In short: Energy management means understanding that an airplane can trade airspeed (kinetic energy) for altitude (potential energy) and back again, with engine power adding or removing energy. Rod Machado explains it with a bicycle coasting over a hill and warns that the dangerous state is low and slow, where only power can help.
Video: “Energy Management” by Rod Machado, from his YouTube channel.
What you’ll learn
- The difference between kinetic energy and potential energy, explained with a bicycle
- How airspeed and altitude can be converted into each other in flight
- Practical examples of trading energy on final approach
- How engine power changes the airplane’s total energy state
- Why low airspeed combined with low altitude is the energy state to avoid
- How a stabilized approach supports good energy management
What a bicycle teaches about energy
Rod notes that the FAA tends to make energy management sound more complicated than it is, so he uses an image nearly everyone knows. A cyclist pedals along a flat road at a steady 5 mph, then stops pedaling at the bottom of a hill. The bike coasts up, slowing as it climbs, and stops at the top.
The energy wasn’t lost. Motion, or kinetic energy, became height, or potential energy. Roll down the other side and that stored energy turns back into speed. The core lesson is that you can convert one form into a nearly equivalent amount of the other.
Trading airspeed and altitude in the airplane
In an airplane, airspeed and altitude play the same roles. If you’re slow on final but have a few hundred feet to spare, lowering the nose converts altitude into airspeed. If you’re low but fast, raising the nose converts some of that speed into a little altitude. How much you gain depends on what you start with.
Engine power adds a third tool. With power available, you can raise or lower the airplane’s total energy rather than just trading one form for another, within the limits of what the engine can deliver.
The energy state to avoid
Rod’s warning is about being both slow and low. With little airspeed and little altitude, the only way to add energy is engine power. If the engine has failed or can’t produce enough, you may end up in a stall without the altitude to recover. Good energy management means keeping enough kinetic and potential energy for the phase of flight you’re in, and Rod points to the stabilized approach as one of the best ways to do that.
Go deeper with Rod Machado
Rod builds on concepts like this throughout his eCourse on how to fly an airplane, linking the physics to the control inputs you’ll actually use. Learn more in How to Fly an Airplane eCourse.
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