Yes, you can, and should, contact the prosecutor and notify them that you have a prearranged trip planned that is going to take you out of state at that time. Do not call the court, the court is not going to address your concerns. Whether or not the prosecutor will reset the hearing will depend on how cooperative the defendant and his attorney and the court are willing to be; if the defense will not stipulate to an adjournment or the court won't grant the adjournment then the options get limited. 1. The prosecutor can ask for a bench warrant for you for not showing up despite having been served, (this is probably not very likely since the state doesn't want to be arresting its' own witnesses). 2. You can change your plans, and simply make yourself available. 3. The prosecution can dismiss the charges without prejudice; this would mean they would be able to refile the charges.