Ryanair Holdings Plc and EasyJet Plc tightened their hold on the European discount sector last year, adding millions more passengers as low-cost rivals Norwegian Air Shuttle ASA and Air Berlin Plc struggled to grow.

Ryanair lifted customer numbers 6 percent to 86.4 million, consolidating the Dublin-based company’s position as market leader, while Luton, England-based EasyJet posted a 6.5 percent gain after carrying 65.3 million people. Both added passengers faster than they did capacity, so that occupancy levels rose.

In a push to gain market share, the leading discount players are boosting frequencies on key routes while targeting corporate travelers with add-ons such as allocated seats and flexible fares. While that’s squeezing network carriers led by Air France-KLM Group and Deutsche Lufthansa AG, which are being forced to restructure their short-haul businesses, it’s also widening the gap to other low-cost specialists.

Norwegian Air today said full-year passenger numbers were little changed at almost 24 million, while the tally at Air Berlin edged up 0.6 percent to 30 million. Both carriers offer short-haul flights that go head-to-head with Ryanair and EasyJet, as well as long-haul services using wide-body jets that the top two operators have so far eschewed.

EasyJet’s full-year load factor, or the proportion of seats filled, advanced 1.5 percentage points to 90.8 percent, it said today, while the figure at Ryanair rose 3 points to 86 percent, according to a statement on Jan. 5. Norwegian Air’s annual occupancy level edged up 0.2 points to 80.9 percent, while at Air Berlin the figure slid 1.4 points to 83.5 percent.

Fleet Gamble

Fornebu-based Norwegian needs to build traffic as it embarks on one of the industry’s most ambitious growth plans, swelling its European fleet with 222 mainly re-engined Boeing Co. 737s and Airbus Group NV A320s arriving from 2016 while rolling out long-haul flights using Boeing’s latest 787 model.

Air Berlin, caught between competition with low-cost operators and German No. 1 Lufthansa, is meanwhile retrenching, with the fleet to be cut to about 130 planes from 170 in 2011. The total had been reduced to 145 as of Sept. 30.

Ryanair aims to carry 90 million people in its current fiscal year ending March 31, 120 million annually by 2019 and 150 million within 10 years, having agreed in September to buy as many as 200 high-density Boeing 737s that could take the fleet to about 500 narrow-bodies.

Winter Challenge

The Irish company ramped up the challenge to rivals last month after dropping a strategy of grounding large numbers of planes for the winter, so that it’s December footfall surged 20 percent to just over 6 million people.

EasyJet, which has traditionally offered a more comprehensive winter timetable, lifted December traffic 3.2 percent to 4.6 million people. The U.K. company has orders and options giving flexibility to operate between 204 and 316 A320- series jets by 2019, compared with about 220 now.

Irish carrier Aer Lingus Group Plc today reported a 3.2 percent increase in full-year traffic, including its regional business, to just over 11 million people. Long-haul passenger numbers were up over 20 percent to 1.3 million, the Dublin-based carrier said in a statement.

Figures for Vueling, the low-cost arm of International Consolidated Airlines Group SA, will be released tomorrow and for Germanwings, part of Lufthansa, on Jan. 12.

Wizz Air Ltd., Eastern Europe’s top discount carrier, said it has set no date as yet for publishing numbers. The Budapest- based company lured 13.5 million passengers in 2013, a 12 percent gain, and 15.5 million in the 12 months to Oct. 31.

–With assistance from Edith Balazs in Budapest.

To contact the reporter on this story: Kari Lundgren in London at klundgren2@bloomberg.net. To contact the editors responsible for this story: Benedikt Kammel at bkammel@bloomberg.net. 

Photo Credit: A Ryanair plane on the tarmac. Ryanair