It’s a discussion that has raged since the first commercial air services. Who is the largest airline in the world and on what basis?

For some, the measurement is Available Seats Kilometres (ASKs); for others it’s the number of aircraft operated. Whilst some believe it’s the number of aircraft, others measure by the number of cities or countries served. Some airlines like to talk about their revenue (although not frequently profitability) and some base size on the number of flights operated in a year.

At OAG, we have provided some valuable data that will help that discussion as we have produced a ranking based on the number of scheduled seats, highlighting just how much the world is changing.

Rather like the English Premier League, there is a 'league within a league'. The 'Premier' league comprises of the 'US Big Four' of American, Delta Air Lines, United and Southwest. And then the second half of the league is led by Ryanair and the two largest Chinese airlines: Southern and Eastern respectively.

Movement up and down the league takes time and considerable investment; change is slow but not impossible. China Eastern could move ahead of China Southern at some stage; it is only separated by six million seats per annum. Or, perhaps easyJet could overhaul Turkish Airlines where a 2 million scheduled seat “gap” exists. Could Lion Air, with the largest outstanding aircraft order amongst the top twenty, rise from nineteenth to perhaps the top ten in the next decade? Who knows?

OAG’s Take Off metrics on the world’s major airlines will provide valuable insight to who is the largest of them all. But we don’t want to stop the discussion; after all what else would we talk about?!

To see the full Take-Off rankings, download our results below.

You can now find updated metrics in OAG Take-Off October 2017, showing you the essential statistics of the global Top 20 carriers from data taken between September 2016 - October 2017.