Every pilot knows they should read the operating handbook for their aircraft, but let’s face it—many don’t dive in as deeply as they should. In this article, we uncover 8 surprising facts tucked away in your Cessna POH. While this is tailored to the Cessna 150M, many of these insights apply to other Cessna models as well. Let’s see how well you know your airplane!
Disclaimer: Always consult your aircraft’s POH for specific procedures, limitations, and guidance.
1. Crosswind Landings and Flaps
Instructors often pass down techniques they learned during their training, even if they’re not entirely accurate. For example, you might have been taught to use partial flaps during crosswind landings. However, did you know that Cessna actually recommends as little as 0° of flaps when landing in strong crosswinds? For the Cessna 150M, the POH specifically states:
When landing in a strong crosswind, use the minimum flap setting required for the field length.
Be cautious, though—landing with less flap means a shallower approach and a longer landing distance. However, increased airflow over the control surfaces, especially the rudder, enhances their effectiveness. The rudder plays a critical role in crosswind landings, ensuring you maintain directional control. Landing too slowly risks a gust of wind overcoming ground steering before the full weight is on the wheels, while the rudder remains ineffective. The higher landing speed ensures the control surfaces stay effective, allowing for a smooth transition to nose wheel steering and differential braking.
2. Mixture Leaning in Cruise
Many pilots either forget to lean the mixture or were never taught how to do it properly. While we won’t dive into leaning techniques here, it’s important to know that Cessna’s performance calculations for cruise flight are based on a properly leaned mixture. This is crucial because flying with a full-rich mixture can burn up to 40% more fuel, foul spark plugs, and produce less power compared to a properly leaned, rich-of-peak setting.
For example, if you’re expecting to burn 5.5 gallons per hour (GPH) in cruise, but you’re actually burning 7.7 GPH due to an unleaned mixture, you’re setting yourself up for trouble. The result? You could run out of fuel prematurely—fuel starvation is one of the leading causes of engine failures. Don’t let this preventable mistake catch you off guard!
3. Full Rich During Climbs
For the Cessna 150, the POH recommends a full-rich mixture during enroute climbs below 5,000 feet to prevent engine overheating, which can cause serious damage. Above 5,000 feet density altitude, leaning the mixture as needed is advisable and supported by the POH.
When conducting the following climbs, the mixture should be full rich below 5000 feet and may be leaned, if necessary, above 5000 feet for smoother engine operation.
Remember, this guidance applies specifically to enroute climbs—not to intermediate level-offs or cruising below 5,000 feet. For instance, when leveling off beneath a Class B shelf, leaning the mixture is how the POH advises the plane to be flown as mentioned in point #2.
4. Carburetor Heat Limitations
Many pilots were taught to check the carb heat every now and then and use it during landing. However, it is much more nuanced than that. Here are a few specific instructions and limitations straight from the POH regarding carb heat:
- Icing encounter: “Watch for signs of carburetor air filter ice and apply carburetor heat as required. An unexpected loss in engine speed could be caused by carburetor ice or air intake filter ice. Lean the mixture for maximum RPM, if carburetor heat is used continuously.”
- Emergency decent through clouds: “Use full carburetor heat”
- If carb icing is persistent in cruise: “use the minimum amount of heat necessary to prevent ice from forming and lean the mixture slightly for smoothest engine operation.”
- DO NOT USE CARB HEAT ON THE GROUND (Unless there is specifically carb ice). Remember that carb heat air is unfiltered.
“The carburetor heat control knob should be pushed full in during all ground operations unless heat is absolutely necessary. When the knob is pulled out to the heat position, air entering the engine is not filtered.” - Extremely cold (Less than -18°C): “Pull carburetor heat knob full on after engine has started. Leave on until engine is running smoothly.”
- Extremely cold limitation (Less than -18°C): “When operating in temperatures below -18°C, avoid using partial carburetor heat. Partial heat may increase the carburetor air temperature to the 0° to 21°C range, where icing is critical under certain atmospheric conditions.”
5. Increased Cruise Range via the Mixture
The Cessna 150M POH provides a simple tip to maximize cruise range:
For best fuel economy at 65% power or less, operate at the leanest mixture that results in smooth engine operation or at 50 RPM on the lean side of the peak RPM, whichever occurs first. This will result in approximately 5% greater range than shown in this handbook.
Following this method can increase your range by approximately 5% beyond what’s shown in the handbook. And remember the handbook already shows cruise data with a leaned mixture. While there are other leaning techniques, this straightforward approach is outlined directly in the POH, making it accessible to any pilot looking to improve fuel efficiency.
6. Increasing Throttle Sprays Fuel into the Carburetor
The Cessna 150M uses an “up-draft, float-type, fixed jet carburetor mounted on the bottom of the engine.” The “jet” means that increasing the throttle sprays fuel into the carburetor, allowing the engine to seamlessly increase power during flight. However, this design poses a fire hazard on the ground.
Pumping the throttle on the ground can cause excess fuel to accumulate and flow downhill into the carb box, outside the carburetor. This excess fuel can ignite in multiple ways. For this reason, the POH advises a brief engine run-up in the event of an engine fire on the ground. This process pulls the fire into the induction system and the engine, minimizing damage.
Avoid this risk entirely—don’t pump the throttle on the ground.
7. Single Cable Flaps
In many Cessnas, including the C-150M, the flaps are operated by a single motor and connected by one cable to both flaps. This design minimizes the likelihood of asymmetric flaps, as a broken cable would cause both flaps to retract to 0° due to airflow. However, this sudden retraction carries its own risks, such as a rapid change in lift and drag. For this reason, some pilots avoid using full flaps unless absolutely necessary, such as for landing on very short runways.
8. More Fuel Savings
According to the operating limitations, “normal cruising is performed between 55% and 75% power.” At 4,000 feet, for example, the cruise table shows a fuel burn of 5.8 GPH at 75% power, compared to just 4.1 GPH at 55% power—a significant savings. The tradeoff? A modest speed reduction of only 14 knots.
If you’re not in a rush, this is an excellent way to conserve fuel, especially during non-engine-intensive activities like ground reference maneuvers or logging flight hours. It’s a smart strategy for maximizing efficiency while flying!
Safely Operating your Cessna
The Pilot’s Operating Handbook (POH) is more than just a required document—it’s a treasure trove of knowledge that can make you a safer, more efficient pilot. From mastering crosswind landings to saving fuel and understanding critical systems, the POH provides invaluable insights that are often overlooked.
By taking the time to explore and apply these lesser-known facts, you not only enhance your skills but also ensure you’re operating your Cessna at its best. Remember, the POH is your ultimate guide to understanding the aircraft, so refer to it regularly and let it guide your decisions in the air.
Fly safe, and always keep learning!
