Your Guide to Flight Controls

Having a deep understanding of flight controls and instruments are crucial for a safe flight. Here is what you should know.

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Flight controls are the actual instrumentation and items which pilots use to control an aircraft. They are the primary tools of the pilot. All aircraft, even gliders, have flight controls, but advanced airplanes offer pilots a wide variety of ways to fine tune the direction, attitude, and altitude of an aircraft. Strong command of the controls and flight control surfaces is one of the many determiners which separate an accomplished commercial pilot from a new student pilot. Good pilots understand how to use all these controls in concert with one another to provide efficient take off, cruise, and landing.

 

What Are Flight Controls?

Flight controls help the pilot in command (PIC) or the crew manage the airplane throughout all aspects of flight. They are specially designed to work with the forces of physics as they apply to the airplane. Controls are conceived, fashioned, refined, and tested by a team of experts. Aeronautical engineers, test pilots, airplane mechanics, human factors experts, computer programmers, electrical engineers, and material scientists all have a part in developing safe and effective controls.

Even the first aircraft had flight controls that were necessary to exercise any command over the airplane. Since computers were far in the future and it was an enormous struggle to achieve lift over the airframe and engine’s own weight, these were rudimentary. Powerful aircraft require more control due to its expanded capabilities. More advanced modern airplanes contain hydraulic arrangements, automated systems, and fiber optics. Airplanes which are guided by computers connected to the controls are said to “fly by wire.” While these systems are generally more efficient, safer, result in a lower workload for pilots, and can be easier for mechanics to diagnose, fly by wire systems are usually far more costly than traditional controls.

Today, controls are highly variable depending upon which aircraft they are mounted. A tiny sports plane for example, will by necessity contain far fewer and far simpler flight controls than a military fighter jet. In addition, on passenger airplanes, one of the main objectives is to achieve lower weight to command savings in fuel costs, so the controls reflect this goal. The principles which drive all these designs, however, are the same.

 

General Principles of Controls

Understanding the principals behind flight controls demands a good comprehension of the three axes of flight. These are:

Lateral:

The pitch of the airplane, or the line extending from one wingtip to the other. This is also known as the pitch or transverse axis. It reflects the ability of the airplane to point the noise “up and down”. This axis of flight is necessary to pull the nose up to achieve lift in order to leave the ground or increase altitude. When it is time to descend to a lower altitude or land, the nose of the airplane is pitched down. Command of this axis was one of the most critical aspects of powered human flight to master.

Vertical:

Another name for the vertical axis is the yaw or normal axis. Although, like the other aircraft axes, its origin is at the center of gravity, its line is formed at a right angle to the wings of the airplane. Working with this axis of flight allows the airplane to turn to the right and left, or “twist” to one side or another. The vertical axis is necessary for navigation and changing direction in flight. It might sometimes seem like it on a big passenger jet, but airplanes do not move along a straight line.

Longitudinal:

When an airplane rolls, it is moving along its longitudinal axis. This is the line running from the airplane’s nose to its tail; for obvious reasons, it is also called the roll axis. This movement along the lateral axis is important for banking. Turning in a commercial aircraft seems like it takes some time compared to an aerobatic airplane, and pilots are expected to do so as smoothly as possible. The rate of roll in a small general aviation airplane like a Cessna, however, is usually about the same as that on a large passenger jet.

 

Primary Flight Controls

An airplane’s primary flight controls work with the three axes of movement. Together, they control the basic movements of the aircraft. These are the:

• Ailerons
• Elevator
• Rudder

Their objective is to govern the airflow and distribution of air pressure around the aircraft. The primary flight controls affect drag as well as lift.

An airplane’s ailerons works with the airplane’s lateral axis to control pitch. They are usually mounted on the back of the airplane on the “tail,” or the horizontal stabilizer. The vertical axis is managed by the rudder, which is typically hinged and moved by two pedals at the pilot’s feet. Finally, the longitudinal axis is regulated with the ailerons. These are mounted to the edges of the wings and when one is raised, the other is lowered, and vice versa.

 

Secondary Flight Controls

Secondary flight controls aid or support the primary controls. They are not necessary for an airplane to safely take off, cruise, and land. However, they do make its flight more efficient and improve its performance. Secondary controls were added to airplanes after early aviation pioneers proved that powered flight was possible.  Depending on the flight school, once a student pilot is comfortable with primary flight control systems, his or her flight instructor will sometimes begin to introduce secondary controls. Others teach both types of controls at the same time.

Secondary flight controls include:

• Flaps
• Leading edge devices
• Spoilers
• Trim systems

Flaps are relied upon during takeoff and landing; they help the pilot manage lift as efficiently as possible. Leading edge devices are slats, flaps, and cuffs. These are attached to or are part of the wing and decrease its angle of attack, which is important in delaying the onset of a potentially dangerous stall. Spoilers reduce lift and are important during descent and deceleration to slow down, while trim systems help the aircraft to maintain its altitude.

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