Commercial pilots looking to advance their careers with a first officer role in a regional airline look forward to flying the aircraft by looking out the window. But that’s only possible when the weather is perfect. But when flying at night or in clouds, gyroscopic instruments are essential to orient the aviator, be it an artificial horizon, gyrocompass, or turn and slip.
While reading the instrument is relatively straightforward for experienced commercial pilots, certain differences in acronyms or names can cause unnecessary confusion. In order to avoid complications and ensure safe operations, pilots must be equipped to understand flight instruments and take proactive decisions when they aren’t not working properly.
A refresher on these instruments by experts at Momentum Flight Training makes you a more proficient pilot, laying the groundwork for more advanced procedures as you move closer toward your dream of transiting to a regional airline pilot.
The Gyroscopic Instruments
Heading Indicator, Turn Coordinator, and Attitude Indicator are collectively known as gyroscopic instruments. They use a mechanical gyroscope that’s either electrically or pneumatically driven.
The first principle that makes gyroscopes suitable for flight instruments is their rigidity in space. Also known as gyroscopic inertia, the rigidity in space results from the disc spinning inside the mechanical gyro. The disc maintains a constant attitude as long as any external forces don’t act upon it. This stability increases as the disc’s speed or mass increases.
Since the spinning disk maintains a constant position in space, it’s useful in determining the attitude of the aircraft relative to the spinning disc. The aviator effectively moves around the disc as the gimbals move freely.
Besides rigidity in space, precession is another phenomenon experienced by a gyroscope. When force is applied to the spinning disk, it doesn’t act in the applied position but rather precesses 90 degrees in the rotation’s direction. So when force is applied to the spinning disc, it turns or tilts. The precession is caused by friction within the gyroscope and other forced experiences during deceleration, acceleration, and other maneuvers.
The precession, however, can result in the gyroscopic instruments causing a drift leading to incorrect readings. Therefore, you must constantly crosscheck and adjust the indications of these gyroscopic instruments.
The Attitude Indicator
Commonly referred to as the Attitude Indicator as well as the Artificial Horizon, this instrument provides information on the aviator’s pitch angle and bank angle in relation to the horizon with great accuracy.
You can use this to interpret and adjust the aircraft’s attitude. It’s particularly useful during Instrument Flight Rules (IFR) flights where the outside horizons might not be available. The vacuum-driven attitude indicators are usually limited to 60 degrees pitch and 100 degrees bank angle.
When the limits are exceeded, the AI can topple until the aviator returns its bank and pitch angle within limits and the attitude indicator regains the correct position. This could take anywhere between a few seconds to several minutes to stabilize enough for the instrument to indicate decorously.
The Heading Indicator
Also known as Directional Gyro and Direction Indicator, the Heading Indicator acts as the aircraft’s primary horizontal direction indicator. The HI often suffers from drift errors, so it needs to be corrected periodically using a magnetic compass.
Don’t confuse it with the Horizontal Situation Indicator, as that’s an evolution of the HI and includes ILS and VOR indications.
The Turn Coordinator
Also known as the bank and turn indicator, the TC is another development of the slip and turn indicator, which provides information regarding the angle of the bank and the aircraft’s coordination.
The aviator is in coordinated flight when the rudder input averts it from skidding or slipping during turns or when the tailplane is aligned with the flight path during a straight flight. A ball located in a fluid-filled tube is used to display the information. For example, when the ball is displayed on the right, pilots know the right rudder input is required.
A vertical line or miniature aircraft rotating in the bank’s direction also provides information about the bank angle. The turn coordinator comprises white demarcations that indicate the position of wings-level and the required bank angle for a standard rate one turn.
Pitot-Static Instruments
This system is used to measure the dynamic and static air pressure during flight. The data helps determine the descent or climb rate, airspeed, and altitude. It comprises static ports and pitot tubes, although usually, one of each is needed.
The pitot tube is positioned into the relative airflow in flight. The pressure measured by the pitot tube is often called pitot pressure to prevent confusion between total and ram air pressure.
Static ports are mounted on the aircraft’s fuselage to measure static pressure. For greater accuracy, multiple ports can be mounted around the aviator. Some aircraft also have pitot-static tubes that incorporate static ports into the pitot tube.
Pitot static systems are based on an altimeter, vertical speed indicator, and airspeed indicator.
The Airspeed Indicator
Simply put, the airspeed indicator measures the speed of an aircraft in the air. It’s a critical in-flight metric because the instrument helps determine its performance. Moreover, many systems, such as caution, operation, flap setting, and landing gear, have limitations based on airspeed.
Both pitot tubes and static ports are used by the airspeed indicator to evaluate dynamic pressure. The static port pressure reading is then subtracted from the total pressure pitot tube reading to get dynamic pressure.Â
Altimeter
The altimeter, when adjusted properly according to the barometric pressure setting, indicates the altitude of the aviator above Mean Sea Level. Altitude meters use information from the static ports to evaluate the static pressure.
The aneroid capsules inside the instrument contract or expand based on the static pressure, moving a series of gears and linkages to display accurate altitude information. The short needles on the altimeter indicate thousands of feet, whereas hundreds of feet are indicated by long needles.
Vertical Speed Indicator
The VSI uses the aviator’s static ports to identify the Rate of Descent or the Rate of Climb in feet per minute. Some pilots refer to VSI as a vertical velocity indicator or a variometer. The aneroid capsule within the VSI contracts and expands based on the altitude change, and the rate of change of pressure can be measured and displayed on the vertical speed indicator as an ROC or ROD.
It can be slightly delayed, lagging behind the altimeter, so you must consider this when making adjustments based on this instrument’s readings. VSI was further developed and can use accelerometers to emulate the instrument’s lag. This is known as Instantaneous Vertical Speed Indicator.
If you want to refresh your knowledge or smoothen your transition into regional airlines, Momentum Flight Training is offering 1-day, 3-day, and 5-day aircraft simulator training programs targeted at improving the skills and proficiency of aspiring regional pilots.
The training institute uses a top-of-the-line CRJ simulator with realistic components and systems that reflect the original deck flight environment of Canadair Regional Jets 200, 550, 700, and 900.
Their qualified instructors prepare two students per class through operational training, flows, call-outs, systems, and other procedural training using an Advanced Aviation Training Device.
If you are moving upward and beyond to the regional airlines and will be flying the CRJ, call [833] 427-5876 for more information on their pre-set programs or speak to a qualified instructor for tailored programs that effectively meet your learning goals.
About the Author Samantha’s aeronautics career spans over two decades. She has accumulated 25,000 hours of flight time and worked as an FAA examiner, along with finishing captaincy at a popular regional airline. She likes to write about the latest happenings in aviation and plans to write her own book, eventually.
