending deliveries through theMemphis Superhub.[19]
A given hub's capacity may become exhausted or capacity shortages may occur during peak periods of the day, at which point airlines may be compelled to shift traffic to a reliever hub. A reliever hub has the potential to serve several functions for an airline: it can bypass the congested hub, it can absorb excess demand for flights that could otherwise not be scheduled at the congested hub, and it can schedule new O&D city pairs for connecting traffic.
One of the most recognized examples of this model isDelta Air Lines' andAmerican Airlines' uses ofLaGuardia Airport as a domestic hub inNew York City, due to capacity and slot restrictions at their hubs atJohn F. Kennedy International Airport. Many regional flights operate out of LaGuardia, while most international and long-haul domestic flights remain at JFK.
Lufthansa operates a similar model of business with its hubs atFrankfurt Airport andMunich Airport. Generally speaking, a marginal majority of the airline's long-haul flights are based out of Frankfurt, while a similarly sized but smaller minority are based out of Munich.
In past history, carriers have maintained niche, time-of-day operations at hubs. The most notable wasAmerica West's use ofLas Vegas as a primary night-flight hub to increase aircraft utilization rates far beyond those of competing carriers.
