… offers you only a seasonal position  
... wants you to sign a contract with an agency rather than directly with them  
... offers you training but with strings attached (payment, bonds...) 
... assigns you a 'tick in the box' Home Base or expects you to ‘float’ around to where they need you 
... guarantees less salary than your local supermarket would 
... asks you to work for them as ‘self-employed’ pilot 
… asks you to open a Swiss bank account 
… doesn’t transparently discuss your salary elements 
… wants you to sign a document waving your right to join a union 
… doesn’t want you to have a lawyer look at the employment contract 
… offers a contract which allows them to put you on unpaid leave for a very, very long time 
…  has safety culture which has come into question 
... counts your sick days as rest days  

Before you sign a contract, make sure you understand what kind of employment relationship you’re getting into!