Narrative:

Cessna 150 in VFR conditions descending from 8;000 ft [in] contact with approach. Approach said to hold at 5;000 ft. After passing the destination airport; approach said to descend at pilot's discretion. Field was at steep slope/angle so pilot changed to rapid descent. Noted some slight engine roughness and engine was not producing full power at this steep angle. The engine was still about 2;400 RPM because of rapid decent. Moving throttle; couldn't notice any difference in power so reported to approach of possible engine problem; throttle was not changing power. Established best glide; moved throttle; full mixture; tried carburetor heat; checked fuel and magnetos. Approach asked if pilot wanted to turn around but had next field in glide. Pilot asked approach to check in case airplane didn't make the field as pilot picked alternate field; but was easily able to make the intended field. Upon landing approach; pilot changed descent angles and engine power was normalized. Approach said to contact them upon ground; but unable on radio so called for tower supervisor by phone. Communication was maintained with all parties. Upon ground check; no debris was found in my fuel filter and both fuel tanks had evidence of fuel; but most likely fuel starvation at a steep angle. Pilot believed near minimum usable fuel with gauges showing good. Steep angle disrupted fuel flow causing engine to miss. Factors are flying too close to minimum usable fuel and assuming fuel gauges are consistent. Pilot [needs] to better understand minimum fuel and affects of steep nose angles with low fuel. Perception was fuel would not ever be an issue. Be more conservative with fuel.

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Original NASA ASRS Text

Title: C150 pilot experiences a rough running engine during steep descent into an airport from 5;000 FT. Pilot elects to divert to a small airport directly ahead and engine begins to run normally as descent rate is shallowed. Minimal fuel is found in the tanks on post flight although the fuel gauges showed sufficient fuel.

Narrative: Cessna 150 in VFR conditions descending from 8;000 FT [in] contact with Approach. Approach said to hold at 5;000 FT. After passing the destination airport; Approach said to descend at pilot's discretion. Field was at steep slope/angle so pilot changed to rapid descent. Noted some slight engine roughness and engine was not producing full power at this steep angle. The engine was still about 2;400 RPM because of rapid decent. Moving throttle; couldn't notice any difference in power so reported to Approach of possible engine problem; throttle was not changing power. Established best glide; moved throttle; full mixture; tried carburetor heat; checked fuel and magnetos. Approach asked if pilot wanted to turn around but had next field in glide. Pilot asked Approach to check in case airplane didn't make the field as pilot picked alternate field; but was easily able to make the intended field. Upon landing approach; pilot changed descent angles and engine power was normalized. Approach said to contact them upon ground; but unable on radio so called for Tower Supervisor by phone. Communication was maintained with all parties. Upon ground check; no debris was found in my fuel filter and both fuel tanks had evidence of fuel; but most likely fuel starvation at a steep angle. Pilot believed near minimum usable fuel with gauges showing good. Steep angle disrupted fuel flow causing engine to miss. Factors are flying too close to minimum usable fuel and assuming fuel gauges are consistent. Pilot [needs] to better understand minimum fuel and affects of steep nose angles with low fuel. Perception was fuel would not ever be an issue. Be more conservative with fuel.

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.