The World’s Most Heavily Used Aircraft Types - Answering The Big ASK

It appears that people are obsessed with measuring airlines. From the quality of service, the number of destinations served, on-time performance, passengers carried, load factors and just occasionally profitability, there are many interesting data points (many of which can be answered by OAG data). However, we rarely measure, or even note, one of the largest data points in the whole aviation industry - Available Seat Kilometres (ASKs). And even more rarely, ASKs by specific aircraft type; well until now!

Big Crunchy ASK Data

Within the airline industry ASKs are a key production measurement. However, airline analysts prefer to measure both RPKs (Revenue Passenger Kilometres) and CASK (Cost per Available Seat Kilometre). Understand all three “Ks” and you're halfway to evaluating how an airline is performing, and of course years of insights!

ASKs can be complex - two airlines flying the same route with the same aircraft type can generate two very different sets of ASKs as the table below shows:-


In both cases there is a difference in the ASK production, same distance, same aircraft type but different aircraft capacity. That one variable can result in a significant difference in ASK production. Of course, both British Airways and Lufthansa may argue that their RPKs are higher due to a better mix of traffic than their competitor, but only the accounts will be able to tell us that at some stage. 

Even based on one flight a day the ASK sum can be quite large, and this got us thinking about which aircraft type and airline have historically operated the most ASKs. By using OAG’s historical flight data (dating back to 1997) we can ask "What is the world’s most heavily used aircraft type? And which airline has operated the most ASKs?" 

Aircraft Leaders by ASKs Reflect Changing Global Markets

Some thirty-five years ago, the B747-400 was, at least in productivity terms, the leader in ASKs, with 31% more production than the combined total of all other B747 passenger aircraft. Indeed, half of the top ten were wide-bodied aircraft and interestingly at that time Airbus only had the A320 – 100/200 appearing on the list.


The fact that the B747-400 tops the list of ASKs by aircraft type for 1997 is perhaps no surprise. Airlines were, to a large extent, still operating in regulated markets and the concept of open skies was still in its infancy. Air travel was both a very expensive and luxurious experience; all of which lent itself to the B747-400. And, the largest operator of the aircraft, at least when measured by ASKs, was Singapore Airlines, with eight of the carriers being from the Asia Pacific Region - reflective perhaps of their geographic locations and distance to some (then) major markets, as much as the non-stop capabilities of the aircraft. For Singapore Airlines much of the B747-400 operation was based around markets to Europe and North America, including what looked like a valuable Seoul to Vancouver 5th Freedom flight.

Widebodies Ruled The Waves...Until 2008

Until 2008, the B747-400 ruled the waves as the largest aircraft type by ASKs. However, markets were becoming increasingly deregulated and air travel was becoming a necessity, usually as part of (at least) a yearly vacation. Despite this, there remained just four single-aisle aircraft in the list, but their popularity and ranking was growing.

By 2008, four of the largest A320 operators were based in the United States, reflecting in part the first round of airline consolidation that was taking part in the country, but also the growing demand for air travel across the continent. Major airlines such as Singapore Airlines and Cathay Pacific, whose entire operation was built around wide-bodied aircraft, fell out of the rankings, and we were beginning to see the emergence of the major Chinese carriers, such as China Eastern, in the list. a1

For JetBlue - the largest operator of the A320 in 2008 based on ASKs - JFK New York was the driver of their position, with a combination of some lengthy sectors such as Long Beach California, San Juan, and high daily frequencies in markets such as Ft Lauderdale driving big volumes of ASKs. 

A320s Hold Their Position

Since 2008 the A320 has held onto the crown as the most productive aircraft type flying, at least based on ASKs, and remains some distance ahead of its closest rival the B737-800 Passenger model in the rankings for 2022. A subtle change sees the balance between wide-bodied and single-aisle aircraft equally split at five aircraft types in the top ten, with a similar equal distribution between Airbus and Boeing - some nice coincidences there. 


Although the A320 continues to be the largest aircraft type from an ASK perspective, the changing market and shifting geographical balance is reflected in easyJet now leading the top ten airlines by ASK in 2022, and Indigo in a close second spot - increasingly edging closer to the leader. Whilst China Eastern, with the international reopening of their market, will undoubtedly be adding to their production in 2023.

Meanwhile, easyJet’s highest producer of ASKs in 2022 is their Luton – Tel Aviv service – who would have expected that? Additionally, seven of the top ten airport pairs are to or from a London Airport, highlighting the importance of this market to the airlines. And this summer easyJet will operate from four London airports, including of course their return to London Southend.


The evolution of ASKs by aircraft type since 1997 provides an interesting insight into how the market has changed, how increasingly deregulated markets and increasing demand for air travel have resulted in the balances of power changing. And, of course, technological advancements cannot be ignored, with longer flight ranges now the order of the day (see my recent post, Stretching Non-Stop Flights to the Limit). 

Dealing with these large numbers can be challenging, but working in thousands or millions of ASKs can make it easier to understand and analyze some of the data.  Big numbers allow for interesting insights; for instance, easyJet’s daily ASK production in 2022 was nearly the equivalent of a round-trip journey to Mars, whilst the A320 has (in ASK terms) completed more than 76,000 round trips to the planet.

Remember, if you do struggle with the numbers, you only need to ASK for the insights!


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