A pilot is flying a Localizer Back Course (LOC BC) approach using a standard VOR/LOC indicator. How should the pilot interpret the course deviation indicator (CDI) relative to the aircraft's position and the localizer course?
- AThe CDI provides normal sensing, indicating the direction to turn to the course.
- BThe CDI provides reverse sensing, meaning a left deflection indicates the course is to the right.
- CThe CDI provides reverse sensing, meaning a right deflection indicates the course is to the right.
- DThe CDI provides no reliable course guidance on a back course.
Show answer & explanationAnswer & explanation
Correct answer: B. The CDI provides reverse sensing, meaning a left deflection indicates the course is to the right.
When flying a Localizer Back Course (LOC BC) with a standard VOR/LOC indicator (not an HSI or flight director set for back course), the CDI exhibits reverse sensing. This means if the needle deflects to the left, the course is actually to your right, and you should turn right to intercept it. Conversely, a right deflection means the course is to your left, and you should turn left.
Why the other options are wrong
- A. Normal sensing occurs on a front course, not a back course with a standard indicator.
- C. A right deflection with reverse sensing means the course is to the left, not the right.
- D. The CDI does provide guidance, but it must be interpreted with reverse sensing.
Localizer Back Course Reverse Sensing
When flying a Localizer Back Course (LOC BC) using a standard VOR/LOC indicator (without an HSI or flight director set for back course), the Course Deviation Indicator (CDI) will exhibit reverse sensing. This means the needle's deflection indicates the direction opposite of where the course actually lies.
- Applies to standard VOR/LOC indicators on LOC BC approaches.
- Left CDI deflection means course is to the right.
- Right CDI deflection means course is to the left.
- HSI/flight director with back course mode provides normal sensing.
- Requires pilot mental adjustment or proper equipment setup.
Memory trick: Back Course is Backward!