Ace Combat 5 - Mission 11B: Reprisal (Ace - S Rank)

If you've answered No to Chopper's question at the start of Mission 10, you'll get tasked with spreading neutralising gas around Bana City to combat a chemical attack. The S Rank for this mission is completely time-based, so don't dawdle. After that, you'll have to follow a truck and can optionally shoot at stuff it drops for 10 points per item, but again, that has no bearing on the S Rank. Finally, you'll have to take down helicopters using your guns, nothing too complicated overall.