Horizontal Situation Indicator Explained | HSI Test Questions | How an HSI Works | Chase the Needle

Have you ever had a Horizontal Situation Indicator explained to you? The HSI test questions in the FAA IFR Knowledge Exam are some of the toughest you'll see. If you take just a little bit of time to learn how an HSI works, it will make these questions a breeze!
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The HSI combines two instruments, the directional gyro, and VOR receiver. This is great since it reduces the number of things you need to look at in your instrument scan, but since not a lot of us get much practice with an HSI in our training, can steepen the learning curve a bit. But remember that like a VOR, you can still chase the needle to navigate, and you can still use the heading function the same as you would a directional gyro, so it's not too much different.
We'll see in this video that with practice, the HSI can become intuitive and make your instrument flying a lot easier. And yes, we'll have you nailing those tricky test questions too!
Note: The needles on this HSI show up yellowish, but we still refer to these as the "green needles" since they are linked to a VOR signal, as opposed to the pink or magenta needles which would display if the instrument were paired with a GPS signal. Hope this clarifies confusion!
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/ @flightinsight9111
0:00 What is an HSI?
00:34 Using HSI as a directional gyro
0:56 Using HSI as a VOR
4:00 Test Questions: Position relative to station
6:55 Using HSI on an ILS approach
8:07 Test Questions: Position relative to localizer/backcourse

[@travishibbard4705]

Call me crazy, but I’m pretty sure that his needle is yellow. Love these videos as I’m close to getting my IR!

[@nelmijouicagalitan7979]

I also think I'm colorblind

[@sambrose1]

Then I too am crazy.

[@jimmymc10021]

It looks yellow to me and I pass my colour blindness test every year as part of my CASA licence.

[@sambrose1]

@@jimmymc10021 Is it green in the actual instrument?

[@jimmymc10021]

@@sambrose1 I fly an EFIS display on the EC145 so I can't comment on the older gauges but I do remember them being yellow and the bug being RED/ORANGE.

[@rjhornsby]

Steam gauges might seem quaint in the era of glass cockpits, but their design is still mind-blowingly genius.

[@BobbyChastain]

Well, I’m glad I’m not the only one that finds those HSI questions difficult. This video sure helped though.

[@electricitymachine6401]

You have the best educational aviation content on KZbin! Every single question I've had about instrument flying has been answered, thank you so much.

[@flightinsight9111]

Wow thanks for the kind words!

[@alangarrett1181]

I will second that! Best instructional videos on the net.

[@hotprop92]

Quick way to tell which quadrant you're in. Visualize the VOR as if it was physically sitting on the center of the HSI. You are ALWAYS in the quadrant opposite the direction of the arrow and the opposite side of the deviation bar, ALWAYS. If you get disoriented it gets you immediately in the ballpark. I love HSI's

[@tondog54]

This is so much easier, and more to the point of why the HSI is so useful for situational awareness

[@tangotango256]

THAT ...was helpful .... I'd be circling for 20 minutes trying to get my bearing especially in a strange air space without any hope of recognizing anything ... Best to keep on course and heading and plan ahead for me

[@hotprop92]

@@tangotango256 of course you're right about staying on course but when changing headings and switching to a distant VOR an HSI gives you a visual big picture much less prone to error than the standard windshield wiper VOR especially when it's one of those days when you're trying to hold on to your lunch.

[@erictsang3]

Wow, that makes it so easy to understand. I'm glad I saw this comment! Thank you so much for sharing!

[@taitepryor3241]

Your videos always make everything so clear, thank you so much!

[@MentalAviation]

The best channel i found, watching every day and improving like a machine!! Thank you so so much!

[@oncuahmet]

I love how detailed your videos are, very sharp very clear.

[@flightinsight9111]

I appreciate that!

[@bishoppearce-killian8776]

Studying for my instrument written now - this is a lifesaver. I was so confused and never used an HSI during my PPL. Thanks my dude

[@flightinsight9111]

You're most welcome. I never used an HSI either until long after my instrument checkride. Now I love em!

[@justingrind1908]

So glad I found your channel. Like others I’m working on IR. Your videos have been great tools to reinforce things I have been fuzzy on

[@masterswitchaviation]

Oh man, I’m so subscribed. You just cleared up so much! I’m coming back to rewatch this and I’m sending the Private Pilot playlist to my buddy who’s working on his PPC.

[@Shandakel]

John King talks extremely fast through the IR Ground School. This helped clarify some things. Thanks!

[@davidwasicek8999]

I will be buying a sweatshirt for all the help this channel has done for me

[@gregagee4328]

I think I'm finally starting to wrap my old brain around this stuff and visualizing where things are supposed to be! Yippee!!

[@anahiaguirre7666]

Wow! Amazing! So impressed with the helpful, professional, and high quality work on this video. Thank you a million! You’re making better pilots! 🙂 keep it up!

[@flightinsight9111]

Thanks for watching, Anahi! Happy flying

[@Biglen747]

probably one of the most helpful videos I have found on this topic

[@toddw6716]

This is the greatest for people working on IFR. Great explanation easy to understand

[@AYoungWarthog]

Working on my Instrument now and my school has me using the Gleim Kit to learn this, which is basically just reading all the content. Trying to understand this without the visual and verbal explanation was pulling my head off. Thank you so much, this made it so easy!

[@michaelstrauss9689]

I just love your videos! Thanks you so much for sharing these. This one in particular was helping me clear up some of my confusion on the test questions.

[@craigkarchner1320]

Thank you, great instructional video, easy to understand and professionally done. Your videos were a huge help in my private and are instrumental in my instrument training.

[@colt10mmsecurity68]

The FAA written IFR tests (IFR, CFII, ATP) are stupid is confusing at times. In reality and when flying, it’s so easy to just figure out what radial you’re actually on by turning the OBS and centering the needle from the station of the selected VOR. Then just tune for the direction you need to go, either TO or FROM the station. Easy.

[@mpepi8778]

Very, very well put together. I appreciate your detailed overview of the HSI; I'd recommend that even Student Pilots watch that portion. If you don't understand the foundational concepts, you will have trouble applying the knowledge to relevant situations. Thank you!

[@hanyasvagytediszno]

This video is the best explanation on this! Thank you for having made it!

[@keremkaya6915]

Perfect! Currently studying for my radnav ATPL exam and hsi questions gave me some trouble. Watching this video completely cleared the air for me. Great explanation with quality visuals. You have no idea how much of a help it was. Thanks a lot

[@flightinsight9111]

So glad to hear it. Good luck on the exam!

[@edu6582]

Amazingly done. Gr8 job Captain!!!

[@raccoonair]

It summons up all predominant elements... and more. Thanks.

[@hayleycopher8832]

This is so great. I’m getting my private and have been so confused on what all these indications mean. So helpful thank you.

[@mikesax3578]

Excellent videos. Very, very helpful. We'll done. Thank you.

[@patrickshuff]

Thank you for the incredible videos.

[@mgasalam6099]

Excellent explanation. I could visualise nicely. Thank you

[@sparkie951]

Excellent video... Just found your Channel, and will be spending a lot of time on it. thanks for sharing.

[@anatoliyvodopyanov6988]

Thanks for your work.pls continue

[@alteasanchezmartinez9914]

THIS HELPED ME A LOT THANKS !

[@dakotareistad7047]

Bravo sir, the reverse sensing was driving me crazy. I didn't know that was a thing on the localizers. Thank you!

[@bluemodem1]

Since this is day one learning HSIs for me. It would be nice if things you say are green are actually green.

[@jackhenderson9798]

Thank you so much for this video

[@jakew9887]

Great Video. Thanks

[@ethio-trapmusic7138]

great content. keep up the good work mate.

[@skyhorseprice6591]

That was _excellent!_

[@connorzach81]

this video is gold

[@Noturmoney]

your videos rock dude. thank you

[@winjarskjelten2856]

Thank you for a great explanation❤

[@muddymallow80]

So helpful! Thank you so much

[@lukecronje619]

Fantastic content. Amazing

[@rydernakoa8844]

Very informative thank you 🙏

[@psychastria]

When you're flying a localizer back course with an HSI you always set it to the FRONT COURSE radial. That eliminates the reverse sensing, and you can fly towards the needle as normal. There would be no reason to set the HSI to the back course radial. I suggest you publish a correction video that talks a little more about flying a back course with an HSI.

[@peternau1346]

I totally agree. I was shocked and disappointed that this practical technique was not mentioned, since it eliminates most of the confusion for a back course approach. OK, you need to get the test questions right and pass the test, but later, it's more important to keep things simple when you're actually flying.

[@hotprop92]

Thank you for reconfirming that for me. I haven't flown for years but I remember the back course thing with the HSI. I thought my memory was imagining things. They should redo this with a clarifying explanation. Anyway I thought I heard where the FAA is eliminating back course approaches.

[@XU23]

Yeah that’s what i thought as well

[@RandyMarsh-nu6lo]

Obviously that’s what you would do. But for testing purposes, they want to know that you know how to navigate it.

[@psychastria]

@@RandyMarsh-nu6lo Noooo...if I was taking a checkride in a plane with an HSI (which I did) and didn't set the OBS to the front course of the ILS, that would have shown that I don't know how to use the equipment in the plane. I don't know whether that alone would cause a failure on the checkride, but it would definitely be a checkmark against my proficiency. And for a written exam, questions regarding the HSI expect you to know that you have to use the front course heading.

[@breezie336]

Great video

[@eearl22]

I would find this video the night after I took my test still got an 83 though! Lol you have amazing content you got me through my instrument!

[@kyhkufa]

you saved me. thank you.

[@matthewchapman3507]

Thankfully the aircraft I will be training in has the dual Garmin G5 setup (One is the attitude indicator and the other is an HSI), so I'll be able to put this valuable knowledge to use!

[@thomaswells4976]

Good video! One minor thing to note... At 6m25s the way that we show our work is slightly confusing. The aircraft icon is turning a different direction than the HSI indicates. The little airplane graphic shows a left turn, whereas the HSI indicates you're making a right turn. It's a minor issue, but it definitely threw me off and made me rethink how the whole situation was working!

[@daapdary]

I'm late to the party, I commented about this anomaly yesterday. I should have known that others would have seen it already.🙂

[@crazypilot4017]

Nice 👍 Good stuff.

[@baliharsingh2315]

Good job

[@amedeocestini]

These contents are so av geek 😍

[@elevationtransport3753]

Thank you my dude 🤙

[@blacknass1943]

Thanks so mutch

[@ZINDJGABECORDERO]

This is good, i'd like to learn more and practice this by test questions

[@bernardanderson3758]

This one will help me on the exam

[@maheralazzawi7814]

good job

[@Hotdog6606]

So much higher quality content than fly8ma and mezeroa, etc. Thanks for your effort

[@sigbauer9782]

those other bozo's are boring and talk way too much about non-relevant things.

[@MrAlpha160]

Que video para mas perfecto, que bien explicas. Los libros de ATP deberían venir con un link a tu video.

[@joealex04041]

thanks brother

[@motlatsimolefe1077]

I will never fly but I love these videos…

[@SuperJPRF]

Great!

[@richardheinichen8279]

Good work you guys.

[@flightinsight9111]

Thanks, Richard!

[@b5a5m5]

Came up with a little memorization helper for localization/back-course feather. "Being *shady* is *not right* (left)"

[@Jacke50]

you turned to the radial ( 45 degrees ) that’s all good but you traveled to the radial and as you come closer your CDI will be alive, when are your start turning to the station and be exactly on the radial and cdi in the middle, If you start your turn when your CDI in the middle you will over shoot the radial if it is early then it will be undershoot. When exactly your start your turn.. Thank you for your videos they are very helpful 👍

[@sirjohndoeofpa3292]

Oh .. so next time I fly with Maverick, Goose, Hollywood and Iceman and we're inverted on a MiG, I will make sure to check it out and its position. Mucho Grazias

[@picopilot]

love the animations and the way map syncs with the HSI. is that a custom app or something I can download?

[@iheartaviation]

@FlightInsight Amazing content as always, probably the go-to channel for all practical facets of flying, not least IR. May I ask one question on this one please? On 6:25 we're supposed to fly to the right off-centre to intercept R270 outbound the station; your DI animation shows headings increasing as if a right turn were performed, where the airplane animation shows a turn to the left to achieve heading 315 (i.e, headings decreasing). Would it be safe to assume that the correct turn (shortest path) for this interception would be either (right or left), considering the interception heading lies exactly behind us (i.e., it is the reciprocal of current heading 135)? Vert grateful indeed for your videos and insightful channel!

[@MartyDidier]

I’m a newbie at trying to understand Flying Instruments. Would help greatly if I knew how the gage internally worked. Understand there are gyros running within the Instrument. They react and show direction on the instrument face. - How are they calibrated to a given map? - What is the directional accuracy within these systems? - Are Electronic Computer Systems more accurate then old school mechanical systems? - If I’m to trust an instrument that’s directing me, how dependable is the instrument to maintain giving an accurate instruction? - When starting my flight the instrument is probably calibrated, will it somehow or can it loose its calibration? - Would there be times during a flight I would have to scrap following the instrument and follow another directional source? Thank you for providing a great aid to understand this instrument. Sorry for the questions but I need help to understand.

[@josephstout384]

If you’re flying the backcourse, just put the inverse course. Your arrow will be pointing backwards but your CDI will deflect correctly.

[@albertbraun5214]

When flying a Loc Back Course, you always put the course selector on the front course, then fly normally (to the needle)

[@williamatkinson4371]

Why do you keep saying "green" course selector when its yellow. One of us is color blind! Anyhow, I enjoy your content and will definitely purchase your IFR course after I finish my private rating. Keep up the good work!

[@flightinsight9111]

Lol it is yellowish, but it’s the same color off an actual HSI needle, which we always call the “green needles” as opposed to the pink needles when it’s tracking a GPS course. Nope you’re good, maybe a screen issue?

[@jakew9887]

@@flightinsight9111 Thanks for the explaination as I was a little confused too.

[@vancel35]

Saying "Green" also made me do a screen capture, bring it up in my image editing tool, and it has a higher red component than green making it look yellow. #EEd147 Based on FlightInsight saying they're always called the green needles makes me think the person who got everyone to call them green was trolling everyone and now it's just an inside joke.

[@warwasp4293]

I am a computer scientist, and have no use for this information but thanks youtube

[@phillp7777]

When did HSI get started invented used so commonly on GA ac ? I don't remember them much at all 40yrs ago.. started flying for ppl in 1980... only used vor gauge.

[@michiel2047]

In practice, when flying a BC approach: could you select heading of the non-BC approoach and then follow the needle?

[@jahson3510]

Great videos thank you for posting. To anyone, @ 6:12 we were to turn right to get back on course with the out bound 270 radial so I thought the aircraft was in the top left quadrant but the aircraft turned left putting it in the bottom left. What am i not understanding please? (IFR Student)

[@moriver3857]

I've watched a few of your videos, which I find great. However, you should replace the term "chasing the needle" with a "fly-to" term instead. After an HSI, the next move up is typically a flight director, which has "fly-to" commands, therefore it makes sense to introduce the term early so it sticks. Also, when using the HSI for an ILS, it's good to remember that the CDI will be centered if you are inbound on LOC, even if the CDI is on the incorrect front course. Also, the HSI is very helpful during crossword condition as the wind correction angle will be right on front of you in plain view. To my knowledge, there are very few BC approaches in the US. Not sure why the FAA still asks on BC, as well as NDB approaches. Canada and other parts of the world are a different story. Keep up the good work.

[@Pork-Chopper]

Crossword Condition?? 🤔 That's a new aviation term for me. Also "chasing the needle" is understood because early instruments were analog. "Fly to"? Really. I mean you are already up in the air flying, right? So you are, chasing the needle on the instrument. Not "flying to" the needle. Also, on Helicopters you have engine rpm and Rotor rpm on the same instrument. When the "needles" align, both rotor and engine rpm are at the same rpm. When you "split the needles" this normally means that the sprag clutch is disengaged or the engine is now disengaged from the rotor and the rotor is free wheeling, normally used in Autorotations. IMO this "fly to" shit don't work. If it works for you, good. Let's not try to change convention here. In all the aviation books I've read the term used is needle. Like a Compass needle. Not a Compass "fly to". Most pilots would agree. Now, where are we going to fly to, today?

[@rateoneturn]

Hello, thank for the video, it's great. I believe there's been a mistake with the last example; the aircraft should be North of radial 270.

[@junitaa.9337]

Hi.. may i ask question? On the 11:47, example 3, why you put the aircraft on lower quadrant for both aircraft? Isnt the aircraft both need to be put on top quadrant, so when they turn left, they reach the localizer?

[@tyroniousyrownshoolacez2347]

I just look down and follow roads and my compass, pretty cool.

[@braininavatnow9197]

You have a compass? I just get low enough to read the signs on the road.

[@tyroniousyrownshoolacez2347]

@@braininavatnow9197 yes

[@slehar]

Simple mnemonic: on BC approaches, the needle is the airplane, bring it back to the center. Needle right, correct left.

[@gregor_man]

Very good video, I enjoyed this. But what is this simulator at 0:00?

[@stephentheriault1812]

In the instrument testing supplement FAA-CT-8080-3F regarding figure 96 shows runways 09 and 27. in the figure 09 has right shading and no marker beacons, 27 has LEFT shading AND marker beacons. So does the fact 09 has right shading mean normal sensing? Does the fact 27 has left shading mean it has reverse sensing BUT it does have marker beacons, do they cancel out the reverse sensing?? One test question refers to both figure 96 and 97 and asks to which aircraft position does HSI presentation "E" correspond? You have three options to answer, either #8, #3 or both #8 and #3. Your only options are on the shaded side of the feather however the HSI presentation "E" shows the needle off to the right whereas your rule you made mention of at 9:45 states "no matter what, if the aircraft is on the shaded side of the feather, the needle will be off to the left..." I am using ASA practice test software and apparently the correct answer is both #8 and #3, disregarding whether reverse sensing is a factor or not and selecting both solely based on the fact they have a 045 heading. Thats a lot of conflicting information. Thoughts?

[@billmoran3812]

I learned to fly IFR using a CDI and separate DG. Try flying a back course Localizer approach with that! After I got my instrument rating, I flew a King Air with an HSI. SO Much easier! Hand flying an ILS with a HSI is not hard at all.

[@apachesasquach]

@6:25 the animation for the aircraft turn is reversed from what you indicate on the hdi. You indicate a right hand turn on the hdi but the airplane turns left. Love the video btw

[@BB-zk6sl]

I caught this too, minor details but it definitely confuses things

[@jahson3510]

LOL I just posted the same question. Glad i wasn't the only one

[@lohphat]

Wouldn't the ILS localizer feather point be at the FAR end of the runway? Only the back course is from the near-end of a runway.

[@daapdary]

At 6:22, the HSI doesn't match the plane. To intercept radial 270, the plane turns left (counter-clockwise), therefore the heading actually _decreases,_ i.e. 135 down to 0 (same as 360), then 360 down to 315. However, the HSI incorrectly shows the heading _increasing_ (135 up to 315). Note the moment when the plane is heading east (parallel to radial 90), the HSI says the heading is 180. I use flight simulators casually, so I hope this is clear enough.

[@royludwig5046]

If you tune 270 on the Back Course instead of 090 shouldnt that prevent reverse sensing on the back course?

[@lahto1]

In 2nd example airplane is turning left on map but turning right on hsi,that should indicate turning to the left as well.Correct me if I am wrong

[@bobpaymayesh9444]

Do you use x plane or ms flight sim?

[@Boulderdan356]

At 6:25 you display the aircraft turning left, but the instrument shows a turn to the right. Still a 180, so it doesn't matter which way to go, but definitely tumbled my gyros a bit.

[@flightinsight9111]

Thanks so much, you're right that is disorienting! Will be fixed in the version on the full course.

[@tsmgguy]

The HSI is a little like the constant speed prop. It makes intuitive sense, the first opportunity you have to fly with one.

[@poonkinlok]

Seems like lots of people are getting their instruments tickets!

[@shreedhar333]

@5:08 In the first example, why is there no reverse sensing since the airplane is pointing away from the VOR when the instrument is set up to fly towards the VOR? Shouldn’t the airplane be in the lower left quadrant because of reverse sensing?

[@hotprop92]

That's the beauty of the HSI there's no reverse sending.

[@kurtreber9813]

HSI was the hardest part of IFR ground

[@jctaz27]

At 11:47 of this video, in your third example, you identify the airplane as being in the lower left quadrant. The arrow on the HSI is pointed to 9. the drawing on the paper shows the feathers such that this is the 27 approach. Are these in contradiction? It’s as if the HSI isn’t matched up to the intended course. My question is, did you use the HSI in this example, as if it is set up to approach a different chart (the 9 approach)? The HSI doesn’t know which piece of paper, or arrows, you’re using…. So, just according to the HSI, I’d expect that this plane is on a 31 heading. but, since the HSI is set up to go TO 09, and since the needle is to the right of center, as one goes toward 09, then isn’t the plane to the left of center, approaching 09? This puts the plane in the top left quadrant. thank you.

[@echosierraenroute]

i agree that part seems wrong, the aircraft is left of course of 09 so it would be in top left quadrant... great videos regardless.

[@junitaa.9337]

I was also think like this! I still dont get it. So which one is the right answer? I also find out the airplane need to be top-left quadrant (for rwy 9), and top right quadrant (for rwy 27)

[@venkybabu4842]

What is testing. When you see something beyond specifications called constraints. Example if a person says something can withstand a temperature of 100. You should test upto 120. So that things work within the range specified.

[@joeboisselle5109]

@5:01 It's deviated to the right, so we need to turn right. @5:18 So we chase the needle left. @6:07 Again we're to the right of center so we'll need to correct to the right. @6:24 So we need to chase the needle all the way around (Turns left) I'm sooo confused.