Simon Sommer of cancelled.ch was recently allowed to explain in a observer article why such chaotic conditions occurred at European airports this summer.
One of the main reasons for this is the massive passenger growth that has been going on for years. There are more flights than ever before. This is pushing the airlines and the entire infrastructure to their limits. In the meantime, the first airlines are even hoping that there will be fewer aircraft in the air. That sounds strange at first. But Lufthansa CEO Carsten Spohr recently stated that everything has become even worse than he thought and that a reduction in flight movements could counteract the massive increase in delays.
The airport infrastructure is at a standstill in many places and expansion is not always possible. At Zurich Airport, for example, so-called slots are in great demand. This means that airlines can hardly obtain new slots in which an aircraft can land or take off. A timely expansion of the airport is unrealistic for many reasons. And so the side effects associated with the steady growth (cancellations, delays, denied boarding) will probably have to be accepted until further notice. The consequences are angry passengers, but also angry crews and employees.
An example of this can be heard in the following audio clip, in the second part in Swiss German. The language is rather coarse, but the annoyance of the pilot demonstratively stands for numerous problems, with which the customers of cancelled.ch were confronted in the past (and partly presumably, understandably, also cursed about it).