How to Use the Mixture Control on an Airplane

Identify the mixture control. The control is generally either a lever or a push rod. Traditionally, the handle of the control is colored red or orange. However, it should also be labeled with words.

Learn the settings. As a rule of thumb, pushing the lever forward, or in, makes the mixture rich. Pulling it backward, or out, makes the fuel mixture lean. Rich means that a lot of air will be mixed with the fuel. Lean means that less air will be mixed with the fuel. When the engine is not running, the mixture control is normally set to "lean." This reduces the likelihood that the engine will start.

Set the mixture to "rich" prior to starting the engine. This is the normal procedure if the airport is at a low altitude above sea level. If the airport is at a higher altitude, over 3,000 feet, then it may be advisable to lean the mixture slightly before starting.

Lean the mixture gradually during flight, as you climb to higher altitudes. Generally, pilots begin leaning the mixture at approximately 4,000 feet msl. The higher you climb the more it is necessary to lean the mixture.

Locate the appropriate mixture setting for your given altitude. Do this by very gradually adjusting the mixture control while watching the tachometer. While you do this the throttle should not be adjusted, and the propeller control should be set for max RPM. As you pull the mixture back, you will see the RPM begin to rise a little. Continue slowly pulling the control back until the RPM begins to drop. Then begin slowly pushing the mixture control forward toward the rich setting once more. Locate the point at which the RPM is the highest. This is the optimum mixture setting.

Use the mixture control to shut down the engine after parking at your destination. This is normal practice in most aircraft of this type. Simply pull the mixture control all the way back to the fully lean position and the engine will shut down by itself. Then turn off the key and master switches.