Narrative:

I was assigned to fly route in a 1969 small aircraft X (see copy of route card). Conducted under VFR the route has a morning departure from phx with stops at prescott, kingman and bullhead city, with an evening return in reverse order. On previous day I had refueled at kingman, tach 1135.9. On the day in question engine start for departure from phx was at tach 1138.3. I arrived in prescott at tach 1139.1, and unloaded the prescott freight. In prescott I decided that a direct route between prescott and kingman was not possible due to deteriorating WX conditions. I calculated fuel remaining and arrived at a figure of 45.8 gals of usable fuel. This was enough fuel for a little more than 3 hours of flight at normal consumption, however I made a computational error which skewed my fuel remaining figures. See back of route card. The poh states an endurance of approximately 6 hours at the altitudes I planned to use. This agreed with my figures. After takeoff, I called prescott unicom and requested that they call company and report that I would be at least a 1/2 hour late at kingman. I elected to run only the right tank and time to its depletion, since both gauges indicated approximately the same amount of fuel remaining. Abeam wickenburg, time unknown, I called another company aircraft and asked them to notify the company that I would bypass kingman and go to bullhead city. The right tank ran dry when I was abeam lake havasu and checked fuel remaining. I knew I was now 25 mins from bullhead city, because of previous trip times. I figured fuel reserve of 35 mins on landing at bullhead city. I began to feel a continuous vibration from the engine. I ran an emergency procedure for rough engine, and since it did not help decided the most prudent action was to land immediately. I selected a straight n-s running gravel road with no people, traffic or bldgs along its length. It was also aligned with the prevailing winds. I flew downwind, verified no traffic, reduced power and set 10 degrees of approach flaps and slowed to 90 mph. On final I realized I would land long, so I pulled power and set 30 degrees of flaps. After landing I secured the aircraft, tach 1141.3. I walked to mohave valley, az and called company. Later the courier for the company arrived to pick up the freight. She gave me 10 gals of 100 ll AVGAS which I strained into the right fuel tank. I preflted the aircraft and used a car to drive the length of the road to check for obstacles. I positioned a pilot at the end of the road, well clear of my takeoff path, to flag any chance traffic. I started the end and checked for proper operation. I began my takeoff roll and landed bullhead city, tach 1142.5. Recommendations: carry enough money so that at least 1 hour of fuel can be purchased. On the back of the next day's route card, record each tank's use so that an exact record of fuel consumed will be at hand. Change refuel from the morning stop to the evening stop in kingman. This step alone gives nearly an extra hour of fuel to the pilot.

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Original NASA ASRS Text

Title: ATX PLT MAKES MATH ERRORS IN FUEL MANAGEMENT CALCULATIONS, SUFFERS FUEL EXHAUSTION AND MAKES FORCED LNDG OFF ARPT.

Narrative: I WAS ASSIGNED TO FLY RTE IN A 1969 SMA X (SEE COPY OF RTE CARD). CONDUCTED UNDER VFR THE RTE HAS A MORNING DEP FROM PHX WITH STOPS AT PRESCOTT, KINGMAN AND BULLHEAD CITY, WITH AN EVENING RETURN IN REVERSE ORDER. ON PREVIOUS DAY I HAD REFUELED AT KINGMAN, TACH 1135.9. ON THE DAY IN QUESTION ENG START FOR DEP FROM PHX WAS AT TACH 1138.3. I ARRIVED IN PRESCOTT AT TACH 1139.1, AND UNLOADED THE PRESCOTT FREIGHT. IN PRESCOTT I DECIDED THAT A DIRECT RTE BTWN PRESCOTT AND KINGMAN WAS NOT POSSIBLE DUE TO DETERIORATING WX CONDITIONS. I CALCULATED FUEL REMAINING AND ARRIVED AT A FIGURE OF 45.8 GALS OF USABLE FUEL. THIS WAS ENOUGH FUEL FOR A LITTLE MORE THAN 3 HRS OF FLT AT NORMAL CONSUMPTION, HOWEVER I MADE A COMPUTATIONAL ERROR WHICH SKEWED MY FUEL REMAINING FIGURES. SEE BACK OF RTE CARD. THE POH STATES AN ENDURANCE OF APPROX 6 HRS AT THE ALTS I PLANNED TO USE. THIS AGREED WITH MY FIGURES. AFTER TKOF, I CALLED PRESCOTT UNICOM AND REQUESTED THAT THEY CALL COMPANY AND RPT THAT I WOULD BE AT LEAST A 1/2 HR LATE AT KINGMAN. I ELECTED TO RUN ONLY THE RIGHT TANK AND TIME TO ITS DEPLETION, SINCE BOTH GAUGES INDICATED APPROX THE SAME AMOUNT OF FUEL REMAINING. ABEAM WICKENBURG, TIME UNKNOWN, I CALLED ANOTHER COMPANY ACFT AND ASKED THEM TO NOTIFY THE COMPANY THAT I WOULD BYPASS KINGMAN AND GO TO BULLHEAD CITY. THE RIGHT TANK RAN DRY WHEN I WAS ABEAM LAKE HAVASU AND CHKED FUEL REMAINING. I KNEW I WAS NOW 25 MINS FROM BULLHEAD CITY, BECAUSE OF PREVIOUS TRIP TIMES. I FIGURED FUEL RESERVE OF 35 MINS ON LNDG AT BULLHEAD CITY. I BEGAN TO FEEL A CONTINUOUS VIBRATION FROM THE ENG. I RAN AN EMER PROC FOR ROUGH ENG, AND SINCE IT DID NOT HELP DECIDED THE MOST PRUDENT ACTION WAS TO LAND IMMEDIATELY. I SELECTED A STRAIGHT N-S RUNNING GRAVEL ROAD WITH NO PEOPLE, TFC OR BLDGS ALONG ITS LENGTH. IT WAS ALSO ALIGNED WITH THE PREVAILING WINDS. I FLEW DOWNWIND, VERIFIED NO TFC, REDUCED PWR AND SET 10 DEGS OF APCH FLAPS AND SLOWED TO 90 MPH. ON FINAL I REALIZED I WOULD LAND LONG, SO I PULLED PWR AND SET 30 DEGS OF FLAPS. AFTER LNDG I SECURED THE ACFT, TACH 1141.3. I WALKED TO MOHAVE VALLEY, AZ AND CALLED COMPANY. LATER THE COURIER FOR THE COMPANY ARRIVED TO PICK UP THE FREIGHT. SHE GAVE ME 10 GALS OF 100 LL AVGAS WHICH I STRAINED INTO THE RIGHT FUEL TANK. I PREFLTED THE ACFT AND USED A CAR TO DRIVE THE LENGTH OF THE ROAD TO CHK FOR OBSTACLES. I POSITIONED A PLT AT THE END OF THE ROAD, WELL CLR OF MY TKOF PATH, TO FLAG ANY CHANCE TFC. I STARTED THE END AND CHKED FOR PROPER OPERATION. I BEGAN MY TKOF ROLL AND LANDED BULLHEAD CITY, TACH 1142.5. RECOMMENDATIONS: CARRY ENOUGH MONEY SO THAT AT LEAST 1 HR OF FUEL CAN BE PURCHASED. ON THE BACK OF THE NEXT DAY'S RTE CARD, RECORD EACH TANK'S USE SO THAT AN EXACT RECORD OF FUEL CONSUMED WILL BE AT HAND. CHANGE REFUEL FROM THE MORNING STOP TO THE EVENING STOP IN KINGMAN. THIS STEP ALONE GIVES NEARLY AN EXTRA HR OF FUEL TO THE PLT.

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.