re post 21.
With my knowledge of contracting (admittedly mainly in UK) you can put anything you want in a contract as long as both parties agree (with exception of those deamed penalty clauses or illegal terms). If Seimens has an explicit term relating to risk management, and the recent "incidents" trigger some review, then yes, they may well be able to terminate the contract. Having said that, I doubt the contract is with Ryanair directly, probably with a "Travel Agency / consultant" as stated in a post above.
What is interesting is why they chose to go public (if indeed it was choice). Contracts are generally not discussed outside of the 2 parties.