AFH 4-1

Airplane Flying Handbook (FAA-H-8083-3C) Chapter 4: Energy Management: Mastering Altitude and Airspeed Control Introduction This chapter is all about managing the airplane’s altitude and airspeed using an energy-centered approach. Energy management can be defined as the process of planning, monitoring, and controlling altitude and airspeed targets in relation to the airplane’s energy state in order to: 1. Attain and maintain desired vertical flightpath-airspeed profiles. 2. Detect, correct, and prevent unintentional altitude-airspeed deviations from the desired energy state. 3. Prevent irreversible deceleration and/or sink rate that results in a crash. Importance of Energy Management Learning to manage the airplane’s energy in the form of altitude and airspeed is critical for all new pilots. Energy management is essential for effectively achieving and maintaining desired vertical flight path and airspeed profiles, (e.g., constant airspeed climb) and for transitioning from one profile to another during flight, (e.g., leveling off from a descent). Proper energy management is also critical to flight safety. Mistakes in managing the airplane’s energy state can be deadly. Mismanagement of mechanical energy (altitude and/or airspeed) is a contributing factor to the three most common types of fatal accidents in aviation: loss of control in-flight (LOC-I), controlled flight into terrain (CFIT), and approach-and-landing accidents. Thus, pilots need to have: 1. An accurate mental model of the airplane as an energy system. 2. The competency to effectively coordinate control inputs to achieve and maintain altitude and airspeed targets. 3. The ability to identify, assess, and mitigate the risks associated with mismanagement of energy. Viewing the Airplane as an Energy System The total mechanical energy of an airplane in flight is the sum of its potential energy from altitude and kinetic energy from airspeed. The potential energy is expressed as mgh, and the kinetic energy as ½ mV². Thus, the airplane's total mechanical energy can be stated as: mgh + ½ mV² Where, m = mass g = gravitational constant h = height (altitude) V = velocity (airspeed) A flying airplane is an “open” energy system, which means that the airplane can gain energy from some source (e.g., the fuel tanks) and lose energy to the environment (e.g., the surrounding air). It also means that energy can be added to or removed from the airplane’s total mechanical energy stored as altitude and airspeed. A Frame of Reference for Managing Energy State At any given time, the energy state of the airplane is determined by the total amount and distribution of energy stored as altitude and airspeed. Note that the pilot’s frame of reference for managing the airplane’s energy state is airplane-centric—being a function of indicated altitude and indicated airspeed, and not height above the ground or groundspeed. The indicated altitude displayed in the altimeter and its associated potential energy are based on the height of the airplane above a fixed reference point (mean sea level or MSL), not on the height above ground level (AGL), which changes with variations in terrain elevation. Likewise, the indicated airspeed displayed in the airspeed indicator and its associated kinetic energy are based on the speed of the airplane relative to the air, not on the speed relative to the ground below, which varies with changes in wind speed and direction.