What makes a low-cost carrier a low-cost carrier? And how does it differ from a network airline? The two worlds, once chalk and cheese, have been orbiting ever closer over the years and the line between the two is more blurred than ever before.
This has been one of things we've been looking at as we've been throwing ourselves into the sector at Airline Business this month with our annual low-cost carrier financial and traffic survey and, for the first time this year, an interactive edition of magazine covering low-cost sector.
If you've missed it, you can check out The Essential Guide To Low-Cost Carriers - which features an interactive treatment of annual financial rankings, a groovy timeline where you quite literally open a window to find out more about the evolution of low-cost carriers, and a cryptic picture quiz to send you down low-cost carrier memory lane.
Of course you could argue a better reflection of the sector might have been The Essential Guide to No-Frills and Hybrid Carriers. Okay it doesn't quite have the same ring about it, but does reflect that one size no longer fits all when it comes to low-cost operators.
The sheer variety of their operations - including long-haul flights - means a Virgin Blue or Air Berlin for example is a very different animal from a Ryanair. And the move to lure more lucrative business travellers over to low-cost carriers has seen many move into network carrier territory, such as embracing distrubition through GDS systems for example. And the different models make comparing like-with-like more complicated. Ryanair, for example, based on revenues for its March 2010 financial year, is the fourth largest operator behind Southwest, Air Berlin and easyJet - which have higher yielding traffic. But by passenger count Ryanair is by some distance larger than both Air Berlin and easyJet, and behind only Southwest.
So how to define a low-cost carrier? For me, while you can frame it with some tangible low-cost carrier ingredients - namely predominantly operating short-haul, point-to-point routes with a single fleet in a single class with a simple fare structure often to secondary airports - few low-cost carriers still tick all these boxes. Instead I think it is more about a low-cost carrier ethos and which side of the line the airline grew up on. And keeping this ethos will be key for low-cost carriers to retain their identity and cost advantage, as their models grow ever more sophisticated and their network counterparts bring their own costs down.
For more on low-cost carriers, open our interactive edition of Airline Business here
For more on the challenges facing low-cost carrier growth, read our recent analysis feature here