Rough Climb Over Central Florida
Carburetor ice, marginal climb performance, and a low-altitude decision — the C150's narrow margin for error
The scenario
Departing Lakeland Linder International Airport (KLAL), Lakeland, FL — Runway 10, climbing out on a 090° heading. Elevation 142 ft MSL; the runway is essentially at sea level. KLAL is a towered Class D airport, open 24 hours.
It is a warm 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 9 SM. Humidity is high — the relative humidity is 87%. This is exactly the environment the FAA icing probability chart marks as 'serious icing at glide power, moderate icing at cruise power' for the C150's Continental O-200 carbureted engine.
You are 350 ft AGL, climbing through 68 KIAS (Vy, best rate of climb), heading 090°, when the engine begins to run rough. Power is noticeably down — the tachometer is dropping. The off-field environment to the east (Runway 10 climb-out) is marginal: low-density development, open developed areas (parks/large lots), and dense development. The airport is behind you. KLAL tower is active and aware of your departure.
Aircraft: Cessna 150M, solo, full fuel (18 gal usable), within limits. Continental O-200-A, 100 hp, fixed-pitch prop, carbureted, steam panel. Nothing was written up; the airplane was airworthy at departure. This is a marginal-climb airplane — especially at gross weight, in heat, and in high density altitude. You are at 142 ft field elevation with OAT 26°C; density altitude is roughly 1,800 ft.
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 the engine sounded normal at first.
- {'label': 'Field', 'value': 'KLAL · Lakeland Linder'}
- {'label': 'Runways', 'value': '5/23 · 10/28'}
- {'label': 'Elevation', 'value': '142 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 engine ran rough and lost power. The probable cause was carburetor ice formation, with the pilot's delayed use of carburetor heat as a contributing factor. The pilot had not applied carburetor heat proactively in conditions that clearly warranted it.
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 pilot applied carburetor heat but did so improperly (partial heat, not full on), which worsened the situation. 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 at all. The student 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. The probable cause was carburetor ice formation and the pilot's failure to apply carburetor heat when the power loss occurred.
NTSB ERA21LA284 (2021): A Cessna 150 instructional aircraft lost engine power during takeoff due to carburetor icing and made a forced landing into trees near Elba, Alabama. The accident resulted from carburetor ice formation under atmospheric conditions conducive to serious icing at glide power, with insufficient time to melt accumulated ice despite carburetor heat application. The probable cause was partial loss of engine power due to carburetor ice formation.
NTSB CEN23FA077 (2023, FATAL): A Cessna 150H on an instructional flight conducted a night visual approach to a non-towered airport 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 probable cause was the flight instructor's failure to maintain control after a loss of engine power due to carburetor icing while maneuvering for forced landing in dark night visual meteorological conditions.
The real accidents cited above occurred at other airports and in other regions — NOT at Lakeland Linder International Airport. KLAL has its own accident history (dominant patterns: loss of control inflight 23.7%, loss of control ground 19.4%, forced landing 17.2%), but these specific carburetor ice events happened elsewhere. The scenario is localized to KLAL 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 or improper application.
Key lesson — In warm, humid Florida air, the C150's carbureted Continental O-200 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 marginal off-field terrain, the decision window is measured in seconds — not minutes. Off Runway 10 at KLAL, the off-field environment is marginal: low-density development, parks, and dense development. A delayed response means a forced landing in terrain that may be survivable but is not ideal.
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 Florida afternoon conditions at KLAL. 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 is carbureted; it has no alternate air system or fuel injection. Carburetor heat is the only tool. At KLAL, with OAT 26°C and dew point 21°C, you are in the serious icing range at glide power.
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. In the C150, marginal climb performance means you cannot afford to lose RPM.
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 (as in NTSB ANC25LA005) can worsen the situation by partially melting ice into water ingestion without fully clearing the restriction.
At KLAL Runway 10, an engine failure on departure is a forced landing in marginal terrain.
The off-field environment off Runway 10's departure end (heading 090°) is marginal: low-density development, open developed areas (parks/large lots), and dense development. There is no ideal landing surface. If the engine quits on the Runway 10 departure and altitude is insufficient to return to the airport, the outcome is a forced landing in terrain that may be survivable but is not ideal. This is not a worst-case scenario; it is the geographic reality. Best glide is 60 KIAS. Doors unlatched before landing. 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 10.
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 Florida 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 over marginal terrain is waiting too long. The C150 is a marginal-climb airplane; you cannot afford to lose power.
Built from the real accident record
Scenario built from NTSB ERA25LA028 (2024 C150H carburetor ice / delayed carb heat), ANC25LA005 (2024 C150 partial power loss / improper carb heat use), ERA24LA087 (2024 C150M student failure to apply carb heat), WPR21LA329 (2021 C150D engine surge / delayed carb heat), CEN21LA381 (2021 C150M takeoff carb ice / forced landing), ERA21LA284 (2021 C150 takeoff carb ice / impact with trees), and CEN23FA077 (2023 fatal C150H night approach / carb ice / loss of control). Localized to KLAL.
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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