Whatever the action you have envisaged (a team meeting, face-to-face...), the context requires that we know where we are going and with "what" we are going. It is thus necessary to observe the situation attentively (Who expresses what? How? Who is influential?...), to decide upon a strategy (What do we want to obtain? What are the key messages?), and to collect the useful information together beforehand. This is a task which is best done with the help of other interlocutors/supporters (supervisor, RH, peers...).       

One reason for a tense atmosphere: that grievances have not been expressed to the person whom we feel is responsible for the situation (the manager?) or they have not been heard. This is why a first stage is needed to allow the team to express their feelings, and to show to them that they are being heard. This does not indicate that you agree with what has been said but rather that you are capable of understanding the situation from a different point of view.       

Once the grievances have been heard, it becomes possible for you to be heard in your turn. Not to excuse yourself but to accept your proper share of the responsibility and to communicate information that puts the situation in a different light. The information could be objective (a number, a law, an agreement...) or also personal (the guiding principle in a certain decision, a different perception of the situation, a reminder of one's role...). It is ultimately a matter of establishing your position in front of your team.