Narrative:

We went to training approximately XA30. I initially left from 2w5 and flew for 30 mins. We anticipated that we still had 3 hours of fuel on board (with 30 mins reserve) since we had 21 gallons usable and I used 5.5 gallons on my first leg. However, on the way back to hef around XA50, we heard a noise and my instructor, who was flying at the time, sensed that we were running out of fuel. He immediately found this farm land to land, and we executed an emergency landing. We got fuel there and took off. I think he made a perfect choice since we were about to go over a hill. Supplemental information from acn 536802: at approximately XA15, we began an instrument training flight in VMC from hef to mrb and back, planning to do multiple practice approachs at mrb. Prior to the first approach at mrb, we were given instructions to hold at the mrb VOR. Prior to the flight, the student told me that the tanks were full prior to her departure from maryland airport (2w5) and that her flight took 22 mins. I verified full fuel indications on the gauges and nearly full fuel levels in the tanks. I calculated that at a fuel burn of 5.5 gph and 21.5 gallons of usable fuel we had about 3 hours 54 mins endurance. This would allow us to stay up until XD15 with a 30 min reserve. The 25 mins of holding over mrb would have reduced that endurance time. At about XC50 while about 20 NM from hef, the engine momentarily sputtered and I decided to make a precautionary landing in an open field, suspecting an impending fuel starvation. On landing, we checked the fuel level and found small amounts of fuel remaining in each tank. We put 10 gallons in the plane, got the owner's permission, and departed the field for manassas.

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Original NASA ASRS Text

Title: A C150 INSTRUCTOR AND STUDENT MISCALCULATED THEIR FUEL BURN, REQUIRING A PRECAUTIONARY LNDG IN A FIELD.

Narrative: WE WENT TO TRAINING APPROX XA30. I INITIALLY LEFT FROM 2W5 AND FLEW FOR 30 MINS. WE ANTICIPATED THAT WE STILL HAD 3 HRS OF FUEL ON BOARD (WITH 30 MINS RESERVE) SINCE WE HAD 21 GALLONS USABLE AND I USED 5.5 GALLONS ON MY FIRST LEG. HOWEVER, ON THE WAY BACK TO HEF AROUND XA50, WE HEARD A NOISE AND MY INSTRUCTOR, WHO WAS FLYING AT THE TIME, SENSED THAT WE WERE RUNNING OUT OF FUEL. HE IMMEDIATELY FOUND THIS FARM LAND TO LAND, AND WE EXECUTED AN EMER LNDG. WE GOT FUEL THERE AND TOOK OFF. I THINK HE MADE A PERFECT CHOICE SINCE WE WERE ABOUT TO GO OVER A HILL. SUPPLEMENTAL INFO FROM ACN 536802: AT APPROX XA15, WE BEGAN AN INST TRAINING FLT IN VMC FROM HEF TO MRB AND BACK, PLANNING TO DO MULTIPLE PRACTICE APCHS AT MRB. PRIOR TO THE FIRST APCH AT MRB, WE WERE GIVEN INSTRUCTIONS TO HOLD AT THE MRB VOR. PRIOR TO THE FLT, THE STUDENT TOLD ME THAT THE TANKS WERE FULL PRIOR TO HER DEP FROM MARYLAND ARPT (2W5) AND THAT HER FLT TOOK 22 MINS. I VERIFIED FULL FUEL INDICATIONS ON THE GAUGES AND NEARLY FULL FUEL LEVELS IN THE TANKS. I CALCULATED THAT AT A FUEL BURN OF 5.5 GPH AND 21.5 GALLONS OF USABLE FUEL WE HAD ABOUT 3 HRS 54 MINS ENDURANCE. THIS WOULD ALLOW US TO STAY UP UNTIL XD15 WITH A 30 MIN RESERVE. THE 25 MINS OF HOLDING OVER MRB WOULD HAVE REDUCED THAT ENDURANCE TIME. AT ABOUT XC50 WHILE ABOUT 20 NM FROM HEF, THE ENG MOMENTARILY SPUTTERED AND I DECIDED TO MAKE A PRECAUTIONARY LNDG IN AN OPEN FIELD, SUSPECTING AN IMPENDING FUEL STARVATION. ON LNDG, WE CHKED THE FUEL LEVEL AND FOUND SMALL AMOUNTS OF FUEL REMAINING IN EACH TANK. WE PUT 10 GALLONS IN THE PLANE, GOT THE OWNER'S PERMISSION, AND DEPARTED THE FIELD FOR MANASSAS.

Data retrieved from NASA's ASRS site as of July 2007 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.