Fuel Selector Confusion on Approach

Departing Clearwater Air Park (KCLW), Clearwater, FL — Runway 16, a local flight to practice approaches and landings. Elevation 71 ft MSL. The field is non-towered (CTAF 122.8); you are in Class G airspace below 3,000 ft MSL. Above 3,000 ft MSL, you enter the overlying Tampa Class B airspace (3,000 MSL → 10,000 MSL).

It is a clear, calm morning: OAT 22°C, winds calm to 3 kt, altimeter 30.01. Visibility 10 SM. A routine VFR training flight. You plan to climb to 2,500 ft AGL (roughly 2,570 ft MSL), practice two or three approaches to Runway 16, and land.

Aircraft: Cessna 172N, solo, full fuel at departure (53 gallons usable). Lycoming O-320, carbureted, fixed-pitch prop, fuel selector on BOTH. The airplane was airworthy at preflight; nothing was written up. You did a standard preflight and confirmed both tanks full.

Pilot: you — a Private pilot, current, roughly 180 hours total. You are familiar with KCLW; you trained here. You have flown this airplane a dozen times. The fuel selector on the C172N is a three-position lever: LEFT, BOTH, RIGHT. You know this intellectually, but you have not had to think about it much — BOTH has been the default.

The flight: You depart Runway 16 at 0900 local, climb to 2,500 ft AGL, and practice two approaches. The first approach is a go-around (you were high). The second approach is a touch-and-go landing. You are now back at 2,500 ft AGL, heading 155° (downwind for Runway 16), ready for a third approach. Total flight time so far: 45 minutes. Fuel remaining: approximately 35–40 gallons (roughly 4.5–5 hours endurance at cruise power).

At 2,500 ft AGL on downwind, you begin the descent for the third approach. The engine is running smoothly. You are heads-down on the approach briefing. You do not notice that your hand has bumped the fuel selector lever — it is now on LEFT, not BOTH. The left tank has been feeding the engine for the last 45 minutes of flight. The left tank is nearly empty.

NTSB NYC06LA179 (2006, fatal): A Cessna 172N on a personal local flight experienced partial loss of engine power during cruise due to improper maintenance of the throttle shaft during the most recent annual inspection. The pilot made a forced landing that resulted in collision with trees. The probable cause was improper maintenance of the throttle shaft, which resulted in a partial loss of engine power during cruise flight.

NTSB CHI02FA247 (2002, fatal): A Cessna 172N on a night personal flight from Minnesota to Wisconsin experienced fuel exhaustion during final approach. The pilot failed to refuel before departure and did not plan fuel adequately. The airplane was forced to land in a cornfield. The probable cause was the pilot's failure to refuel prior to departure, inadequate preflight/inflight planning, and unsuitable terrain encountered during the forced landing attempt. Contributing factors included pilot fatigue and night conditions.

NTSB CEN25LA168 (2025): A Cessna 172N on an instructional flight lost engine power on final approach when the throttle cable was found disconnected from the carburetor. The pilot executed a forced landing to a field. The accident resulted from improper maintenance following carburetor replacement, with an apprentice's work not adequately inspected by the supervising mechanic.

NTSB CEN25LA099 (2025): A Cessna 172N on a cross-country flight lost total engine power during a go-around after an aborted landing due to fuel exhaustion. The pilot made poor flight-planning decisions and did not refuel at an intermediate stop despite instructor guidance. The probable cause was poor flight planning and decision making, which resulted in a loss of engine power due to fuel exhaustion.

NTSB WPR24LA167 (2024): A Canadian Car & Foundry Harvard MK IV lost all engine power due to fuel starvation when the pilot improperly selected the left fuel tank at low fuel levels. The accident resulted from improper fuel tank selection and a malfunctioning fuel selector, requiring a forced landing that struck a dirt berm.

NTSB GAA19CA534 (2019): A Piper PA-28 lost engine power during descent to land after the pilot switched to the left fuel tank and failed to follow the emergency power loss checklist. The accident resulted from improper fuel management and failure to switch to the right tank containing usable fuel, leading to fuel starvation and a forced landing on a road.

The common thread: fuel starvation from improper tank selection or fuel exhaustion from inadequate planning. In the C172N, the fuel selector is a three-position lever: LEFT, BOTH, RIGHT. BOTH is the normal cruise and approach position. Switching to a single tank should be deliberate and for a specific reason. Complacency — assuming the selector is where you left it — is the trap. The real accidents cited above occurred at other airports and in other aircraft — NOT at KCLW. This scenario is localized to KCLW to make the off-field environment real and consequential for you as a student here. Off Runway 16 at KCLW, the off-field environment is dense development — a forced landing there is a landing in a developed area, not a field landing.

The lesson is simple but critical: before every descent, verify the fuel selector position. Establish a habit of checking it during phase transitions (e.g., at the start of descent, before entering the pattern, before final approach). Know which tank is actually feeding the engine. If the engine loses power on approach and you suspect fuel starvation, the first action is to switch to BOTH or to the other tank — not to troubleshoot the engine. The C172N has two 26.5-gallon tanks (53 gallons usable total). Each tank feeds independently when selected; there is no crossfeed. Fuel starvation from a single-tank selection is a choice, not an accident.