Unplanned often implies stress or surprise as people might not be ready to handle it. Their reactions to the unplanned news were a mix of shock and confusion.
Pro Tip 2/3
Context Sensitive
The impact of 'unplanned' varies greatly with context—exciting in travels, worrying in finances. We had an unplanned adventure when we discovered a hidden beach.
Pro Tip 3/3
Negative Implications
Unplanned often has a negative connotation, suggesting poor organization or problems. The unplanned outage caused trouble for thousands of users.