Why Are Magnetic Compasses Important for Aviation Operations?
Within a modern aircraft, pilots take advantage of numerous instruments and systems to obtain the information and readings necessary to carry out safe flight operations. Among all tools that are at one’s disposal in the cockpit, one item that often goes overlooked for its importance is the magnetic compass. This instrument provides crews with a simple and reliable means of obtaining crucial directional information during flight, allowing it to remain a staple of design, even in glass cockpits. To answer some of the biggest questions surrounding magnetic compasses in the context of aviation, read on as we discuss them in more detail.
What Is a Magnetic Compass?
Unlike other instruments that rely on onboard systems or satellite information to conduct measurements and provide readings, the magnetic compass is a simple, mechanical device that relies on Earth’s magnetic field to indicate heading. While various forms of technology have advanced rapidly over the years with sophisticated avionics and electronic flight systems now being a staple of design, the technology and working principle behind magnetic compasses has remained the same throughout history.
How Do Magnetic Compasses Work?
Put simply, a magnetic compass works by taking advantage of materials that are naturally drawn to Earth’s magnetic field to indicate direction. Within the housing of a compass, a magnetized needle or compass card will be mounted on a pivot, allowing it to rotate freely. The needle will naturally point toward the magnetic north pole regardless of its orientation, providing pilots with directional reference. To read a compass, one compares the orientation of the needle on a dial that is marked with radial degrees and cardinal directions. By referencing the compass, one can determine their heading relative to magnetic north, which is useful for navigation on the ground or in the air.
When Do Pilots Use Magnetic Compasses?
These instruments are primarily used in situations where electronic navigation systems fail or are otherwise unavailable to the pilot. Despite the widespread adoption of advanced equipment like GPS and inertial navigation systems (INS), the magnetic compass remains a reliable backup tool in case of an emergency. Pilots can always depend on it for directional reference regardless of power, ensuring that they can safely maintain course. For this reason, the magnetic compass is a required instrument in every aircraft, guaranteeing redundancy in the cockpit.
The magnetic compass also serves as an excellent cross-reference tool for pilots to verify the accuracy of other navigation instruments. For example, pilots can compare the heading provided by digital displays of a glass cockpit with the reading on their magnetic compass as necessary, allowing them to guarantee that all systems are functioning properly. Although a modernized cockpit offers numerous advantages in terms of situational awareness, the magnetic compass still provides an extra layer of confidence and redundancy to increase safety.
Do Magnetic Compasses Face Errors in Measuring Heading?
Despite their reliability, it is important to be aware of common situations in which the readings of magnetic compasses become erroneous. For example, when aircraft accelerate or decelerate, resulting force may cause the compass card of the instrument to temporarily shift, affecting readings. This effect is most prominent when flying near the magnetic equator, being a result of the pendulous nature of compasses that cause them to tilt slightly when forces other than magnetism are applied. Pilots must be aware of these acceleration errors, ensuring that they accommodate for their presence when trying to cross-reference readings.
Turning errors also occur when using a magnetic compass, as the change or orientation will detract from the magnetic needle’s ability to respond to magnetic forces. For example, if the aircraft banks, the changed gravitational forces that the needle will have to act against will cause inaccuracies. Compasses work best when level and flat, so pilots should keep this in mind at all times when using the instrument.
What Is Magnetic Deviation?
While temporary inaccuracies can occur during flight maneuvers, there is also magnetic deviation to contend with. This refers to magnetic fields generated from nearby aircraft systems that interfere with the accuracy of the compass. To mitigate this, pilots will regularly use a deviation card that is calibrated for their specific aircraft to account for all known interference. Regular checks and calibrations of any compass system are also essential to ensure its continued accuracy and reliability, particularly in older aircraft that may experience more significant interference from onboard systems.
Conclusion
Despite continued technological advancement, the magnetic compass remains an essential navigation tool in aviation as a result of its reliability as a backup navigation instrument. If you are currently in search of a reliable source of high-quality aircraft instrumentation, avionics, and more, look to Accelerating RFQs and our expansive product selection. Here, we feature over 2 billion new, used, obsolete, and hard-to-find items, all of which can be purchased at any time. Take the time to explore our offerings as you see fit, and be sure to make use of our online Request for Quote (RFQ) forms for the means of obtaining tailored procurement options from our team of industry experts.
