Fuel Tank Confusion on Descent
Fuel starvation from improper tank selection in a high-performance single — the constant-speed prop and glass panel mask the problem until it is too late
The scenario
Departing Zephyrhills Municipal Airport (KZPH), Zephyrhills, FL — Runway 19, climbing out on a 180° heading. Field elevation 90 ft MSL. It is a clear, calm afternoon in central Florida: OAT 24°C, winds calm to light, visibility 10+ SM. A routine VFR flight — you departed 1.5 hours ago on a cross-country to a nearby field and are now returning home.
You are at 2,500 ft MSL, 15 nm south of KZPH, on a direct descent to the field. The Cirrus SR22's Perspective glass panel is showing all green. The constant-speed prop is in cruise configuration. You are planning to enter a standard left downwind for Runway 19 and land.
Fuel status: you departed with both tanks full (47 gallons usable total — 23.5 gal per tank). You have been flying for 1.5 hours at a cruise power setting of 65% (roughly 12–13 gal/hr burn). You estimate you have roughly 18–20 gallons remaining — plenty of fuel for the descent, approach, and landing, plus a comfortable reserve.
Fuel selector: currently on RIGHT tank. You have not switched tanks during the flight — you departed on the right tank and have been running it the entire 1.5 hours. The left tank has not been used.
Aircraft: Cirrus SR22, solo, within limits. The fuel selector has only two positions: LEFT and RIGHT — there is no BOTH. The Perspective panel shows fuel quantity digitally, but you have not cross-checked the gauges with a visual inspection of the tanks since preflight.
Pilot: you — a Private pilot, roughly 300 hours total, with 50 hours in the SR22. You are current and comfortable with the airplane. You did not visually verify fuel quantity in each tank during preflight — you relied on the Perspective fuel quantity display, which showed 47 gallons at startup. You have not thought much about fuel management during the flight; the panel shows plenty of fuel remaining.
- {'label': 'Field', 'value': 'KZPH · Zephyrhills'}
- {'label': 'Runways', 'value': '19/1 · 5/23'}
- {'label': 'Elevation', 'value': '90 ft'}
- {'label': 'Aircraft', 'value': 'SR22'}
- {'label': 'Dominant phase', 'value': 'Landing / Cruise'}
The decision
Before we get into the decision tree — what do you already know about fuel management in the SR22? (Pick all that apply; this records your baseline.)
What the record shows
What the NTSB files show
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. The pilot had failed to monitor fuel tank status and did not switch tanks proactively.
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.
NTSB DFW05CA087 (2005): A Cessna TU206G amphibian on a personal flight from Addison to Lancaster lost engine power during approach when the pilot switched fuel tanks. The accident resulted from fuel starvation attributed to the pilot's failure to visually verify fuel quantity before departure and inadequate fuel management during the approach.
NTSB ERA17LA205 (2017): A Cessna P206 on a post-maintenance break-in flight lost all engine power due to fuel starvation when the pilot mismanaged fuel selection and ran the right tank dry. The pilot made a forced landing in trees short of the runway after the engine quit during approach.
The common thread across all these accidents: fuel starvation from improper tank selection and failure to monitor fuel tank status. In the SR22, the fuel selector has only LEFT and RIGHT positions — there is no BOTH. Running one tank to exhaustion without switching means fuel starvation even if the other tank has usable fuel. Visual verification of fuel quantity in each tank during preflight, a proactive fuel tank switching plan, and switching tanks well before the active tank runs dry are the keys to avoiding this accident.
The real accidents cited above occurred in other aircraft at other airports — NOT at KZPH. The scenario is localized to KZPH to make the off-field environment real and consequential for you as a student here. Off Runway 19's approach end, the environment is mixed open developed (parks/large lots), evergreen forest, and low-density development — not open water, but not ideal for a forced landing either.
Key lesson — In the SR22, fuel tank management is not optional. The fuel selector has LEFT and RIGHT positions only — no BOTH. Visually verify fuel quantity in each tank during preflight; do not rely on the Perspective fuel quantity display alone. Establish a fuel tank switching plan before flight and execute it proactively — switch tanks well before the active tank runs to exhaustion. Running one tank dry while the other has fuel is a fatal mistake. At low altitude on approach, fuel starvation leaves you with only two options: best glide to the runway (if altitude permits) or CAPS deployment.
Debrief — teaching points
The SR22 fuel selector is LEFT / RIGHT only — there is no BOTH position.
Unlike some aircraft (e.g., Cessna 172 with BOTH), the SR22 requires active fuel tank management. You must consciously select which tank is feeding the engine. If you run one tank to exhaustion without switching, you will experience fuel starvation — the engine will lose power — even if the other tank has usable fuel. This is not a system failure; it is a design feature that requires pilot discipline.
Visual verification of fuel quantity is essential during preflight.
The Perspective fuel quantity display can be inaccurate if the tanks are not properly sumped, if there is contamination, or if the capacitance probes are fouled. Always visually inspect the fuel sight gauges on the fuselage during preflight. Look at each tank and confirm the fuel level matches the Perspective display. If there is a discrepancy, investigate before flight. Do not rely on the glass panel alone.
Establish a fuel tank switching plan before flight and execute it proactively.
A typical plan for a 2-hour flight might be: depart on the right tank for 1 hour, switch to the left tank for the next hour, then switch back to the right tank for the approach and landing. This balances fuel consumption and ensures you do not run one tank to exhaustion. Write the plan down. Brief it to yourself before departure. Execute it — do not skip it or delay it because the engine is running fine. Fuel starvation happens to pilots who think 'the engine is running, so I don't need to switch tanks yet.'
Monitor fuel tank status continuously during flight.
Glance at the Perspective fuel quantity display every few minutes. Note which tank is selected. If you are on the right tank and it is showing a lower quantity than expected, switch to the left tank sooner rather than later. Do not wait until the active tank is nearly empty. The margin for error is small, especially on approach.
Best glide speed (88 KIAS) is the immediate response to engine failure.
If the engine fails, lower the nose to 88 KIAS best glide speed immediately. This maximizes glide distance and gives you the best chance of reaching a landing surface. Do not try to stretch the glide by flying slower — that will only reduce glide distance and increase the risk of a stall. At low altitude on approach, best glide may allow you to reach the runway; at higher altitude, it gives you time to diagnose the problem or prepare for a forced landing.
CAPS deployment is the correct response to engine failure without a safe landing option.
The SR22's CAPS whole-airframe parachute is the POH's primary response to engine failure at low altitude without a safe landing option. It is not a recovery maneuver — it is a survival system. If you are at 500 ft AGL with no engine and the runway is not reachable, deploy CAPS. The parachute will slow your descent to roughly 17 ft/sec and allow a controlled landing in the off-field environment. A hard landing under CAPS is survivable; an uncontrolled descent or stall/spin is not.
Built from the real accident record
Scenario inspired by NTSB WPR24LA167 (2024 Harvard fuel starvation / tank selection), GAA19CA534 (2019 PA-28 fuel starvation on descent), DFW05CA087 (2005 Cessna TU206 fuel starvation / approach), and ERA17LA205 (2017 Cessna P206 fuel starvation / forced landing). Real events occurred at other airports and aircraft — localized to KZPH SR22 operations.
NTSB reports: WPR24LA167 · GAA19CA534 · DFW05CA087 · ERA17LA205
ACS tasks: PA.I.F — Weather Information · PA.I.G — Cross-Country Flight Planning · PA.II.A — Preflight Assessment · PA.II.B — Engine Starting / Systems Preflight · PA.IX.C — Emergency Approach and Landing · PA.I.H — Human Factors
Relevant FARs: §91.3 · §91.13 · §91.185
Step through the full decision tree, make the calls, and see where each choice leads — then debrief it with your CFI.
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