What Is Meant by the 6 Pack of Flight Instruments?

What is meant by the 6 pack of flight instruments? Knowing what this term means is an integral part of understanding the role that instruments play in flight.

The “six-pack” of flight instruments refers to the six primary instruments found on every flight deck. These instruments are the most crucial for every flight and play a lead role when flying in conditions with less-than-optimal visuals.

Learning how to read the instruments is probably the most daunting part of learning how to fly. Thankfully, these instruments have an intuitive design, so you don’t have to decipher as much information as you might think.

A closer look at these instruments will help you learn more about what purposes these tools serve and how they help keep planes on course. You’ll be a better pilot by informing yourself about the critical role that these instruments play.

What Is Meant by the 6 Pack of Flight Instruments? A Quick Intro

The mechanics behind flight instruments are somewhat complicated, despite reading instruments being a relatively easy task. Another confusing thing about these instruments is that many of them have multiple names.

Understanding how these instruments work will help you understand the differences between them. These instruments include attitude, heading, and vertical speed indicators, the turn coordinator, and the altimeter.

Which Instruments Are Considered Gyroscopic?

The instruments that are considered gyroscopic include the attitude and heading indicators, as well as the turn coordinator. We will take a closer look at why these instruments are gyroscopic and what that means.

Electrical and Pneumatic Gyroscopes

Gyroscopic instruments use a mechanical gyroscope driven by electricity or pneumatically, which involves vacuum motion. Depending on the device, the gyroscope features a disc relating around a particular axis.

When a gyroscope features electric power, an electric motor controls the disc’s motion. Turn Coordinator is an example of an electronically-driven gyroscope.

Gyroscopes that use a vacuum system have an engine-driven vacuum pump that reduces pressure within the instrument case. Air passes over the disc at a high speed to help produce the motion required for the instrument to function as it is supposed to during the flight.

Are Gyroscopes Rigid in Space?

One of the things that make gyroscopes useful for instruments in airplanes is a concept known as rigidity in space. Another term for this concept is gyroscopic inertia.

If there are no external forces involved, the spinning disc will remain stable. As the speed of the disc or mass increases, the disc’s stability will also increase.

Because there are high speeds involved, the gyroscopes feature heavy-duty materials. The average rate for gyroscopes is about 10,000 Revolutions Per Minute (RPM).

Gyroscopes’ spinning discs can provide a measure of the aircraft’s attitude or orientation relative to the disc. The plane will move around the disc at the same time the frames around the disc, known as gimbals, move unhindered.

What is Precession Relative to Gyroscopes?

Precession is another phenomenon related to gyroscopes. Unlike many other circumstances where force is involved, precession does not include the object moving in the same direction as the applied force.

When precession occurs, the force will act 90 degrees in the direction of the spinning motion. The resulting movement is a turn or tilt instead of spinning in a different direction.

The friction inside a gyroscope and forces from acceleration or deceleration will cause precession. Because drifting that might cause incorrect readings is possible, pilots will need to be diligent about cross-checking their instruments.

Attitude Indicator/Artificial Horizon

An attitude indicator (AI) is also known as an artificial horizon (AH). This instrument is the most important for determining attitude or orientation in a plane.

The information that the AI provides is the bank and pitch angle relative to the horizon. Pilots can make the necessary adjustments when they are aware of the plane’s attitude.

The AI is a good indicator of information from other instruments, making the AI the foundation for the instrument scan. One example is that if the AI shows a bank angle, the Heading Indicator will show that a turn in the bank’s direction is necessary.

During Instrument Flight Rules (IFR), AI can be particularly helpful. The outside horizon might not be available, making AI particularly helpful.

The markings that AI displays make pitch and bank angle determination easier. These readings are measured with great accuracy, providing substantial help for pilots.

There are limits to vacuum-driven AIs of 60 degrees of pitch angle and 100 degrees of bank angle. When planes exceed these limits, the AI topples until the plane returns to angles within the limits.

The AI will return to its proper position once the aircraft returns to its pitch and bank limits. However, the gyroscopes will possibly take a few minutes to stabilize.

When is an Attitude Indicator Used?

An AI is indicated for use in poor weather conditions, such as poor visibility and low clouds. These conditions are the type where IFR rules are customarily in effect.

When flying under VFR conditions, the AI is not necessary in the way it is during poor weather. However, using an AI allows for greater situational awareness and better guidance if visibility declines during the flight.

Heading Indicator/Direction Indicator/Directional Gyro

The heading indicator (HI) may also be known as the direction indicator (DI) or sometimes the directional gyro (DG). This instrument serves as the primary indicator for the horizontal direction.

Care is necessary because the HI will have drift errors. A magnetic compass will be necessary to adjust the HI to the correct heading.

A heading bug feature is common in many HIs. This feature uses colored markers that a pilot can move to a heading in the HI for reference.

Although commonly mistaken for each other, the HI differs from the Horizontal Situation Indicator (HSI). The HSI is a variation of the HI that includes different settings not applicable to all flights.

When is a Heading Indicator Used?

The HI can be used to help find the runway when approaching an airfield. If the HI has been properly aligned, you’ll be able to find the runway easily.

Turn Coordinator/Turn and Bank Indicator

The turn coordinator, sometimes called a turn and bank coordinator is another crucial gyroscopic instrument. This instrument provides the bank angle and coordination information that pilots need.

Planes are considered to be in coordinated flight when the aircraft will not skid or slip in a turn because of the rudder input information. Another circumstance where planes are considered in coordination is when there is alignment with a tailplane on a straight flight.

A ball placed inside a liquid-filled tube inside the instrument helps provide this information. The ball can move to the right or left to give the pilot an idea of where rudder input is necessary.

A vertical line moving in the direction of the bank or a miniature aircraft provides bank angle information. Turn coordinators also have four white demarcations to provide additional information.

The demarcations help provide the bank angle for a standard rate turn, as well as a wings-level position indicator. Standard rate turns are three degrees per second and are most often used during Instrument Flight Rules (IFR) flights.

What Conditions Are Helpful for Turn Coordinators?

Turn Coordinators often prove helpful in adverse weather conditions. However, pilots must be careful not to maneuver the plane more quickly than is recommended.

What Are the Pitot-Static Instruments?

The pitot-static systems include the following:

• Airspeed indicator
• Altimeter
• Vertical speed indicator (VSI)

Pitot-static instruments measure the static and dynamic are pressure during a flight. Some of the information these instruments provide includes airspeed, vertical speed (also known as the climb and descent), and altitude.

These systems contain at least one pitot tube and static port. One of each is usually all that is necessary for general aviation aircraft.

Pitot tubes are positioned within relative airflow when a plane is in flight. Ram air pressure, which is almost equal to the total air pressure, is measured when air enters the tube by way of a small hole.

The air pressure measured with the pitot tube is often called pitot pressure. This air pressure measurement is distinguished between total and ram air pressure.

Most static ports, designed to measure static pressure, are mounted on the fuselage. Multiple static ports can be mounted around the aircraft for more accurate readings.

Pitot-static tubes have static ports built into the design. How this feature works is through holes unaffected by the airflow.

Airspeed Indicator

The airspeed indicator provides an accurate measurement of the plane’s speed. One of the most critical metrics during any flight is airspeed.

In addition to performance, the airspeed also affects the limitations of some systems on the plane. An example of systems that airspeed affects are the landing gear and flaps.

The pitot tubes and static ports allow the Airspeed Indicator to determine the dynamic pressure level. Both of these elements play an essential role in this pressure reading.

For a dynamic air pressure reading, static pressure is subtracted from the total pressure. Dynamic air pressure is an airspeed measure.

The airspeed indicator uses colored rings on a dial, which stand for different speed ranges. Green rings are indicators of average speeds, while white rings show the flap’s operating speed.

Yellow rings are for the caution range, which pilots should only enter if the air is calm. The red rings denote speeds that pilots should never exceed.

Altimeter

The altimeter indicates the plane’s altitude over the mean sea level (MSL). However, this instrument must be adjusted to an accurate barometric pressure setting.

Static ports on the plane provide the Altimeter with static pressure information. The altimeter contains expanding or contracting aneroid capsules that move gears and linkages for displaying altitude information.

Altimeters contain short and long needles, which serve a similar purpose to clock hands. The long needle measures hundreds of feet, while the short needle measures thousands of feet.

Vertical Speed Indicator

The vertical speed indicator (VSI) measures the rate of climb (ROC) or rate of decent(ROD)in feet per minute (fpm). Other names for this instrument may include vertical velocity indicator or variometer.

A VSI contains an aneroid capsule that can expand or contract based depending on altitude changes. On the VSI, the pressure difference is displayed as ROC or ROD.

One thing pilots need to be aware of is that the VSI is delayed compared to the altimeter. However, there are newer developments to the VSI that have mostly ended the lag.

How Do Pilots Learn About These Instruments?

Pilots learn about these instruments during a part of flight training, known as instrument flight training. The ultimate goal of instrument training is receiving an Instrument Rating, indicating your ability to navigate using only the instruments.

Instrument Rating training hours required can vary depending on the country where the pilot is seeking the rating. For American pilots, this training averages 100 hours using simulators and time spent in an aircraft.

Once you have your Instrument Rating, you will be able to fly IFR when conditions warrant these rules. If you lack an Instrument Rating, you will only be able to fly under Visual Flight Rules (VFR), which require the visibility to fly without using instruments.

If you intend to fly above a certain height, you will also typically have to have an Instrument Rating. Greater flexibility is available to you with a Flight Rating.

Instrument training will acquaint you with all the essential instruments highlighted earlier. The training allows you to learn each instrument’s function, how to read them, and how to identify and troubleshoot problems.

This training involves actual flight in the conditions where instruments are used or in simulator conditions. In either case, pilots will have a solid background in when and how to use these instruments.

What Do You Need to Get an Instrument Rating?

You must already hold a pilot’s license to get an Instrument Rating. Many instructors prefer to work with students already familiar with flying VFR.

The options available are flexible. You might receive intensive training in a flight school or private instruction with a flight instructor.

One of the goals of training is to provide the necessary flight hours. Another important goal is making sure that you are able to pass any other tests required before seeking your Instrument Rating.

Pilots flying under IFR should be competent after receiving their training. The broader the range of flight conditions a pilot is exposed to, the less likely they are to make serious mistakes.

FAQs

Final Thoughts

Now that you are familiar with the 6 pack flight instruments concept, you’ll have a greater appreciation for the role that the tools play.