Error Message Information
Due to the permissions system as it is in SL, and the messaging setup you may get error messages from the aircraft when a co-pilot sits and when you sit without a co-pilot. These messages have to do with the scripts looking for an avatar in the sit position and when there is not one, the script sends a message to the owner of the aircraft. It is nothing to be concerned about, and the aircraft will operate perfectly well and as it was designed to.
One way to eliminate this issue is to disable error messages in your viewer. Each viewer has this option in the preferences area, and each viewer may have slightly differing menus so it would be hard to explain how to do that here. However if you look through your settings in the viewer, you should be able to disable the error messages and not see them at all.