No formal charges yet, that comes later in the process, once they are 'acusados' for a formal trial.
Currently they are only 'imputados', i.e. there are 'reasonable reasons' to believe that these persons could be directly connected to a criminal event.
On the other hand, being 'imputados' gives them additional procedural rights which they do not have when they are mere 'witnesses': you do not have to testify against yourself, you hav eaccess to all of the data in the judges possession...which in one sense may be better for them.
The funny thing is that the judge actually based his connection to call them 'imputados' on non-official details coming from the CIAIAC investigation...which is clearly against Annex 13 and the EU directive on accident investigation...which call for separate judicial and aviation investigations.
The judge's commission, however, has not officially been created as a result of this requirement ?!! but as a result of his desire to speed things up...