Narrative:

Company policy is that all training aircraft are to be fueled after a cumulative flight time of two hours and ultimately at the end of the day. Two hours of flight time was put on the training aircraft the previous day and the aircraft was not filled that evening after its last 'after hours' flight was completed. The following morning our second pilot started the preflight on the training aircraft. Before he checked the fuel; one flight canceled and it was decided that I would fly his aircraft. I finished the preflight walk around on his plane; sumped the fuel tanks and climbed on the left wing and checked the fuel level. I did see fuel in the tank however mistook the level as higher than actual. I never checked the right tank as I assumed I had enough fuel in the left tank for the half hour lesson and also assumed the right tank had been filled the previous night.I thus selected the right tank; which I thought was full; and we performed a normal takeoff and climbed out towards our practice area. About 8 minutes into the climb the engine began to run rough and miss and I noticed the fuel pressure reading zero. I selected the left tank; energized the back up fuel pump and the engine restarted and ran normally. After mistaking the level in the left tank I didn't have any concern regarding the fuel status for the remainder of the flight. As a precaution I should have turned back to the airport after the right tank ran dry and double checked my fuel status and filled the tanks. The aerobatic lesson was performed satisfactorily and after we turned back toward the airport. During the descent at around 4;500 ft and 25 miles out the engine started to miss and run rough again. Having already switched tanks I knew that fuel starvation was now a problem. I switched back and forth between the two tanks and the engine intermittently ran for about a minute. I began searching for suitable landing options and after about 30 seconds located a grass strip about four miles west of my position. I estimated the field as a 2;600 ft by 200 ft grass area.I turned toward the strip and began preparing the aircraft for an emergency landing. On short final I extended the flaps and side slipped the aircraft down to a normal touchdown and we rolled out to about three quarters of the length of the field with no damage or injury. We contacted the field owner and we were allowed access by personal vehicle. After fueling the aircraft with 45 gallons of avgas; we performed a soft field take off and made a normal return flight.looking back at the days events I see how important it is to never resume where someone has left off. I should have started the preflight again and covered every aspect. Also it emphasizes the importance of double checking and knowing exactly how much fuel is in the aircraft. I will double check my fuel level no matter how short the flight is or what the object of the flight may be.

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Original NASA ASRS Text

Title: An aerobatics instructor pilot assumed there was enough gas in the large tandem trainer to complete one more training flight; the subsequent landing in a grass field was performed successfully when that wasn't the case.

Narrative: Company policy is that all training aircraft are to be fueled after a cumulative flight time of two hours and ultimately at the end of the day. Two hours of flight time was put on the training aircraft the previous day and the aircraft was not filled that evening after its last 'after hours' flight was completed. The following morning our second pilot started the preflight on the training aircraft. Before he checked the fuel; one flight canceled and it was decided that I would fly his aircraft. I finished the preflight walk around on his plane; sumped the fuel tanks and climbed on the left wing and checked the fuel level. I did see fuel in the tank however mistook the level as higher than actual. I never checked the right tank as I assumed I had enough fuel in the left tank for the half hour lesson and also assumed the right tank had been filled the previous night.I thus selected the right tank; which I thought was full; and we performed a normal takeoff and climbed out towards our practice area. About 8 minutes into the climb the engine began to run rough and miss and I noticed the fuel pressure reading zero. I selected the left tank; energized the back up fuel pump and the engine restarted and ran normally. After mistaking the level in the left tank I didn't have any concern regarding the fuel status for the remainder of the flight. As a precaution I should have turned back to the airport after the right tank ran dry and double checked my fuel status and filled the tanks. The aerobatic lesson was performed satisfactorily and after we turned back toward the airport. During the descent at around 4;500 FT and 25 miles out the engine started to miss and run rough again. Having already switched tanks I knew that fuel starvation was now a problem. I switched back and forth between the two tanks and the engine intermittently ran for about a minute. I began searching for suitable landing options and after about 30 seconds located a grass strip about four miles west of my position. I estimated the field as a 2;600 FT by 200 FT grass area.I turned toward the strip and began preparing the aircraft for an emergency landing. On short final I extended the flaps and side slipped the aircraft down to a normal touchdown and we rolled out to about three quarters of the length of the field with no damage or injury. We contacted the field owner and we were allowed access by personal vehicle. After fueling the aircraft with 45 gallons of Avgas; we performed a soft field take off and made a normal return flight.Looking back at the days events I see how important it is to never resume where someone has left off. I should have started the preflight again and covered every aspect. Also it emphasizes the importance of double checking and knowing exactly how much fuel is in the aircraft. I will double check my fuel level no matter how short the flight is or what the object of the flight may be.

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.