Rough Climb Over Tampa Bay
Carburetor ice, partial power loss, and a low-altitude decision — the C172M's marginal climb performance makes this unforgiving
The scenario
Departing Tampa Executive Airport (KVDF), Tampa, FL — Runway 05, climbing out on a 042° heading into the morning haze. Elevation 22 ft MSL. It is a warm, humid Florida morning in late spring: OAT 24°C, dew point 19°C, altimeter 29.94. Scattered clouds at 2,500 ft, light rain showers two miles to the northeast. Visibility 7 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 350 ft AGL, climbing through 78 KIAS (Vy, best rate of climb), heading 042°, when the engine begins to run rough. Power is noticeably down — the tachometer is unwinding. The off-field environment ahead is mostly wooded wetland, pasture, and medium development — workable terrain for a forced landing, but you are still low. KVDF is non-towered (CTAF); you are in Class G airspace, but you are climbing toward the overlying Tampa Class B (floor 3,000 MSL). The airport is behind you.
Aircraft: Cessna 172M, solo, full fuel, within limits. Carbureted Lycoming O-320-E2D, 150 hp, fixed-pitch prop, steam panel (vacuum-driven attitude and heading), fuel selector on BOTH. Nothing was written up; the airplane was airworthy at departure. The 172M is the lower-powered variant of the 172 family — marginal climb performance is the defining trait, especially at gross weight or in heat.
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 haze ahead.
- {'label': 'Field', 'value': 'KVDF · Tampa Executive'}
- {'label': 'Runways', 'value': '5/23 · 18/36'}
- {'label': 'Elevation', 'value': '22 ft'}
- {'label': 'Aircraft', 'value': 'C172M'}
- {'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 C172M? (Pick all that apply; this records your baseline.)
What the record shows
What the NTSB files show
NTSB ERA09LA379 (2009): A Cessna 172M student pilot on a solo instructional flight experienced engine power loss during the base-to-final turn in the traffic pattern. The ambient conditions (75°F OAT, 55°F dew point) were conducive to serious carburetor icing per the FAA icing probability chart. The pilot made a forced landing in a field. The probable cause was partial loss of engine power for undetermined reasons — but the conditions and symptom pattern are consistent with carburetor icing at glide power.
NTSB DFW05CA237 (2005): A Cessna 172M lost engine power during initial climb due to carburetor icing and made a forced landing in a field. The pilot stalled while maneuvering to avoid a fence. Contributing factors included high density altitude, which compounded the C172M's already marginal climb performance. The probable cause was the pilot's failure to maintain airspeed — but the root cause was the loss of engine power due to carb icing.
NTSB CEN24LA168 (2024): A Cessna 172M on an IFR flight experienced engine power loss due to carburetor icing during descent in night IMC. The pilot touched down on a building roof and impacted a retaining wall and ground. The probable cause was the pilot's delayed use of carburetor heat, which resulted in ice accumulation beyond the point where heat could restore full engine power. By the time carb heat was applied, the ice was too heavy to clear.
NTSB CEN22LA181 (2022): A Cessna 172M on a personal flight experienced partial engine power loss during a go-around attempt from a low approach to an upsloping turf runway. The probable cause was the pilot's failure to use carburetor heat during the approach and an unsuitable flight profile for the runway configuration. The C172M's marginal climb performance meant that a partial power loss on a go-around was unrecoverable.
All of these real accidents occurred at other airports and in other circumstances — NOT at Tampa Executive Airport (KVDF). KVDF has its own accident history (see field dominant patterns: LOSS_OF_CONTROL_GROUND 18.4%, HARD_LANDING 18.4%, FORCED_LANDING 15.8%), but these specific NTSB 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 C172M is insidious and dangerous. The C172M's 150 hp engine has marginal climb performance — a partial power loss on climb-out is more critical in this airplane than in the higher-powered 172N. 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 C172M'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 on climb-out, the decision window is measured in seconds — not minutes. The C172M's marginal climb performance means a partial power loss on departure is unforgiving. Off Runway 05 at KVDF, the off-field environment is wooded wetland and pasture — workable for a forced landing. Off Runway 36, it is open water — a ditching. Know your escape route before you line up.
Debrief — teaching points
Carburetor ice forms in conditions you would not expect — and the C172M is particularly vulnerable.
The FAA icing probability chart shows 'serious icing at glide power' at temperatures between roughly 15°C and 25°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 C172M's Lycoming O-320 is carbureted; it has no alternate air system. Carburetor heat is the only tool. The 150 hp engine's marginal climb performance means that a partial power loss on climb-out is more dangerous in this airplane than in a 172N.
The first symptom is subtle — a dropping tachometer and engine roughness.
In a fixed-pitch airplane like the C172M, 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 C172M, with its marginal climb performance, early recognition is survival.
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 KVDF, know your off-field environment for each runway end.
Off Runway 05 (climb-out heading 042°): wooded wetland, pasture, medium development — workable for a forced landing. Off Runway 23 (climb-out heading 222°): pasture, open water, medium development — mixed. Off Runway 18 (climb-out heading 180°): low-density development, wooded wetland, open developed (parks/large lots) — marginal. Off Runway 36 (climb-out heading 360°): medium development, wooded wetland, open water — ditching. If the engine fails on climb-out and altitude is insufficient to return to the airport, you need to know where the best forced-landing terrain is. Runway 05 and 23 departures have workable off-field options. Runway 36 does not.
The C172M's marginal climb performance makes a partial power loss on departure unforgiving.
The C172M (150 hp) has a best rate of climb (Vy) of 78 KIAS and a best angle of climb (Vx) of 64 KIAS. At gross weight, in high density altitude, or with a full cabin, climb performance is marginal. A partial power loss on climb-out at 350 ft AGL means you are running out of altitude fast. Early recognition and immediate full carb heat is not optional — it is survival. If carb heat does not restore power within 15–20 seconds, establish 65 KIAS best glide and prepare for a forced landing.
Proactive carb heat use in conducive conditions is not optional.
The C172M 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 morning departure, with OAT near 24°C and dew point near 19°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 on climb-out is waiting too long. In the C172M, with its marginal climb performance, proactive carb heat is the professional standard.
Built from the real accident record
Scenario built from NTSB ERA09LA379 (2009 C172M carburetor ice / forced landing), DFW05CA237 (2005 C172M carb ice / stall on descent), CEN24LA168 (2024 C172M delayed carb heat / power loss), and CEN22LA181 (2022 C172M carb ice / go-around failure). Anonymized and localized to KVDF (Tampa Executive Airport).
NTSB reports: ERA09LA379 · DFW05CA237 · CEN24LA168 · CEN22LA181
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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