why does an hsi take away back course reverse sensing

by Hollie Moen 7 min read

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.

ILS Back Course Approaches
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.

Full Answer

How does reverse sensing work on Hsi?

While there is still a to/from indication for the VOR, the HSI will correct for any reverse sensing and show where you are in relation to that radial. So if the CDI needle is deflected to the right, you are always left of course (regardless of the to/from indicator). HSI’s Showing GPS Course

How does the HSI work?

horizontal situation indicator (HSI) ... It also gives standard sensing and course deviation indication on back course ILS approaches provided the front course heading is set under the head of the course pointer and you fly toward the course deviation indicator. Provides convenient 45° tic marks to help visualize procedure turns and ...

Is that “reverse sensing”?

May 10, 2016 · Is that “reverse sensing”? Well, not really because the needle just goes to the left when you’re in the shaded area. It doesn’t know front from back courses, or inbound from outbound. It only knows which side of the localizer feather it’s on. It’s actually just your senses that have to be reversed to correct properly.

What is a Horizontal Situation Indicator (HSI)?

Mar 31, 2017 · It sucks when you get this backwards when flying a backcourse. Of course, IRL, you pretty quickly realize that the needle reacts backwards from what you expect, and you can mentally note "reverse sensing" and then go on. But you'll have to disengage the autopilot, 'cause it will turn away from the selected course.

Why does HSI not have reverse sensing?

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.Feb 22, 2016

When flying a localizer back course approach using an HSI which course should be set in the OBS?

Rule #1. Always (always!) put the localizer inbound front course under the omni-bearing selector (OBS). The OBS setting doesn't matter to the electronics on a localizer, but this is a good rule as we'll see a bit further down.Jun 8, 2016

Why does reverse sensing happen?

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.Dec 23, 2015

What is the function of HSI?

The horizontal situation indicator (commonly called the HSI) is an aircraft flight instrument normally mounted below the artificial horizon in place of a conventional heading indicator. It shows the heading, course, bearings and the lateral deviation of an aircraft.

What is the difference between HSI and CDI?

Whereas a traditional CDI will only show your deviation to a given VOR radial, an HSI will show both your present heading and lateral position in relation to a VOR radial or GPS course line and doesn't have the potential for reverse sensing.

How do you fly with an HSI?

1:244:12Intercepting and Tracking with an HSI - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd this means that aircraft is west of that bearing or west of that line and according to theMoreAnd this means that aircraft is west of that bearing or west of that line and according to the needle which is five dots to the right. We are 10 degrees west of the 3 to 0 bearing to the station.

How do I stop reverse sensation?

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.Dec 5, 2000

How do you teach Reverse Sensing?

1:074:46VOR Navigation - YouTubeYouTubeStart of suggested clipEnd of suggested clipYou want reverse sensing. So either flip there will be a selection to the reciprocal. Or if theMoreYou want reverse sensing. So either flip there will be a selection to the reciprocal. Or if the needle goes left and you go right and vice-versa.

What is a back course approach?

What Is A "Back Course" Approach? When you fly a localizer back course approach (LOC BC), you're navigating to the runway using horizontal guidance off of a localizer system, but in the opposite direction that you'd normally use the localizer.Mar 24, 2018

What does HSI mean college?

A Hispanic-Serving Institution ( HSI ) is defined as an institution of higher education that— (A) is an eligible institution; and. (B) has an enrollment of undergraduate full-time equivalent students that is at least 25 percent Hispanic students at the end of the award year immediately preceding the date of application ...Apr 11, 2016

What makes an HSI easier?

In addition, an HSI makes it easier to visualize the aircraft's position with reference to the selected course or holding patterns. The "split needle" presentation made up of the course and reciprocal pointers and the VOR/LOC deviation indicators, clearly shows both selected course and course deviation.

What is the purpose of the course deviation bar in the HSI?

The HSI has a fixed aircraft symbol and the course deviation bar displays the aircraft's position relative to the selected course. The TO/FROM indicator is a triangular pointer: When the indicator points to the head of the course select pointer, the arrow shows the course selected.

What does the VOR instrument tell you?

The instrument always tells you the relative position to the VOR course / localizer, it is up to the pilot to manipulate the plane to the desired position. It's reverse tracking, not reverse sensing. The instrument tells you your deviation from the selected course , it has been and will be doing that all the time.

What is it called when you fly 180 degrees off?

It is worth noting that the autopilots have an "reverse course tracking" switch: If you want an instrument which tells you how to fly to intercept the course, it is called a Flight Director .

When does positive sensing occur?

For conventional VORs, Positive sensing occurs when the headng currently being flown is on the top half of the VOR. Reverse sensing occurs when the current heading is on the bottom half of the VOR.

When flying inbound on the back course, is it necessary to steer the aircraft in the direction opposite the needle def

According to the AIM, "when flying inbound on the back course it is necessary to steer the aircraft in the direction opposite the needle deflection when making corrections from off-course to on-course. This 'flying away from the needle' is also required when flying outbound on the front course of the localizer.".

Can you reverse sensing 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.

What is HSI in music?

The HSI is an improvement on the standalone CDI instrument in that it takes into consideration your actual heading. The old CDI would just have a radial set in the OBS and show your deviation (which could have reverse sensing depending on which radial you tuned) in relation to that radial. The HSI serves as a heading indicator as well as a CDI ...

What is CDI in navigation?

A CDI can be its own standalone instrument used for VOR navigation, or it can be part of an HSI which also integrates a heading indicator. When part of an HSI, the CDI is more just the actual course deviation needle on the instrument rather than the entire instrument itself.

Why is CDI confusing?

The reason the CDI can be a little confusing is because it can either be its own standalone instrument (used for VOR navigation) or it can be a component within an HSI (Horizontal Situation Indicator).

Can you reverse sensing a CDI needle?

Because of this there is a real downside to the standalone CDI instrument and that is you can have reverse sensing.

Does the heading bug control HSI?

It’s incredibly flexible because of this and I never have any reverse sensing in the cockpit. The heading bug does not control anything in the HSI per se, but is more of a “target” you can set if you are assigned a heading by ATC or if you are trying to remember your wind correction angle when tracking a VOR.

Is reverse sensing a malfunction?

It isn’t a malfunction of the instrument, just something you have to be keenly aware of particularly when flying IFR. As you can tell (or as you might know from personal experience), the potential to have reverse sensing in the cockpit can lead to some major issues.

What is an Hsi?

WHAT'S AN HSI? An HSI, or Horizontal Situation Indicator, is a combination of two familiar cockpit instruments: the directional gyro with a heading bug and a VOR/ILS indicator.

Where is the RNAV on a HSI?

RNAV. The legend "RNAV" will appear in the lower right corner of the instrument face when the HSI is part of an area navigation system and that mode is engaged. Slaving Meter. A slaving meter is located in the upper right hand corner of the instrument face on slaved models.

What is HSI on F-15E?

The HSI provides a basic horizontal view of the aircraft's navigation picture. In the F-15E, it can provide navigation data to selected ground navigation facilities (TACAN or Instrument Landing System (ILS)) or to onboard navigation systems like the Inertial Navigation System (INS). Instrument flying without an HSI requires a fair amount ...

How does a compass card work?

The card is mechanically coupled to the compass card set knob and, at the start of each flight, must be set by the pilot to agree with the magnetic compass heading. As the flight progresses and headings change, the directional gyro rotates the card to indicate the current heading.

What happens when the heading changes on an aircraft?

As the aircraft's heading changes, the bug rotates with the compass card, thu s alerting the pilot to the difference between the selected heading (located under the bug) and the actual aircraft heading. The heading bug may also be coupled to an autopilot or flight director system.

Can you fly without an Hsi?

Instrument flying without an HSI requires a fair amount of mental gymnastics; for this reason, the HSI is becoming more prevalent in general aviation since it provides an excellent picture for precise navigation. The HSI may display bearing and distance to a navigation aid, magnetic heading, track/ track deviation and course/course deviation.

How does CDI work?

The CDI works with the ambiguity indicator, while both are determined by the received radial and the OBS setting. You’re still east of the station with 090 in the OBS and a “From” indication. If you drift southward, the CDI will move to the left.

What is a localizer signal?

The localizer signal actually radiates directly out from the antenna in opposite directions, as if the lighthouse is actually bipolar, with a front beam and a back beam.

Can you reverse sensing a navigation indicator?

It’s actually just your senses that have to be reversed to correct properly. You can decide if that’s reverse sensing or not. Of course, this is all true if you’re using a conventional navigation indicator. If you’ve got an HSI, well, you never have to fly away from the needle.

Can you fly away from the needle with an Hsi?

If you’ ve got an HSI, well, you never have to fly away from the needle. We’ll talk about that next time. Frank Bowlin was about to risk the ire of that seasoned ATP who was headed into a mountain. Just then, though, the controller interjected vectors to save Frank’s butt—and career.

SixPapaCharlie May the force be with you

My brain is fried... The answer is 11 but I am not sure why at this moment in time.

Clark1961 Touchdown! Greaser!

See my post about how I got the Aspen HSI to show reverse sensing with the SL-30 but not the 430w.

Grum.Man En-Route

To my understanding you are on the back course of an ILS and will get reverse sensing. ILS doesn't act like a VOR.

Kritchlow Final Approach

Yup... Direction of the pointer only matters when it's a localizer. It has not bearing other than personal reference for VORs.

MauleSkinner Touchdown! Greaser!

The heading is 270...the CDI says you are on the shaded side of the localizer. That's numbers 7 & 11, and 11 is the only answer that matches, so ...apparently the HSI has not been set to an appropriate course.

Kritchlow Final Approach

There is several correct numbers, but when you look at the possible answers there H's only one that is off course... makes it easy.

Grum.Man En-Route

4, 7, and 11 are the only ones with a heading of 270°. So that narrows it down quickly, obviously it's not 4 since the needle isn't centered. 7 isn't correct because the needle is pointed away from the localizer which would put your airplane on the other side of the bar.

Remember Ndbs?

  • Perhaps you once learned to fly an NDB approach. (If not, it’s okay. I won’t hold it against you. Bear with me as we explore a little instrument-flying history.) The venerable and once-ubiquitous King KR-86—when it worked—provided an ADF bearing pointer on a user-adjustable compass card. Th…
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What’s An HSI?

  • The horizontal situation indicator is a rather busy instrument, displaying lots of useful information. For our purposes, just as an RMI combines a bearing pointer with a heading indicator, let’s think of the HSI as a single instrument that combines a gyro heading indicator with a VOR/LOC navigation instrument. Let’s look at one of many reasons that depiction is meaningful. As we explored last …
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Fly The Approach

  • Say we’re coming from the south and we’re on the localizer south course, headed north. We’ll pass MANZA then make the procedure turn, then head back in on final. Let’s say there’s a stiff wind from the west and we’re not very good at making those wind corrections, so we’re east of course. Remember, I said that the reasoning behind Rule #1 would become evident? Watch. As we set u…
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Pretty Simple, Eh?

  • Now you can see that if you rigorously follow Rule #1 with an HSI, Rule #2 is still true, but we can pretty much ignore it and can absolutely ignore Rule #3. Having followed Rule #1, all we have to do is chase the needle. On AIS charts it still takes a little mental energy to determine exactly what the inbound front course is. But, if you remember Rule #2, it’s easy. Just orient yourself on the c…
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