Rough Climb Over Tampa Bay
Carburetor ice, partial power loss, and a non-towered field with water off one runway — the decision window is tight
The scenario
Departing Tampa Executive Airport (KVDF), Tampa, FL — Runway 05, climbing out on a 042° heading. Elevation 22 ft MSL. Non-towered field; you are on CTAF 122.8. Class G airspace below 3,000 ft MSL; above 3,000 ft you enter the overlying Tampa Class B (3,000–10,000 MSL).
It is a warm, humid Florida morning in late spring: OAT 26°C, dew point 21°C, altimeter 29.94. Scattered clouds at 2,800 ft, light rain shower two miles to the northeast. Visibility 8 SM. This is classic Gulf Coast icing weather — the FAA icing probability chart marks this as 'serious icing at glide power, moderate icing at cruise power.' The temperature/dew point spread is tight; relative humidity is near 90%.
You are 350 ft AGL, climbing through 68 KIAS (Vy, best rate of climb), heading 042°, when the engine begins to run rough. Power is noticeably down — the tachometer is dropping. The off-field environment ahead (northeast of the runway) is wooded wetland, pasture, and medium development — not ideal, but landable. Behind you and to the south is open water and development. KVDF is non-towered; you are operating on CTAF and have no ATC oversight.
Aircraft: Cessna 150M, solo, full fuel (26 gal usable), within limits. Continental O-200-A, 100 hp, carbureted, fixed-pitch prop, steam panel. Nothing was written up; the airplane was airworthy at departure. Fuel selector is on BOTH.
Pilot: you — a Private pilot, current, roughly 180 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 focused on the climb and did not anticipate icing in these warm temperatures.
- {'label': 'Field', 'value': 'KVDF · Tampa Executive'}
- {'label': 'Runways', 'value': '5/23 · 18/36'}
- {'label': 'Elevation', 'value': '22 ft'}
- {'label': 'Aircraft', 'value': 'C150'}
- {'label': 'Dominant phase', 'value': 'Landing / Takeoff'}
The decision
Before we get into the decision tree — what do you already know about carburetor ice in the C150? (Pick all that apply; this records your baseline.)
What the record shows
What the NTSB files show
NTSB ERA25LA028 (2024): A Cessna 150H encountered carburetor ice at cruise altitude in conditions with 100% relative humidity and a temperature/dew point spread conducive to serious icing. The probable cause was the pilot's delayed use of carburetor heat while operating in icing conditions. The pilot did not apply carb heat until after significant power loss had occurred.
NTSB ANC25LA005 (2024): A Cessna 150 on initial climb experienced partial loss of engine power due to carburetor ice in conditions with 70% relative humidity conducive to serious icing at glide power. The probable cause was the pilot's improper use of carburetor heat while operating on Mogas in icing conditions — the pilot applied carb heat but did not hold it on continuously.
NTSB ERA24LA087 (2024): A Cessna 150M on a solo cross-country instructional flight experienced partial engine power loss due to carburetor icing when the student pilot failed to apply carburetor heat. The pilot made a diversionary landing but failed to attain a proper touchdown point, resulting in a runway excursion. The probable cause was the pilot's failure to use carburetor heat in icing conditions.
NTSB CEN21LA381 (2021): A Cessna 150M experienced partial engine power loss due to carburetor icing during takeoff near Wadsworth, Ohio, when the pilot failed to apply carburetor heat despite conditions in the moderate-to-serious icing range. The pilot made a forced landing to a corn field where the aircraft nosed over.
NTSB CEN23FA077 (2023, FATAL): A Cessna 150H on an instructional flight conducted a night visual approach to a non-towered airport in dark conditions. The aircraft descended below safe altitude and impacted a farm field 1.2 miles short of the runway. The probable cause was the flight instructor's failure to apply carburetor heat, resulting in a loss of engine power due to carburetor icing, and the failure to maintain control while maneuvering for a forced landing in dark night VFR conditions.
The real accidents cited above occurred at other airports and in other aircraft — NOT at Tampa Executive Airport (KVDF). KVDF has its own accident history (dominant patterns: loss of control on the ground, hard landings, forced landings, loss of control in flight, runway excursions), but these specific carburetor ice events happened elsewhere. The scenario is localized to KVDF to make the off-field environment real and consequential for you as a student here.
The consistent thread across all these events: carburetor ice in the C150 is insidious. It builds gradually in warm, moist air at reduced power. 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 or improper use (cycling it on and off, or applying it partially).
Key lesson — In warm, moist Gulf Coast air, the C150's carbureted Continental O-200-A 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, the decision window is measured in seconds — not minutes. Off Runway 05 at KVDF, the off-field environment is wooded wetland and pasture (landable); off Runway 36, it is open water (a ditching). Know your runway and the terrain before you line up.
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 morning conditions at KVDF. You do not need visible ice, freezing temperatures, or IMC. Warm, moist air at reduced power is the classic carb-ice environment. The C150's Continental O-200-A is carbureted; it has no alternate air system. Carburetor heat is the only tool.
The first symptom is subtle — a dropping tachometer and engine roughness.
In a fixed-pitch airplane like the C150, 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.
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 or cycling it on and off can worsen the situation by partially melting ice into water ingestion without fully clearing the restriction.
At KVDF, know your runway and the off-field environment.
Off Runway 05's departure end (heading 042°), the off-field environment is wooded wetland, pasture, and medium development — landable terrain. Off Runway 23's departure end (heading 222°), it is pasture, open water, and medium development — mixed. Off Runway 18's departure end (heading 180°), it is low-density development and wooded wetland — marginal. Off Runway 36's departure end (heading 360°), it is medium development, wooded wetland, and open water — a ditching risk. If the engine quits on the Runway 36 departure and altitude is insufficient to return to the airport, the outcome is a ditching in open water. Know this before you line up.
Proactive carb heat use in conducive conditions is not optional.
The C150 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 26°C and dew point near 21°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 350 ft AGL is waiting too long.
Built from the real accident record
Scenario built from NTSB ERA25LA028, ANC25LA005, ERA24LA087, WPR21LA329, CEN21LA381, ERA21LA284, and CEN23FA077 — all C150 carburetor ice events. Real accidents occurred at other airports; this scenario is localized to Tampa Executive Airport (KVDF).
NTSB reports: ERA25LA028 · ANC25LA005 · ERA24LA087 · WPR21LA329 · CEN21LA381 · ERA21LA284 · CEN23FA077
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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