AUTOMATIC FLIGHT CONTROL AND
STABILIZATION SYSTEMS
Aircraft fly under many conditions. External
pilots have duties other than moving the flight
controls. However, regardless of how sophisti-
conditions can alter the desired flight charac-
cated the AFCS computer may be, the reasoning
teristics of the aircraft. To maintain the desired
power of the pilot cannot be duplicated.
characteristics of the aircraft, the pilot moves the
control surfaces either manually or automatically.
You have already learned about indicating
systems and instruments that supply the pilot with
PRINCIPLES OF FLIGHT
information on the performance of the aircraft.
The pilot must be able to see and interpret each
Learning Objective: Recognize principles
of these indicators, and then react to get
of flight for both fixed- and rotary-wing
the desired performance. In high-performance
aircraft.
aircraft, especially in single-piloted aircraft, other
flight duties require much of the pilot's time.
To understand automatic flight control and
Navigation, communication, radar, and other
stabilization systems, you must study the effects
special equipment is severely limited if the
that the various controls have on the aircraft.
pilot has to work consistently on the physical
Airman, NAVEDTRA 14014, contains a basic
manipulation of the controls.
introduction to the principles of flight and flight
controls. You should review this text before
In high-performance aircraft capable of
proceeding with this chapter.
supersonic flight, aircraft speed is so great that
the pilot's normal response time is far too slow.
An airfoil is any part of an aircraft designed
By the time the pilot reacts to an indicator to
to produce lift. Obviously a wing is the primary
position a control surface, the aircraft may
airfoil on an aircraft; but, propeller blades, tail
already be out of control.
surfaces, and even the fuselage itself are important
airfoils. The design of a specific airfoil is
Automatic flight control and stabilization
determined by the job it is to do. All airfoils have
systems ease the pilot's workload and provide
the basic elements shown in figure 8-1.
aircraft stability at all speeds. The information
now flows directly to a flight control computer
rather than to an indicator. This action lessens
the time required to start a control movement to
nearly zero (increased stability). The system
also provides command controls by which the
computer can control the aircraft in nearly any
desired flight condition. Some automatic flight
control systems are capable of flying the aircraft
to radio navigation aids, correcting for wind, and
making pilot-unaided landings.
The terms automatic flight control system
(AFCS) or automatic stabilization equipment
( A S E ) are used instead of the older term
automatic pilot, or the shortened version,
Figure 8-1.-An airfoil.
autopilot. A reliable AFCS is necessary because
