Rough Climb Over Sarasota Bay
Carburetor ice, partial power loss, and a marginal off-field environment — the decision clock is measured in seconds
The scenario
Departing Sarasota Bradenton International Airport (KSRQ), Runway 04, climbing out on a 038° heading. Elevation 30 ft MSL; the runway is essentially at sea level. You are solo, full fuel, within limits.
It is a hazy 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 7 SM. Relative humidity is near 80% — exactly the environment the FAA icing probability chart marks as 'serious icing at glide power, moderate icing at cruise power.' The Continental O-200-A in this C150M is carbureted; it has no fuel injection, no boost pump, no alternate air system. Carburetor heat is the only tool.
You are 350 ft AGL, climbing through 68 KIAS (Vy, best rate of climb), heading 038°, when the engine begins to run rough. Power is noticeably down — the tachometer is dropping. The off-field environment ahead (off Runway 04's climb-out end) is marginal: medium development, wooded wetland, low-density development. Behind you is the airport. Sarasota Bay is to your left.
Aircraft: Cessna 150M, solo, full fuel, within limits. Continental O-200-A, fixed-pitch prop, steam panel, fuel selector on BOTH. Nothing was written up; the airplane was airworthy at departure. The tower is open (it is 0800 local; tower operates 0600–0000). You are in Class C airspace (ceiling 4,000 MSL).
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': 'KSRQ · Sarasota Bradenton'}
- {'label': 'Runways', 'value': '4/22 · 14/32'}
- {'label': 'Elevation', 'value': '30 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 carburetor ice in the C150M? (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. The pilot had not applied carburetor heat proactively despite conditions that clearly warranted it.
NTSB ANC25LA005 (2024): A Cessna 150 on a personal flight experienced partial engine power loss due to carburetor ice formation during initial climb in conditions with 70% relative humidity conducive to serious icing at glide power. The accident resulted from the pilot's improper use of carburetor heat — the pilot applied it but did not leave it on, allowing ice to reform.
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 forced landing and a runway excursion — the student pilot failed to attain a proper touchdown point during the diversionary landing.
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 ERA21LA284 (2021): A Cessna 150 instructional aircraft lost engine power during takeoff due to carburetor icing and made a forced landing into trees. The accident resulted from carburetor ice formation under atmospheric conditions conducive to serious icing at glide power, with contributing factors including insufficient time to melt accumulated ice despite carburetor heat application.
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 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 Sarasota Bradenton International Airport. KSRQ has its own accident history (dominant patterns: loss of control ground 19.2%, forced landing 15.4%, runway excursion 11.5%), but these specific carburetor ice events happened elsewhere. The scenario is localized to KSRQ 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 C150M 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 (partial heat, or cycling it on and off).
Key lesson — In warm, moist Florida 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 marginal terrain, the decision window is measured in seconds — not minutes. Off Runway 04 at KSRQ, the off-field environment is marginal: medium development, wooded wetland, low-density development — survivable with proper technique, but not ideal. A delayed response means a forced landing in difficult terrain, not a comfortable return 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 Florida morning conditions at KSRQ. 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 fuel injection, no boost pump, 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. At 350 ft AGL on departure, you have seconds to respond.
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 KSRQ Runway 04, an engine failure on departure is a forced landing in marginal terrain.
The off-field environment off Runway 04's departure end (heading 038°) is marginal: medium development, wooded wetland, low-density development. There is no ideal alternate landing surface. If the engine quits on the Runway 04 departure and altitude is insufficient to return to the airport, the outcome is a forced landing in difficult terrain. 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 04.
Proactive carb heat use in conducive conditions is not optional.
The C150M 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.
Built from the real accident record
Scenario built from NTSB ERA25LA028 (2024 C150H carburetor ice / delayed carb heat), ANC25LA005 (2024 C150 carb ice on Mogas), ERA24LA087 (2024 C150M student failure to apply carb heat), WPR21LA329 (2021 C150D engine surge / carb ice), CEN21LA381 (2021 C150M carb ice on takeoff), ERA21LA284 (2021 C150 carb ice / forced landing into trees), and CEN23FA077 (2023 fatal C150H carb ice / night approach). Anonymized and localized to KSRQ.
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.
Open the interactive scenario →All sample scenarios · More Cessna 150M scenarios · More scenarios at KSRQ