Pilot’s intuition
We’re only guessing that as a pilot, experience plays a tremendous role in the safety of your passengers and aircraft. We’ve never really heard of a plane being unbalanced, but then again, we’re not pilots. Well, the OP in this story and his co-pilot realized something was wrong before taking off.
While taxiing the plane down the road, they realized that the plane’s center of gravity was out of whack. After further inspection, they discovered that the plane’s ballast, a device that adds stability to counterbalance overweight issues, wasn’t even on the plane! If they had lifted off without it, the plane would have come crashing back down onto the runway.