What is B/CRS on Boeing 737? (Back Course)

When it comes to aviation, there are countless technical terms and abbreviations to familiarize oneself with. One such abbreviation commonly used in the context of Boeing 737 aircraft is B/CRS, which stands for Back Course. So, what exactly is Back Course on Boeing 737? In this article, we will explore the concept of Back Course and its significance in the world of aviation.

Understanding Back Course

Back Course, or B/CRS, refers to a navigational aid utilized during certain instrument approaches for landing an aircraft. It is particularly relevant in situations where an aircraft needs to land on a runway opposite to the one intended for use during normal operations. In other words, Back Course allows an aircraft to approach a runway from an opposite direction than the traditional one, making it an essential tool for pilots in specific situations.

During a Back Course approach, the navigation equipment on board the aircraft is set to track the localizer signal in reverse. The localizer is a ground-based radio transmitter that emits a signal that helps the pilot determine their alignment with the centerline of the runway. By reversing the navigation equipment’s tracking, the pilot can accurately fly the aircraft along the centerline, even when approaching from the opposite direction.

Back Course is typically used when a runway lacks the necessary instrument approaches for landing in the opposite direction. In such cases, pilots rely on the back course functionality to safely align themselves with the centerline of the runway and execute a successful landing. It’s important to note that not all runways are equipped with back course capabilities, so pilots must be familiar with the available navigation options at their destination airports.

Back Course Instrument Approach Procedure

Now that we understand the concept of Back Course, let’s delve deeper into the instrument approach procedure associated with its usage on Boeing 737 aircraft. The instrument approach procedure for Back Course involves several key steps:

  • The pilot selects the Back Course mode on the Flight Management System (FMS) or the navigation receiver to enable the tracking of the localizer in reverse.
  • Upon interception of the localizer signal, the aircraft starts tracking in the back course mode. Pilots monitor the Course Deviation Indicator (CDI) or the Horizontal Situation Indicator (HSI) to ensure proper alignment.
  • The pilot follows the glide slope indications to maintain the correct vertical profile during the approach.
  • As the aircraft approaches the runway threshold, the pilot transitions to visual references for landing, aligning with the centerline and adjusting the aircraft’s descent rate accordingly.
  • Finally, the pilot executes a smooth touchdown, bringing the aircraft to a complete stop on the runway.

It is crucial for pilots to adhere to the specific procedures laid out by the aircraft manufacturer and aviation authorities when performing a Back Course instrument approach. This ensures safety and consistent execution across different Boeing 737 aircraft.

Advantages and Limitations of Back Course

While Back Course can be a valuable tool for pilots in specific situations, it also comes with certain advantages and limitations. Let’s explore these:

Advantages of Back Course

1. Increased flexibility for landing: Back Course allows an aircraft to land on a runway opposite to the one typically used, providing increased flexibility to pilots, especially in challenging weather conditions or when alternate runways are required due to maintenance or other factors.

2. Simplified airspace management: By enabling landing on an opposite runway, Back Course helps in better management of airspace and reduces congestion during high traffic periods.

3. Enhanced operational efficiency: Back Course can facilitate shorter and more direct approaches to certain runways, optimizing flight paths and reducing fuel consumption.

Limitations of Back Course

1. Limited availability: Not all runways are equipped with back course capabilities, which limits its applicability in certain scenarios. Pilots must verify the availability of Back Course capability at their destination airports or alternate airports during flight planning.

2. Increased monitoring and attention required: Back Course approaches demand heightened attention from pilots, as they need to monitor the reverse-tracking navigation equipment closely while ensuring proper alignment with the centerline and glide slope.

3. Potential interference: The reverse-tracking nature of Back Course can sometimes lead to interference from nearby buildings, terrain, or other obstacles. Pilots must be aware of these potential challenges and take appropriate corrective actions if necessary.

In conclusion, Back Course, or B/CRS, plays a significant role in the aviation industry, particularly for pilots operating Boeing 737 aircraft. By allowing landing on runways in the opposite direction, Back Course provides increased flexibility and better airspace management. While it offers advantages such as enhanced operational efficiency, pilots must also consider the limitations and exercise caution during Back Course approaches. Familiarity with the specific procedures and equipment on board the aircraft is essential for safe and successful execution.

For more information on Back Course and instrument approaches, you can refer to the Federal Aviation Administration (FAA) website or consult the aircraft manufacturer’s documentation.

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