FlyNiki partner Air Berlin had around six per cent more customers in the first five months of this year than in the same period of 2010.The carrier which has been cooperating with Vienna-based FlyNiki since 2004 said yesterday (Mon) it recorded 12.95 passengers between January and May 2011. Air Berlin said this was a 6.3 improvement compared to the same time span of last year. Air Berlin added that 74.1 per cent of offered tickets were sold in the first five months of 2011, up by 2.6 per cent.Air Berlin announced some weeks ago that it suffered a loss of 9.3 million Euros before interest and taxes last year. The firm added that it had a turnover of 3.72 billion Euros at the same time.Air Berlin had 33.6 million passengers in 2010. With around 8,000 employees, Air Berlin is Germanys second-largest airline after Lufthansa, the main shareholder of Austrian Airlines (AUA).Meanwhile, the stocks of some of the worlds leading carriers suffered in value yesterday after the International Air Transport Association (IATA) said airlines will make a profit of four billion US dollars (2.7 billion Euros) this year. Shareholders and traders showed a sense of nervousness as the global aviation trade group previously predicted a global turnover of 8.6 billion US dollars (5.9 million Euros).Experts have said some airlines could go bankrupt this year due to soaring kerosene prices, less demand from Japan after the tsunami in March and the civil war-like developments in North Africa and some Arab countries.Air Berlin and FlyNiki are operating at Vienna International Airport (VIA or VIE) and several other aerodromes in Austria. AUA is one of the carriers main rivals. The struggling airlines pilots were angered when it emerged last week that it paid bonuses of three million Euros to 150 managers in 2010 when AUA suffered a loss of almost 65 million Euros.