How to spot them

1. Independent no frills: These one-class carriers offer a basic, flight-only service either through secondary gateways or on head-to-head routes with the majors and regional operators. Examples are Southwest, easyJet, Ryanair, Go Fly, Virgin Blue and AirAsia.

2. No frills subsidiaries of the established airlines: The low-cost airline-within-an-airline model was introduced mostly as a competitive response to other low-cost airlines, but also provides a vehicle for major carriers to drive down their own costs. Examples include KLM’s buzz, bmibaby (British Midland), JAL Express and Delta Air Lines’ Delta Express.

3. Hybrid operators: These are independent or subsidiaries providing a some-frills service (including access to premium facilities and frequent flyer programmes) within a low-cost operating structure. Examples are Australian Airlines, SilkAir, AirOne in Italy, AirTran, Frontier Airlines and JetBlue in the US.