Rough Air Over Tampa North
Carburetor ice, marginal climb, and poor off-field options — a C150M at its limits
The scenario
Departing Tampa North Aero Park Airport (X39), Tampa, FL — Runway 14, climbing out on a 141° heading. Elevation 68 ft MSL. Non-towered field, Class G airspace, but you are climbing toward the overlying Tampa Class B (ceiling 3,000 MSL). CTAF is 122.8.
It is a warm, humid Florida morning in late spring: OAT 26°C, dew point 21°C, altimeter 29.94. Scattered clouds at 2,200 ft, light rain shower one mile to the northeast. Visibility 7 SM. The humidity is high — 85% relative humidity — and the temperature/dew point spread is narrow. This is exactly the environment the FAA icing probability chart marks as 'serious icing at glide power, moderate icing at cruise power.' You did not apply carburetor heat during the run-up because the engine ran smoothly.
You are 350 ft AGL, climbing through 68 KIAS (Vy, best rate of climb), heading 141°, when the engine begins to run rough. Power is noticeably down — the tachometer is dropping. The off-field environment off Runway 14's climb-out is poor: medium development, low-density development, and wooded wetland. No clear field, no road, no park. The C150M is marginal on climb at gross weight in these conditions — you are at best glide speed already, and the engine is getting worse.
Aircraft: Cessna 150M, solo, full fuel (24 gal), within limits. Continental O-200-A, 100 hp, carbureted, 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 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 heads-down on the climb and the engine sounded normal until just now.
- {'label': 'Field', 'value': 'X39 · Tampa North Aero Park'}
- {'label': 'Runways', 'value': '14/32'}
- {'label': 'Elevation', 'value': '68 ft'}
- {'label': 'Aircraft', 'value': 'C150'}
- {'label': 'Dominant phase', 'value': 'Takeoff / Landing'}
The decision
Before we get into the decision tree — what do you already know about the C150M's climb performance and carburetor ice? (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 temperature/dew point spread conducive to serious icing. 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.
NTSB ANC25LA005 (2024): A Cessna 150 on a personal flight experienced partial engine power loss due to carburetor ice during initial climb in conditions with 70% relative humidity conducive to serious icing at glide power. The probable cause was improper use of carburetor heat while operating on Mogas in icing conditions.
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 accident resulted in a runway excursion during the diversionary landing.
NTSB CEN21LA381 (2021): A Cessna 150 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 CEN23FA401 (2023, FATAL): A Cessna 150K on an instructional flight experienced partial engine power loss due to fuel system blockage and subsequently stalled during a descending left turn at low altitude. The accident resulted from fuel starvation and the flight instructor's failure to maintain adequate airspeed after the power loss.
NTSB CEN23FA077 (2023, FATAL): A Cessna 150H on an instructional flight conducted a night visual approach in dark conditions with no cultural lighting. The aircraft descended below safe altitude and impacted a farm field 1.2 miles short of the runway. The accident was attributed to loss of engine power due to carburetor icing and the flight instructor's failure to apply carburetor heat.
The real accidents cited above occurred at other airports and in other aircraft — NOT at Tampa North Aero Park Airport (X39). X39 has its own accident history dominated by loss-of-control events (27.3% of accidents), loss-of-control-ground events (18.2%), and hard landings (9.1%). The scenario is localized to X39 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, 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 C150M'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 over poor off-field terrain, the decision window is measured in seconds — not minutes. Off Runway 14 at X39, the off-field environment is medium development, low-density development, and wooded wetland: a delayed response means a forced landing in poor terrain, not a field landing.
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 X39. You do not need visible ice, freezing temperatures, or IMC. Warm, moist air at reduced power is the classic carb-ice environment. The C150M'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 C150M, 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 can worsen the situation by partially melting ice into water ingestion without fully clearing the restriction.
At X39 Runway 14, an engine failure on departure is a forced landing in poor terrain.
The off-field environment off Runway 14's departure end (heading 141°) is medium development, low-density development, and wooded wetland. There is no clear field, no road, no park. If the engine quits on the Runway 14 departure and altitude is insufficient to return to the airport, the outcome is a forced landing in poor terrain. This is not a worst-case scenario; it is the geographic reality. Best glide is 60 KIAS. 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 14.
The C150M is marginal on climb at gross weight — especially in heat or high density altitude.
With 100 hp and a light wing loading, the C150M is sensitive to weight, temperature, and density altitude. At gross weight (1,600 lb), on a warm day, at sea level, the best rate of climb (Vy) is 68 KIAS and the climb rate is marginal. Any power loss — even partial — can turn a climb into a descent. Understand your airplane's limits before you depart. If the engine is rough and power is down at 350 ft AGL, you are already in a precarious position.
Built from the real accident record
Scenario built from NTSB ERA25LA028, ANC25LA005, ERA24LA087, WPR21LA329, CEN21LA381, ERA21LA284, CEN23FA401, and CEN23FA077 — all Cessna 150-series carburetor ice and partial power loss events. Localized to Tampa North Aero Park Airport (X39).
NTSB reports: ERA25LA028 · ANC25LA005 · ERA24LA087 · WPR21LA329 · CEN21LA381 · ERA21LA284 · CEN23FA401 · 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.
Open the interactive scenario →All sample scenarios · More Cessna 150M scenarios · More scenarios at X39