Lufthansa subsidiary Swiss International Air Lines reported an operating loss of 4 million francs ($4.39 million) in the first quarter of 2012, compared with last year's operating profit of 16 million francs.
Its total operating income for the three months ending 31 March grew 2% to 1.17 billion francs, compared with 1.15 billion francs in the same period the year before.
The airline's passenger numbers rose by 5.1% year-on-year to 3.61 million.
Traffic for the quarter grew 4.5% year-on-year against a capacity increase of 2.6%, leading to a load factor for the period of 77.8% - up 1.4 percentage points.
Load factors at Swiss WorldCargo stood at 80.5%, down from 81.1% posted in the first quarter of 2011.
Swiss chief executive Harry Hohmeister says: "We see no sign at present of any imminent market recovery. And fuel prices and currency movements, too, are unlikely to offer us any better prospects any time soon."