Checklists: Why do I Need To Use Them?

As you go through your flying career, whatever flying from GA to Part 121, there is always the checklist! Some pilots have said "I've owned my plane for years and have everything memorized." Or the Part 135 pilot that had a great career with a major and now flies smaller planes and feels they don't really need a check list every time. What if you are at a busy airport and there are planes lined up behind you? You just flew last week, you feel like you remember it well.

Yes, you do, but how do you behave in an emergency? What happens to your memory when an engine quits or a fire starts? Are you...