To become an Air traffic Controller, all you need is a “fin d’études secondaires” diploma or an equivalent diploma.
You can find out if there are any vacancies on this homepage of the government.
You have to pass a classification exam including a psychological and a medical test.
Successfully passed this test, you will start your training at the DFS (Deutsche Flugsicherung) in Langen (a few kilometers away from Frankfurt am Main) where you will acquire the necessary theoretical and practical skills to start your on-the-job training in Luxembourg. The training in Langen will last 9-12 months. During these months accommodation will be provided either in the academy of the DFS or in a hotel nearby.
Back in Luxembourg you have to pass your practical on-the-job training in Luxembourg which will last for about 18 months.
As you will be recruited as a pubic servant, the last step to become an air traffic controller is to pass a final written an oral exam (examen de fin de stage).