Talking about fuel, reminds me of three occasions.
1) When doing a check ride during PPL training, at the holding point and AFTER completing the pre take-off checks, the instructor asked what would I do if there was a fire. I mutter about switching off the fuel, which he then DID, to demonstrate that it didn't achieve much. We talked through the correct actions, and then took off. At about 500ft, I saw him slip his hand down and turn ON the fuel cock.
2) Having completed some revision training, I was given the aircraft at the end of a busy day and told to get myself another half hours time. The fuel guages showed 1/4 full, so off I went just a little way out of the circuit for some turns and stalls. Climbing away, I glanced at the fuel guages, which are on their stops, showing completely empty. PANIC, and that writhing snake in the bowels! I shove the nose down and wheel it back to the airfield. The guages are now showing 1/4 full again. On a climb the fuel slops to the back of the tanks, away from the fuel guage, especially with only little fuel on board. Not intrinsically dangerous but it scared the
out of me.
3) Check out on a local club C150, but I only had C172 checklist. I came to the bit about selecting both tanks, but since the C150 doesn't have a tank selector, I SKIPPED over this check. Later, musing over the flight, I realised I hadn't checked the fuel turned ON (instead of both tanks selected). Fortunately, the club always leaves the fuel selector ON.
So easy to screw up ....
GB