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What is the purpose of a course deviation indicator?
A course deviation indicator (CDI) is an avionics instrument used in aircraft navigation to determine an aircraft’s lateral position in relation to a course to or from a radio navigation beacon. If the location of the aircraft is to the left of this course, the needle deflects to the right, and vice versa.
What causes reverse sensing?
In “reverse sensing,” the instrument is displaying exactly what you’re telling it to display. It takes some effort from the pilot to not become “reversed.” Where pilots get confused and think that the instrument is reversed is when the OBS is set to the reciprocal of the course they want to fly.
Can an HSI reverse sense?
Reverse sensing occurs when the current heading is on the bottom half of the VOR. Taking this theory to the HSI where the currently flown heading is always on the top half and you can never have reverse sensing. It is also proper technique to set in the front course when flying a LOC/BC approach.
How do we avoid reverse sensing?
To avoid reverse sensing, remember that radials are always radiating away from the VOR station. So, you normally want a From indication. The exception is when you are specifically told to fly directly to a station or track a radial inbound. Then you are going to the VOR, and you want a To indication.
How do you use a course deviation indicator?
Use. The indicator shows the direction to steer to correct for course deviations. Correction is made until the vertical needle centres, meaning the aircraft has intercepted the given courseline. The pilot then steers to stay on that line.
What is reverse sensing HSI?
Reverse sensing occurs on the back course using standard VOR equipment. With a horizontal situation indicator (HSI) system, reverse sensing is eliminated if it is set appropriately to the front course.
How does the course deviation indicator ( CDI ) work?
The instrument that displays all of this information is most commonly called the Course Deviation Indicator, or CDI. The Omni-Bearing Selector (OBS) knob lets you select one of these spokes (radials), and the CDI will tell you where you are in relation to your selected radial.
When do pilots get confused with reverse sensing?
In “reverse sensing,” the instrument is displaying exactly what you’re telling it to display. It takes some effort from the pilot to not become “reversed.” Where pilots get confused and think that the instrument is reversed is when the OBS is set to the reciprocal of the course they want to fly.
When does the course deviation needle move to the right?
If the course selector is rotated until the deviation needle is centred, the radial (magnetic course “FROM” the station) or its reciprocal (magnetic course “TO” the station) can be determined. The course deviation needle also moves to the right or left if the aircraft is flown or drifting away from the radial which is set in the course selector.
Do you get reverse sensing on a localizer?
As long as you tune the front course for the localizer, you won’t get reverse sensing. When configured properly, you can fly the LOC BC approach with normal sensing, and fly “to the needle” like you do in all other navigation.