Understand that what they recieve 'tax free' has already had tax paid on it before it reaches them. Based on paying the German income tax rate at the highest level at 52% 30,000 euro 'take home' equates to 63,000 euro Gross.
Take the 63,000 add to the basic and you have a total gross salary of 123,000 Euro in year one.
At least thats how I presume Ryanair do their figures when enticing crew and you can do the same when it comes to applying for finances/mortgage etc.