O N A NORMAL Monday morning Terminal 5, Heathrow airport’s busiest, is a hive of activity. Over 100,000 passengers arrive or leave for more than 150 destinations. But on September 9th its departure halls were almost completely abandoned. The only flights taking off were to Cairo, Madrid and Tokyo. The reason was a two-day strike by British Airways ( BA ) pilots and their union, the British Airline Pilots’ Association ( BALPA ). The walkout, which grounded almost 1,700 flights due to carry at least 280,000 people, was the first ever pilot strike at BA . BALPA threatens more—on September 27th and then other dates stretching until January. But far from showing the growing clout of pilots’ unions, their battle for better pay exposes their rapidly weakening position.

At first glance, it would seem that BA ’s pilots have little to complain about. In July they rejected a pay deal which would have increased their salaries by 11.5% over three years—more than average pay in Britain is forecast to rise over the period—and which would have taken the annual pay of a long-haul captain to over £200,000 ($248,000).

But BALPA says its pilots also want a share of BA ’s profits. During the last recession, in 2008-09, its members accepted a 2.6% pay cut and saw some extra allowances slashed when times were tough. So BALPA now says its pilots deserve to benefit from the carrier’s more recent success. After losing £531m in 2010, BA swallowed Aer Lingus, Iberia and Vueling, and since 2014 the combined group, IAG , has made more profit in absolute terms than any other European airline group. IAG ’s announcement in February that it made record profits of €2.9bn ($3.2bn) last year was a red rag to BALPA ’s bulls.