Now the passenger number gauge is level again, airlines can resume ‘up-gauging’

Industry trends | Apr 29, 2024 | By Satair | 6 min read

Increasing the number of seats on aircraft is a timely solution to the anticipated rise in passenger numbers heading towards 2025

The year 2019 was coming to an end: facemasks on aircraft were only ever seen on Halloween, and Corona was still just a Mexican beer brand. Nobody, anywhere, had any inkling of what was to come. 


Instead the aviation industry was basking in the results of a historic year for air travel. Passenger numbers had never been higher, and 2020 was expected to further eclipse the record 2019 totals.


Fast-forward four years and 2024 is the new 2020: the year in which global aviation passenger numbers will finally surpass the records set in 2019. October 2023 figures were higher than those set in the same month four years earlier, according to Naveo’s monthly Air Transport Traffic, Fleet & MRO Update report for November 2023 – the first time any monthly total had bettered pre-pandemic figures – and the projections for 2024 and the rest of the decade are buoyant, to say the least.


But there’s a spanner in the works, and it’s been obvious to the industry since 2019: there simply aren’t enough aircraft to satisfy the demand of the increasing passenger numbers.

The industry had an answer back then, and it’s the same answer today: Up-gauging. 

The wisdom of using wide-bodies on shorter flights

Up-gauging is when an airline increases the capacity of its flight: either by finding a way to add extra seats to an existing jet, or by replacing the existing jet with a bigger one.


Traditionally, airlines provide short and medium-haul flights on narrow body aircraft at a high frequency. The more popular the route, particularly with business travellers, the greater the frequency, as airlines will recoup the empty seat losses by selling the tickets at a premium.  

Wide body flights, meanwhile, tend to service long-haul markets at a much lower frequency. 

But are carriers beginning to see the wisdom of using wide body flights to service medium and even short-haul flights at a frequency in line with demand?


Not only does up-gauging make good financial and environmental sense, as bigger capacities decrease the Cost of Seat and individual carbon footprint, but they are also a good response to pilot shortages. 

Up-gauging the standard among major US carriers

Up-gauging has been an increasingly popular practice in the industry over the last 10-15 years – most notably in the US – chiefly to satisfy growing passenger demand. 


But up until the recovery from the financial crisis of 2008-09, the opposite was true: the industry had been steadily down-gauging.  Between 1992 and 2012, US airlines increased the number of their aircraft by around 30 percent to the extent that three flights in 2012 carried the same number of passengers as two flights in 1992. 


The tide turned in the late 2000s. Between 2013 and 2015, for example,  US airlines increased their aggregate domestic seating capacity by 12 percent, while operating 4.4 percent fewer flights. 


The advent of the A380 – the world’s largest commercial passenger jet, which made its maiden flight in 2007 – can be linked to this trend. In 2011, Lufthansa replaced two flights servicing the Frankfurt-NYC route with a single A380 service. 

Popular among European charter and budget airlines

Up-gauging of a similar fashion has also been ongoing in Europe since the beginning of the 2010s. 


TUI Airways – the world’s largest charter airline, which mostly flies holiday-makers from the British Isles to tourist destinations such as the Canaries and Caribbean – in 2013 became the first UK airline to take delivery of the 787 Dreamliner. The up-gauging, in line with its phasing out of the smaller 767, increased the average capacity of its flights by around 10-20 percent at a time when demand was increasing steeply.  

In similar fashion, easyJet is optimistic its  ‘fleet renewal and up-gauging plan’ will pay dividends:

We have an opportunity for further growth by investing in new, larger aircraft with greater seat numbers (known as up-gauging)

It has resulted in the average number of seats on the UK-based carrier’s flights rising from 173 to 180 since 2019.


It is achieving this by phasing out the smaller A319s – which have gone from transporting 41 percent of all passengers to just 31 percent in 2023 – and replacing them with the larger A320s and A321s. Late last year  it confirmed an order for 56 A320neo and 101 A321neo aircraft, which included the upsizing of 35 A320neo aircraft into larger A321neo models.

Up-gauging needs the airports onboard too

An airline can only up-gauge and acquire large aircraft if it has the assurance of the airport that it will be able to use gates big enough to handle the jumbos. Additionally, some runways simply aren’t reinforced or wide enough to accommodate the extra girth and weight of aircraft like the A380 – and likewise the aprons and taxiways.


Often extensive work is needed to adjust an airport’s infrastructure – both landside and airside facilities – to enable them to handle large aircraft or, as is often the case, increase the capacity to handle large aircraft.


Large aircraft will also impact peak passenger volumes, putting the entire configuration of the airport under pressure as well as the land transport access. And large aircraft increase the noise, which invariably means the airport needs to enter a consultation process with local stakeholders: most notably residents.

Reduces fuel costs and carbon footprint

Another factor often cited by airlines for the drive to up-gauge was the rise in fuel prices around the turn of the century. Bigger aircraft, when full, are considerably cheaper to fly than smaller ones, and US carrier Delta cited the lower cost per seat as the main reason for its 2012 decision to pursue a major up-gauging initiative. Not only did Delta replace a large proportion of its fleet serving domestic routes, but this meant its commuter partners had to follow suit. This saw hundreds of aircraft with seat capacities of 50 make way for bigger aircraft with 40 to 50 percent more seats.


The modern replacements have better fuel efficiency, which has been another reason why airlines have been overhauling their fleets over the last decade. The up-gauging has ultimately left Delta and its commuter partners with fewer aircraft but more seats – plus the added bonus of them being modern and more fuel-efficient. But this is just a temporary blip, claimed a  forecast, which predicted the US commercial fleet would increase from 7,039 aircraft in 2016 to 8,270 in 2037. 


study of US non-hub airports in 2017 noted that between 2006 and 2015 they lost 37.3 percent of their network legacy carrier flights, but only 22.6 percent of their seat capacity.

Reconfiguring interiors to add extra seats

Airlines can also up-gauge by reconfiguring their interiors to accommodate more seats.

On narrow bodies, there are a number of ways airlines can cut space to add more seats. They include:

  • Reducing legroom 
  • Using slimmer seats
  • Increasing overhead capacity, so passenger legroom is free of bulk
  • Making toilets more compact
  • Streamlining galley areas
  • Eliminating or relocating crew seats
  • Removing premium classes 

Wide bodies have more options, as they tend to have a greater mix of different classes. 

Retrofitting premium class areas can enable more seating, but getting rid of some of them altogether, and replacing them with more economy seating, has the greatest potential. The A380 capacity, for example, would rise from 525 to 853 with such a downgrade.  

Recent examples of an airline reconfiguring its interior to add more seats include:

  • Southwest Airlines increased the number of seats on its 737-700 from 137 to 143 – an addition achieved without “sacrificing comfort”
  • American Airlines added more seats to its 737s by reducing toilet sizes and the amount of passenger space (including in premium classes): from 150 to 160 and again to 172
  • easyJet reduced legroom to add an extra row to its A320s: an additional six seats


Few industries have changed as much as aviation this decade, but that doesn’t mean to say that everything on the table in 2019 has been flung aside. Up-gauging – the addition of seats to a flight, either by replacing the aircraft with a bigger version, or reconfiguring the interior – is back in fashion in what is expected to be the first in a series of all-time record years for passenger numbers. Given the limitations of airports, it’s the only way airlines can make sure they stay ahead of demand.