Crew sickness is not an extraordinary circumstance. Sick staff is normal for an airline. It's their risk.
Perhaps in the EU. Not likely in Switzerland.
Even in the EU that is a far-fetched concept for a carrier not based at ZRH.
I am not an expert on some precedent in Swiss law.
However, I'd be quite surprised why a Swiss court would issue a completely different verdict than a German (EU) court would do.
Staff sickness is an issue each transportation provider (e.g. bus, train, ship, metro) has to deal with. It is a completely common thing that people get sick. Each company has procedures in place to solve problems arising from sick calls.
-> There is nothing extraordinary in the fact that one crew member gets sick.
As far as I always understood, Force Majeur is a major event completely out of control of the parties - natural disaster, terrorist attack, bad weather etc. Other things I can think of like a labor strike or airport running out of de-icing fluid during the winter (happened to me years ago). That's outside of the airline's control.
Well, I wouldn't agree with that. There can be event that are outside the control of the airline, but are not extraordinary regarding EC261/2004. If an event happens many times during a year, it is not extraordinary anymore.
e.g.:
- normal snow activity in HEL in the winter
- normal thunderstorm activity in SIN
- screw-ups by a provider
- continuous ATC delays (which happen very often and can be predicted)
In Swiss court of law I would ask EK how often do they experience crew sickness. EK will most likely refuse to share any numbers. However, that means EK has no chance in proving the extraordinary nature of that event.