When it comes to the world’s fastest-growing airlines, established carriers are somewhat overshadowed by their low-cost brothers. On lists of the top 10 from 2012 to the present, more than half are low-cost airlines rapidly expanding in both numbers of aircraft and destinations.

For a 2012 list of the 10 fastest-growing airlines, results were compiled by Innovate, a part of Flightglobal, which measures airline capacity by multiplying the number of available seats by the number of kilometers (available seat kilometers, or ASK) or miles (available seat miles, ASM) flown. Vueling Airlines ranked No. 1 with a passenger increase of 40 percent from 2011 to 2012. Other airlines on the list include Lion Air, 34.6 percent; IndiGo Airline, 34.6 percent; Spirit Airlines, 25.3 percent; Allegiant Air, 25.3 percent; All Nippon Airways, 24.3 percent; Turkish Airlines, 24 percent; Norwegian Air Shuttle, 22.5 percent; Emirates, 18.4 percent; and Virgin Australia, 18.3 percent.

Norwegian Air Shuttle © Jiri Senohrabek | Dreamstime.com

In April 2014, the International Business Times listed 10 airlines at the forefront where growth is concerned. Besides an increase in aircraft and destinations, these carriers are capitalizing on emerging markets and undercutting the competition with lower costs. IBT compiled its list by looking at company profits, passenger traffic, number of destinations and plans for the future. Except for the addition of Pegasus Airlines and the deletion of Allegiant, IBT’s list is the same as Innovate’s 2012 list.

So which are considered the world’s fastest-growing airlines, how did they get there and what are they doing to stay on top?

In 2004, Vueling, a low-cost Spanish carrier, flew two Airbus A320s on four routes. In 2014, Vueling boasted a fleet of 90 aircraft flying more than 285 routes. In 10 years it expanded into a major low-cost competitor in Europe, and it shows no signs of slowing down. The airline announced 31 new routes for the 2015 summer schedule for a total of 140 destinations across Europe, Africa and the Middle East. And the airline plans for as many as 120 new planes to join its fleet between 2015 and 2020.

A Lion Air plane at Surat Thani Airport, Thailand © Settawat Udom | Dreamstime.com

Lion Air is the largest low-cost carrier in Indonesia, the world’s fourth most populous country. Based in Jakarta, it is rapidly becoming one of Asia’s fastest-growing airlines. Lion Air truly impresses in terms of its recent aircraft acquisition alone. The carrier presented Boeing with its largest commercial order to date when it finalized a $22.5 billion deal for 201 Boeing 737 MAX planes and 29 extended-range Boeing 737-900s in 2012. Then, in 2013, it announced a record order with Airbus for 234 medium-range Airbus A320s. Indonesia’s strengthening economy and growing middle class help to fuel Lion Air’s growth.

Only nine years old, IndiGo already ranks as India’s largest domestic carrier and was the only airline in the country to report a profit for 2012–2013. As of April, its fleet comprised 96 aircraft. The airline’s strong adherence to a low-cost model, buying only one type of aircraft and keeping operational costs as low as possible help stimulate IndiGo’s expansion. CAPA Centre for Aviation and SITA, the air transport IT and communications specialist, forecast the number of air passengers in India will reach 425 million or more by 2020, and IndiGo is working toward putting the infrastructure in place to meet the demand.

Spirit Airlines bills itself as an ultra low-cost carrier and is infamous for bargain prices and expensive add-ons. It may be the most complained-about U.S. carrier, but it is also the fastest-growing, which indicates price frequently wins out over service. Spirit is currently gearing up for a major expansion with 113 aircraft on order to join its current fleet of 56. At this time, Spirit flies to 52 destinations in the United States and Central and South America, with numerous new non-stop services being added this year.

The U.S. budget airline Allegiant Air was the only airline that did not make it from the 2012 top-10 list to the 2014 version. Chances are its various costs and investments affected its cost performance in 2014. According to the Centre for Aviation, Allegiant Air’s profits decreased 6.1 percent last year.

Replacing Allegiant on the list in 2014, Pegasus Airlines, a low-cost Turkish carrier, carried 17.3 percent more passengers in 2014 than in 2013, and its revenue increased by 29 percent. Besides adding destinations within Turkey and beyond, Pegasus extended its network to the African continent in January. It now serves 89 destinations in 39 countries.

All Nippon Airways © Bo Li | Dreamstime.com

All Nippon Airways, hardly an upstart, has been in business for 60 years and currently holds more than 50 percent share in the Japanese market. With an eye on the Summer Olympic Games, to be hosted by Japan in 2020, ANA is betting on a dramatic increase in demand. To this end, it placed a record order for 30 planes from Airbus and 20 from Boeing in 2014. While this expansion ahead of demand is considered a risky move by some, ANA anticipates the annual number of foreign visitors to reach as many as 20 million by 2020.

Turkish Airlines tripled its global market share in the last 10 years. In 2014, its sales revenue increased by 13 percent while the available seat kilometers grew by 16.3 percent. The airline was awarded “Best Airline in Europe” in both the 2013 and 2014 Skytrax World Airline Awards. Not one to rest on its laurels, the airline announced it will add 117 new Airbus aircraft to its fleet by late 2015. Already boasting the world’s largest international network according to the International Business Times, serving 224 destinations in 105 countries, Turkish Airlines strives to out-compete its Middle Eastern rivals to make İstanbul a global aviation hub.

Norwegian Air Shuttle, a low-cost airline based in Oslo, zoomed from 40 aircraft serving 87 destinations on 170 routes in 2008 to 85 aircraft serving 126 destinations on 391 routes by 2013. Unfortunately, an 11-day strike by 700 Scandinavian pilots this March caused the airline to experience a first-ever drop in passenger numbers. Bookings have picked up, however, and despite the setback passenger revenue kilometers are up.

Emirates, owned by the incredibly wealthy country of Dubai, has grown by leaps and bounds ever since it started business in 1985 with two leased aircraft. The airline maintains its main goal is quality, not quantity, but its rise from those two aircraft to a fleet of more than 200 carrying a record 44.4 million passengers in 2013–2014 proves its reputation for explosive growth in the aviation industry is not unwarranted. Currently, three U.S. airlines are raising objections to Gulf carriers’ growth in the American market, but Emirates still plans to make the United States its third-largest source of revenue.

Virgin Australia started in 2000 as a low-cost carrier called Virgin Blue, with two aircraft flying a single route. The collapse of Ansett Australia in 2001 propelled Virgin Blue into the position of Australia’s second airline. It continued to grow and in 2011 dropped its bargain approach, rebranding as Virgin Australia. Currently, Virgin Australia operates 135 aircraft serving 63 destinations at home and abroad. In 2014, Virgin Australia surpassed Qantas in passenger revenue kilometers.

These airlines may be the fastest-growing statistically, but how do they rate with the flying public? Skytrax Air Travel Rating and Reviews from customers in 2015 are varied and, while there’s always someone who’s unhappy with something at sometime, some airlines have more contented customers than others.

Spirit is, by a long shot, the most unpopular of the 10 fastest-growing airlines in these reviews. The airline has been heavily criticized for its hidden charges and pricey add-ons, not to mention uncomfortable seats and poor service.

Vueling customers complain of limited legroom, poor customer service and random protocols inconsistently enforced. Lion Air customers also complain of cramped seating as well as frequent and lengthy delays, further aggravated by inaccurate information about flight changes and cancellations. Pegasus Airlines passengers grumble about delays, unprofessional ground personnel and small seats.

Norwegian’s unhappy customers cite long delays with no compensation, poor customer service and difficulty getting water on flights. Passengers say Turkish Airlines’ online check-in is difficult or impossible to use, meaning having to stand in long lines at the airport to check in.

Emirates may pride itself on service, but not all passengers agree. Even formerly loyal Emirates passengers say service levels have declined significantly in the past couple of years. And Virgin Australia has been criticized for having unfriendly staff, poor service and dirty cabins.

The two of the world’s fastest-growing airlines that fared the best according to Skytrax reviews are IndiGo and ANA. Out of 20 reviews, 90 percent were positive for ANA and 85 percent for IndiGo, as contrasted with only 35 percent positive reviews for Norwegian and an appalling 20 percent for Spirit.