Narrative:

I departed for a 2-1/2 hr flight with three passengers. Preflight plan was to depart with full fuel minus 100 lbs to ensure departure weight less than maximum gross. Fuel capacity is 92 gals; which meant approx 75 gals was needed. The evening before the this flight; I fueled up with intention to make 3 landings to full stop at night and perform a VOR check and land with 75 gallons remaining. Based on the previous fill-up date and flights made since; I calculated that I had 37 gallons and needed 38 gallons for my goal plus an addition 10 gallons for the night flight. I began filling the right tank and noticed that the tank was nearly full after only 14 gallons were put in tank. I decided that I made a mistake in my calculations and removed 24 gallons from my intended fill amount. 24 gallons was the amount used on a 2 hr flight earlier in the week just after my last fill up; but now my doubts about fuel used made me think this flight was made before the last fill up and not after. I put in 10 more gallons in the left tank. The level of the fuel in the left tank was a couple inches below the opening so I was satisfied I had the right amount of fuel. I departed as planned. Approx 1.5 - 2 hrs into the flight I noticed the fuel gauges showing the left tank had about 1/8 more than the right tank. I think the levels were 3/8 showing in the left tank and 1/4 on the right. I considered that overall; the fuel levels shown were too low for what what it should be; but the plane was new to me and this was the first cross-country flight made in this plane; so I dismissed the signs of low fuel to inaccurate gauges and focused on the difference between the two. I switched the fuel selector to the left tank thinking I would draw fuel from the left tank and even things up.after that; I forgot about the fuel valve position. 2 1/2 hours into the flight and flying right by an air force base I experienced total loss of engine power. I immediately turned on the carb heat which returned engine power for a few seconds; but then lost power again. Aware that the airfield off my left wing was in easy reach; I abandoned troubleshooting the problem and focused all attention on aligning the plane for a power off landing. I declared an emergency to approach and reported intentions to land. I contacted the field tower and was given clearance to land. Landing was made halfway down the runway with no issues. As soon as I touched down; I remembered the fuel valve that I switched to the left tank. I switched the valve to the right tank and restarted the engine and taxied to the ramp. After parking; I visually checked the fuel levels. The left tank was empty and the right tank was only a couple inches full. Later in the day; I filled up with 75 gallons indicating I landed with only 17 gallons. Calculating 30 gallons used on the trip meant I only had 47 gallons - enough for 4 hrs; instead of the 72; or 6 hrs to make the trip. Mistakes made and lessons learned: I didn't have a verifiable way of determining exactly the amount of fuel on board before taking off. I made correct calculations; but doubted them partway through the fueling process and made changes that shouldn't have been made. This resulted in flying with 25 gallons less than I thought. There was no good reason to switch the fuel valve to one tank. Forgetting about it made things worse. My fuel gauges are not nearly as inaccurate as I thought.

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Original NASA ASRS Text

Title: A C182 pilot made poor fuel-on-board calculations; optimistic risk assessment and poor fuel management techniques which resulted in an engine failure and emergency landing despite 17 gallons of fuel remaining.

Narrative: I departed for a 2-1/2 hr flight with three passengers. Preflight plan was to depart with full fuel minus 100 lbs to ensure departure weight less than maximum gross. Fuel capacity is 92 gals; which meant approx 75 gals was needed. The evening before the this flight; I fueled up with intention to make 3 landings to full stop at night and perform a VOR check and land with 75 gallons remaining. Based on the previous fill-up date and flights made since; I calculated that I had 37 gallons and needed 38 gallons for my goal plus an addition 10 gallons for the night flight. I began filling the right tank and noticed that the tank was nearly full after only 14 gallons were put in tank. I decided that I made a mistake in my calculations and removed 24 gallons from my intended fill amount. 24 gallons was the amount used on a 2 hr flight earlier in the week just after my last fill up; but now my doubts about fuel used made me think this flight was made before the last fill up and not after. I put in 10 more gallons in the left tank. The level of the fuel in the left tank was a couple inches below the opening so I was satisfied I had the right amount of fuel. I departed as planned. approx 1.5 - 2 hrs into the flight I noticed the fuel gauges showing the left tank had about 1/8 more than the right tank. I think the levels were 3/8 showing in the left tank and 1/4 on the right. I considered that overall; the fuel levels shown were too low for what what it should be; but the plane was new to me and this was the first cross-country flight made in this plane; so I dismissed the signs of low fuel to inaccurate gauges and focused on the difference between the two. I switched the fuel selector to the left tank thinking I would draw fuel from the left tank and even things up.After that; I forgot about the fuel valve position. 2 1/2 hours into the flight and flying right by an Air Force Base I experienced total loss of engine power. I immediately turned on the carb heat which returned engine power for a few seconds; but then lost power again. Aware that the airfield off my left wing was in easy reach; I abandoned troubleshooting the problem and focused all attention on aligning the plane for a power off landing. I declared an emergency to Approach and reported intentions to land. I contacted the field Tower and was given clearance to land. Landing was made halfway down the runway with no issues. As soon as I touched down; I remembered the fuel valve that I switched to the left tank. I switched the valve to the right tank and restarted the engine and taxied to the ramp. After parking; I visually checked the fuel levels. The left tank was empty and the right tank was only a couple inches full. Later in the day; I filled up with 75 gallons indicating I landed with only 17 gallons. Calculating 30 gallons used on the trip meant I only had 47 gallons - enough for 4 hrs; instead of the 72; or 6 hrs to make the trip. Mistakes made and lessons learned: I didn't have a verifiable way of determining exactly the amount of fuel on board before taking off. I made correct calculations; but doubted them partway through the fueling process and made changes that shouldn't have been made. This resulted in flying with 25 gallons less than I thought. There was no good reason to switch the fuel valve to one tank. Forgetting about it made things worse. My fuel gauges are not nearly as inaccurate as I thought.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.