What Are Attitude Indicators and How Do They Function on Aircraft?
Relying on a gyroscope, an attitude indicator is able to show the plane’s orientation with respect to both the longitudinal and lateral axes. Rotating the gyroscope around the longitudinal axis indicates the degree of bank or roll which is the degree to which the wings are level with each other. If one wing is angled further down than the other, it indicates a rolling motion of the plane to that side. Conversely, the lateral axis determines pitch which indicates whether the nose is angled up, down, or level. It is highly important for pilots to know the orientation of the plane as it affects their direction in the sky. However, when flying 30,000 feet above the ground, it is very hard to discern how the aircraft is oriented simply by eye. For this reason, pilots refer to the attitude indicator which is, in essence, a gyroscope.
In effect, the gyroscope works by measuring the ways the plane is oriented in comparison with a fixed point that always remains upright. By using a combination of gimbals and a free-spinning wheel suspended in the center, a properly working gyroscope should remain vertically upright while the aircraft rolls and pitches around it. As a result, there is always a stable point of reference to compare with the angle of the rest of the plane. To minimize any tilting caused by friction, a mechanism inside the instrument applies a force when the gyroscope tilts from its vertical position. Additionally, all mechanical gyroscopes have inner and outer bearings, along with a rotor assembly to further minimize friction. Bearings used here also contain aircraft bearing oil and are designed to operate at high RPMs.
While traditional airplanes used a fully mechanical gyroscope like the one described above, modern avionics often incorporate different methods in place of spinning parts. In fact, they have a version of an Attitude Heading Reference System (AHRS) or Air Data Attitude Heading Reference System (ADAHRS) where a plane’s altitude is calculated using two solid-state gyros, with one being set vertically and the other set horizontally. These gyroscopes are “solid state” because they do not involve any rotating parts, and instead, they use a vibrating element that can determine attitude based on changes in vibrational frequency caused by a change in orientation while moving (also called Coriolis acceleration). Though we will not cover it in detail in this blog, some older glass instruments might use a laser ring gyro (LRG), that of which is a gyroscope that uses the Sagnac Effect to determine pitch and bank information.
Regardless of which type of attitude indicator is used in an aircraft, the device always plays a crucial role as one of the six major indicators shown in a pilot’s flight display. Whether you are simply curious about the working principle of these devices or are in need of components for specific indicators for your aircraft, NSN Fulfillment invites you to explore our catalog of available aviation products. Backed by a widespread supply-chain network and unparalleled purchasing power, we find solutions for our customers’ fulfillment needs that can match all their deadlines and requirements. Discover aviation-grade equipment and components today and request quotes for your comparisons with ease on our website. At NSN Fulfillment, we will go above and beyond industry standards to bring you the best in product fulfillment!
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