Definition
The target combination of airspeed, altitude, and power setting that the pilot intends the airplane to be in for a given phase of flight. It represents the correct total energy (kinetic plus potential) and the correct distribution of that energy between speed and height for the maneuver being flown.
Plain English
The speed, altitude, and power the airplane should be at right now for what you are trying to do. If you are too fast, too slow, too high, or too low for the phase of flight, you are not in your desired energy state.
Context Anchor
Seen in energy management discussions when comparing the airplane’s actual height and speed with the height and speed it should have at that point in the maneuver or flight path.
Derivation
Energy comes from a Greek word meaning activity or work. In flying, it helps to think of energy as what the airplane has available to work with: height, speed, or a useful mix of both.
Why Pilots Care
Maintaining the desired energy state prevents unstable approaches, excessive float, hard landings, or the need for a go-around.
Analogy
It is like having a target speed and distance while driving toward a stop sign. You are aiming to arrive at the right place with the right amount of speed, not just any speed that happens to work for the moment.
Intuition Check
Do not read “desired” as simply “preferred” or “nice to have.” Here it means the target condition the airplane should be in for safe, controlled flight at that moment.
Example Sentence 1
On final approach, the desired energy state was 75 knots at 500 feet AGL with a stable descent rate, so when the airspeed crept up to 90 knots the pilot reduced power to get back on profile.
Example Sentence 2
After an energy deficit developed on base leg, the instructor added power to restore the desired energy state before turning final.