Narrative:

As I was descending to tpa after cross country; I descended in steps from 9500 ft. From 5500 ft to 2800 ft I descended rather steeply to get to tpa before I started the 3 mi 45 degrees. As I rounded out from the descent the engine started to miss. A steady dum; dum; dum; like a fouled plug; or loose plug wire or perhaps a magnetic; I applied throttle and it took the throttle smoothly with no hesitation or sputter; but it still had the steady miss. It would take full power and accelerate with no hesitation. I entered the pattern and landed. After taxiing to the tie-downs and during magnetic ground check; I shut down. The briefing had called for 20 KT headwinds but during the later part of the flight my check points were late. I recalculated the time and fuel and felt I had enough. After filling the tanks (47 gals/50 gal tank) I said that as I arrived at the field I had had approximately 30 mins of fuel. The chief flight instructor; who had given me my check ride and progressive checks when I was a student said I should have used even more conservative mileage figures to plan than I did. I told him that neither he nor the instructor had ever mentioned figures other than the poh numbers. It would be a good idea for instructors to tell students and new pilots that the planes don't get the gph or TAS listed; especially the older planes.

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Original NASA ASRS Text

Title: ROUGH ENGINE RUN ON FINAL FOLLOWING A LONG CROSS COUNTRY ALERTS INEXPERIENCED PRIVATE PLT TO NEAR FUEL EXHAUSTION. DISCOVERS ONLY THREE GALLONS OF FUEL LEFT IN THE C172 AFTER REFUELING.

Narrative: AS I WAS DSNDING TO TPA AFTER XCOUNTRY; I DSNDED IN STEPS FROM 9500 FT. FROM 5500 FT TO 2800 FT I DSNDED RATHER STEEPLY TO GET TO TPA BEFORE I STARTED THE 3 MI 45 DEGS. AS I ROUNDED OUT FROM THE DSCNT THE ENG STARTED TO MISS. A STEADY DUM; DUM; DUM; LIKE A FOULED PLUG; OR LOOSE PLUG WIRE OR PERHAPS A MAG; I APPLIED THROTTLE AND IT TOOK THE THROTTLE SMOOTHLY WITH NO HESITATION OR SPUTTER; BUT IT STILL HAD THE STEADY MISS. IT WOULD TAKE FULL PWR AND ACCELERATE WITH NO HESITATION. I ENTERED THE PATTERN AND LANDED. AFTER TAXIING TO THE TIE-DOWNS AND DURING MAG GND CHK; I SHUT DOWN. THE BRIEFING HAD CALLED FOR 20 KT HEADWINDS BUT DURING THE LATER PART OF THE FLT MY CHK POINTS WERE LATE. I RECALCULATED THE TIME AND FUEL AND FELT I HAD ENOUGH. AFTER FILLING THE TANKS (47 GALS/50 GAL TANK) I SAID THAT AS I ARRIVED AT THE FIELD I HAD HAD APPROX 30 MINS OF FUEL. THE CHIEF FLT INSTRUCTOR; WHO HAD GIVEN ME MY CHK RIDE AND PROGRESSIVE CHKS WHEN I WAS A STUDENT SAID I SHOULD HAVE USED EVEN MORE CONSERVATIVE MILEAGE FIGURES TO PLAN THAN I DID. I TOLD HIM THAT NEITHER HE NOR THE INSTRUCTOR HAD EVER MENTIONED FIGURES OTHER THAN THE POH NUMBERS. IT WOULD BE A GOOD IDEA FOR INSTRUCTORS TO TELL STUDENTS AND NEW PLTS THAT THE PLANES DON'T GET THE GPH OR TAS LISTED; ESPECIALLY THE OLDER PLANES.

Data retrieved from NASA's ASRS site as of January 2009 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.