Engine Failure Over Tampa Bay
Partial power loss at low altitude, open water ahead, and a decision window measured in seconds — the off-field environment is not forgiving
The scenario
Departing Albert Whitted Airport (KSPG), St. Petersburg, FL — Runway 07, climbing out over Tampa Bay on a 062° heading. Elevation 7 ft MSL; the runway is essentially at sea level.
It is a hazy Florida afternoon in late spring: OAT 28°C, dew point 22°C, altimeter 29.92. Scattered clouds at 2,500 ft, light rain shower two miles to the northeast. Visibility 8 SM. Classic Gulf Coast conditions — warm, moist, and exactly the environment the FAA icing probability chart marks as 'serious icing at glide power, moderate icing at cruise power.'
You are 400 ft AGL, climbing through 73 KIAS (Vy), heading 062°, when the engine begins to run rough. Power is noticeably down — the tachometer is dropping. The water of Tampa Bay fills the windscreen ahead. KSPG's tower is part-time (0700–2100) and is open; you are in Class D airspace.
Aircraft: Cessna 172N, solo, full fuel, within limits. Carbureted Lycoming O-320, fixed-pitch prop, steam panel, fuel selector on BOTH. Nothing was written up; the airplane was airworthy at departure.
Pilot: you — a Private pilot, current, roughly 200 hours total. You did not apply carburetor heat during the run-up because the engine ran smoothly. You did not apply it after takeoff because you were heads-down on the climb.
- {'label': 'Field', 'value': 'KSPG · Albert Whitted'}
- {'label': 'Runways', 'value': '7/25 · 18/36'}
- {'label': 'Elevation', 'value': '7 ft'}
- {'label': 'Aircraft', 'value': 'C172N'}
- {'label': 'Dominant phase', 'value': 'Landing / Takeoff'}
The decision
Before we get into the decision tree — what do you already know about engine failure at low altitude over water in the C172N? (Pick all that apply; this records your baseline.)
What the record shows
What the NTSB files show
NTSB CEN24LA362 (2024): A Cessna 172N encountered light rain and carburetor ice at 1,800 ft AGL. The engine ran rough and lost power. The probable cause was carburetor ice formation in conditions conducive to serious icing, with insufficient time and altitude for carburetor heat to clear the accumulated ice. The pilot had not applied carburetor heat proactively in conditions that clearly warranted it.
NTSB CEN14LA276 (2014): A Cessna 172N on a cross-country flight experienced engine roughness and power loss at cruise altitude in conditions conducive to carb icing. The pilot made a forced landing on an island; the aircraft nosed over in soft sand. The pilot survived. The probable cause could not be determined due to premature aircraft release — but the conditions and symptoms are consistent with carburetor ice.
NTSB ANC26LA001 (2025): A Cessna 172 on an instructional flight experienced progressive engine power loss during training maneuvers despite carburetor heat application. The pilot made a forced landing on a road; the aircraft struck a rock during landing roll and nosed over. Atmospheric conditions indicated serious icing conditions in pressure-type carburetors — a reminder that even full carb heat may not immediately clear heavy ice accumulation.
NTSB WPR15LA086 (2015): A Cessna 172N over mountainous terrain experienced partial loss of engine power during a climb. The pilot made a forced landing into densely forested terrain. The reason for the partial loss of engine power could not be determined because the aircraft was not recovered from the remote accident site.
NTSB CEN14LA374 (2014): A Cessna 172N experienced partial engine power loss during cruise due to failure of the dual magneto system caused by loose mounting screws. Improper maintenance during the annual inspection was a contributing factor. The lesson: a thorough preflight and attention to engine instruments can catch degrading power before it becomes critical.
NTSB WPR14LA099B (2014): A Piper PA-24 (not a C172N, but the lesson applies) experienced partial engine power loss during initial climb due to water-contaminated fuel. The pilot failed to sump the fuel tanks during preflight. A forced landing resulted in a collision with a taxiing airplane. The lesson: fuel contamination is a preflight discovery, not an in-flight surprise.
NTSB WPR12LA306 (2012): A Cessna 172N experienced partial loss of engine power during cruise due to failure of the No. 3 cylinder exhaust valve. The pilot made a forced landing in a wheat field. The lesson: mechanical failures are less common than carburetor ice or fuel contamination, but they happen. Proper preflight and attention to engine instruments are the only defenses.
The local environment at KSPG makes this scenario particularly unforgiving: Runway 07's departure end is open water — Tampa Bay. An engine failure on the Runway 07 departure at low altitude is a ditching, not a field landing. There is no open field, no road, no park. The water is the off-field environment. This is not hypothetical; it is the NLCD ground cover off that runway end.
The real accidents cited above occurred at other airports and in other aircraft — NOT at Albert Whitted Airport. KSPG has its own accident history (dominant patterns: LOSS_OF_CONTROL_INFLIGHT 20.0%, FORCED_LANDING 16.4%, LOSS_OF_CONTROL_GROUND 14.5%, DITCHING 12.7%, STALL_SPIN 12.7%), but these specific events happened elsewhere. The scenario is localized to KSPG to make the off-field environment real and consequential for you as a student here.
The consistent thread across all these events: engine power loss in the C172N is insidious. It builds gradually, the first symptom is roughness and a dropping tachometer (not a dramatic power cut), and by the time it is obvious, it may be too late for a comfortable recovery. The fix — full carburetor heat, immediately, at the first sign of roughness in conducive conditions — is simple. The failure is always a delay.
Key lesson — In warm, moist Gulf Coast air, the C172N's carbureted O-320 can accumulate serious carburetor ice even at cruise power and above-freezing temperatures. Apply full carburetor heat at the first sign of engine roughness or unexplained RPM loss. At low altitude over water, the decision window is measured in seconds — not minutes. Off Runway 07 at KSPG, the off-field environment is Tampa Bay: a delayed response means a ditching, not a field landing. Know your best glide speed (65 KIAS), know the off-field environment off each runway end, and know when to declare an emergency and execute a controlled ditching rather than try to stretch a glide to the airport.
Debrief — teaching points
Carburetor ice forms in conditions you would not expect.
The FAA icing probability chart shows 'serious icing at glide power' at temperatures between roughly 20°C and 30°C when relative humidity is high — exactly the Gulf Coast afternoon conditions at KSPG. You do not need visible ice, freezing temperatures, or IMC. Warm, moist air at reduced power is the classic carb-ice environment. The C172N's Lycoming O-320 is carbureted; it has no alternate air system. Carburetor heat is the only tool. Proactive application of carb heat during the run-up check (and confirmation of the expected RPM drop and recovery) is the first line of defense.
The first symptom is subtle — a dropping tachometer and engine roughness.
In a fixed-pitch airplane like the C172N, carburetor ice first shows as engine roughness and an unexplained RPM decrease. There is no dramatic power cut. Pilots who are not actively monitoring the tachometer miss the early warning. By the time the roughness is obvious, significant ice has accumulated. Scan the tachometer as part of your regular instrument scan, especially in conducive conditions. At 400 ft AGL over water, a 30-second delay in recognizing and acting on a dropping tachometer can be the difference between a successful recovery and a ditching.
Apply full carburetor heat — not partial — and expect an initial RPM drop.
When you apply carb heat to an iced carburetor, the RPM will drop further before it rises. This is expected and normal: the heat is melting ice and the resulting water is briefly disrupting combustion. Do not remove carb heat when the RPM drops — that is the heat working. Hold it full on. The RPM will recover as the ice clears, typically within 15–30 seconds depending on ice accumulation. Partial carb heat can worsen the situation by partially melting ice into water ingestion without fully clearing the restriction.
At KSPG Runway 07, an engine failure on departure is a ditching.
The off-field environment off Runway 07's departure end (heading 062°) is open water — Tampa Bay. There is no alternate landing surface. If the engine quits on the Runway 07 departure and altitude is insufficient to return to the airport, the outcome is a ditching. This is not a worst-case scenario; it is the geographic reality. Best glide is 65 KIAS. Doors unlatched before water contact. Master off just before impact. Flaps for slowest possible touchdown speed — impact energy rises with the square of touchdown speed, so the slowest possible speed matters most. Know this before you line up on Runway 07. Consider Runway 25 (heading 242°) for departures when conditions are marginal — its climb-out environment is dense development, but at least it is over land.
Proactive carb heat use in conducive conditions is not optional.
The C172N POH and the FAA Pilot's Handbook of Aeronautical Knowledge both recommend applying carburetor heat when conditions are conducive to icing — before the symptom appears. In a Gulf Coast summer departure, with OAT near 28°C and dew point near 22°C, that means applying carb heat during the run-up check (and confirming the expected RPM drop, then recovery) and considering its use during climb in visible moisture or high humidity. Waiting for the roughness to appear at 400 ft AGL over Tampa Bay is waiting too long.
Know the off-field environment off each runway end at your home field.
KSPG has four runway ends, and each has a different off-field environment: Runway 07 (ditching — open water), Runway 25 (poor — dense development), Runway 18 (ditching — open water), Runway 36 (ditching — open water). If you have an engine failure at low altitude, your options are constrained by geography. A forced landing in dense development is survivable; a ditching in open water is survivable if controlled, but not if you are trying to stretch a glide to the runway. Know your best glide speed, know the off-field environment, and know when to declare an emergency and execute a controlled ditching rather than try to make the airport.
Declare an emergency early — do not wait for the engine to quit.
At 400 ft AGL over water with a rough engine, a precautionary emergency declaration is appropriate. It alerts ATC, it gives you priority, and it sets the tone for a controlled response. Do not wait for total power loss; declare when you recognize that the situation is beyond your ability to manage normally. 14 CFR §91.3 makes the PIC the final authority — use that authority to protect yourself and your airplane.
Built from the real accident record
Scenario built from NTSB CEN24LA362 (2024 C172N carburetor ice / power loss), CEN14LA276 (2014 C172N forced landing / power loss), ERA09LA517 (2009 C172N total power loss), ANC26LA001 (2025 C172N progressive power loss despite carb heat), WPR15LA086 (2015 C172N partial power loss / forced landing), CEN14LA374 (2014 C172N partial power loss / magneto failure), WPR14LA099B (2014 C172N water-contaminated fuel / forced landing), and WPR12LA306 (2012 C172N exhaust valve failure / forced landing). Localized to KSPG.
NTSB reports: CEN24LA362 · CEN14LA276 · ERA09LA517 · ANC26LA001 · WPR15LA086 · CEN14LA374 · WPR14LA099B · WPR12LA306
ACS tasks: PA.I.F — Weather Information · PA.I.G — Cross-Country Flight Planning · PA.IX.C — Emergency Approach and Landing · PA.I.H — Human Factors · PA.II.B — Engine Starting / Systems Preflight
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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