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What is BC in Aviation? (Back Course)

Updated: March 03, 2024

The Back Course (BC) - A Guide to Understanding this Aviation Term

Aviation is a complex and fascinating field, filled with various terminologies and acronyms that can sometimes be overwhelming for newcomers. One such term that pilots and aviation enthusiasts often encounter is the Back Course (BC). In this article, we will explore what the Back Course is, its significance in aviation, and how it is used in practice.

What is the Back Course (BC)?

The Back Course, abbreviated as BC, refers to an instrument approach procedure used in aviation. It is typically associated with Instrument Landing Systems (ILS). An ILS is a ground-based navigational aid that provides guidance to pilots during the final approach phase of landing. It consists of two main components: the localizer and the glide slope.

When an aircraft is approaching an airport, it aligns itself with the runway centerline using the localizer. The glide slope, on the other hand, provides vertical guidance to the aircraft, ensuring that it maintains the correct descent rate for a safe landing. The Back Course, however, is an exception to this standard approach.

The Back Course is essentially the reverse of a normal ILS approach. Instead of the aircraft flying towards the runway, it flies away from it, following the opposite heading. This means that the localizer, which typically guides the aircraft towards the runway, is now used to guide the aircraft away from it. The Back Course is primarily used as a backup or alternative approach when the primary approach is unavailable or out of service.

When is the Back Course Used?

The Back Course is used in specific situations where the primary ILS approach is not available or when aircraft need to make an approach from the opposite direction. Here are a few scenarios where the Back Course may be utilized:

Primary ILS Out of Service: If the primary ILS approach to a runway is temporarily out of service due to maintenance or technical issues, the Back Course can serve as an alternative approach for pilots. It allows them to still make a safe landing using the ILS system, albeit in reverse.
Direct Entry to Final Approach: In some instances, air traffic control may direct an aircraft to enter the final approach directly, without following the standard arrival procedures. In such cases, the Back Course can be used to align the aircraft with the runway centerline, ensuring a smooth and accurate landing.
Non-Precision Approaches: While ILS approaches provide highly accurate guidance, certain airports may not have full ILS installations. Instead, they may have non-precision approaches such as a VOR (VHF Omnidirectional Range) or an NDB (Non-Directional Beacon). In such cases, the Back Course can be used to simulate an ILS approach by using the localizer component of the ILS system.

It is important to note that the Back Course should only be used when authorized by air traffic control or when it is published as a valid approach procedure in the airport's instrument approach charts.

How is the Back Course Flown?

When flying the Back Course, pilots follow a specific procedure to ensure a safe and accurate approach. Here is a step-by-step guide on how the Back Course is typically flown:

Intercept the Localizer: As with a normal ILS approach, pilots must first intercept the localizer signal. However, instead of tracking the localizer towards the runway, they will track it away from the runway. This will result in the aircraft flying in the opposite direction.
Monitor the Course Deviation Indicator (CDI): The CDI is an instrument on the aircraft's cockpit display that shows the deviation from the desired course. When flying the Back Course, the CDI will indicate the aircraft's position relative to the localizer. Pilots must carefully monitor the CDI to ensure they remain centered on the localizer.
Monitor the Glideslope Indicator (if available): In some cases, an ILS may still provide a glideslope indication for the Back Course. Pilots must monitor the glideslope indicator to maintain the correct descent rate, just as they would during a normal ILS approach.
Execute the Missed Approach Procedure: If, for any reason, the pilot decides to discontinue the Back Course approach or encounters any issues during the approach, they must be prepared to execute the missed approach procedure as specified in the approach charts.

It is crucial for pilots to be well-trained and knowledgeable about the Back Course procedure before attempting to fly it. Proper understanding and adherence to the procedure ensure a safe and efficient approach to the runway.

Aviation is a constantly evolving field, and it is important for pilots to stay updated with the latest procedures and regulations. The Back Course is just one of the many terms and techniques that pilots must be familiar with to ensure safe and successful flights. By understanding the Back Course and its applications, pilots can confidently navigate various situations and make informed decisions during their flights.

For more information on ILS approaches and the Back Course, refer to the Federal Aviation Administration (FAA) website or consult the relevant aviation publications and training resources.

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