HORIZONTAL SITUATION INDICATOR [HSI]

Transcription

1 J. ' ~l l HORIZONTAL SITUATION INDICATOR [HSI] 1 l ~ 2 <i?ot* l TICHNICAL TRAINING SQUADRON 443tl MILITARY AIRLIFT WING, TNG (MAC) ALTUS AIR FORCE BASE, OKLAHOMA

2 l FOR TRAINING PURPOSES ONLY NOT NECESSARILY CURRENT AFTER DISTRIBUTION. I

3 Page A C-141 HORIZONTAL SITUATION INDICATOR (HSI) OBJECTIVES When you have completed the program, you should be able to: 1. List the navigation information displayed by the HSI. 2. Identify the Indicators and Warning Flags on the HSI. 3. Identify the five operating modes for the HSI. TURN to Page 1 and begin the program. Air Force OC, 23 Sep

4 Page 1 HORIZONTAL SITUATION INDICATOR The Horizontal Situation Indicator (HSI) is an integrated navigation instrument. It combines the functions of a master compass repeater, an ID-249 (except for the glideslope portion), a range indicator, and a bearing pointer. Two Horizontal Situation Indicators (HS!s) are located on the main instrument panel. d~lrrjid / I I I \ / I I,, ' / I \\ I \ '-. / I I //., '-,,, I \\ 11 \ ' // I I I I \ ', // I I'. I I ' ',,--... ' ''?Jl' '33,,.. " o. ~~ ;z;..,,, COUUf '' u1fs... 'l.~~ :: O>.: --=~"" ~.s> ' ~,-' Q, '.,., r;, I ~_,_,., o \.:.:./ 'I, I ' \..:) The pilot's and copilot's Horizontal Situation Indicators (HSis) are completely independent in operation; each using inputs from different navigation and compass systems. The Horizontal Situation Indicator (HSI) is designed to display the following navigation information: Deviation, and TO- FROM. TURN to Page 2. Heading, Bearing, Distance, Course

5 From Page 1 Page 2 To properly discuss and interpret the information displayed on the HSI, we must be able to identify the various HSI indicators. The first indicators we will be concerned with are the Aircraft Symbol and the Lubber Lines. The Aircraft Symbol and the Lubber Lines (upper and lower) are fixed under the gl ass face of the HSI and do not move. The Aircraft Symbol is considered as the actual aircraft viewed from above. The Lubber Lines serve as extensions of the aircraft nose and tail. Could we then say that the Aircraft Symbol and Upper Lubber Line represent actual aircraft heading? ( ) YES. ( ) NO. TURN to Page 4. TURN to Page 3.

6 From Page 2 Page 3 You say that the Aircraft Symbol and Upper Lubber Line does NOT represent actual aircraft heading. Why not? We always read aircraft heading relative to the nose of the aircraft. TURN to Page 4.

7 From Page 2 or 3 Page 4 YES. The Aircraft Symbol and Upper Lubber Line do represent aircraft heading. Navigational information is displayed by indicators arranged around the Aircraft Symbol. Aircraft HEADING, COURSE, BEARING, DEVIATION, and AMBIGUITY (TO-FROM) are determined by comparing the positions of the indicators relative to the Aircraft Symbol. k I! Does the HSI present a pictorial view of the navigation situation relative to the Aircraft Symbol and Lubber Lines? ( ) YES. TURN to Page 5. ( ) NO. TURN to Page 6.

8 From Page 4, 6, 8, or 9 Page 5 Okay. The HSI DOES present a pictorial v i ew of the navi gation situation relative to the Aircraft Symbol and Lubber Lines. This fact will become more apparent as we discuss the other indicators and their functions. We stated that the HSI functions as a master repeater for the compass system. To do this, we must have a Compass Card. The Compass Card continuously displays aircraft magnetic heading, and rotates as the aircraft heading changes. What is the MAG heading in the HSI below? NORTH TURN to Pa ge 9. TURN to Page 7. TURN to Page 8.,

9 From Page 4 Page 6 Why Not? The HSI DOES present a pictorial view of the navigation situation relative to the Aircraft Symbol and Lubber Lines... Remember, the Aircraft Symbol is considered to be the actual aircraft as viewed from above. TURN to Page 5. k I,

10 From Page 5 Page is correct of course. We really would be surprised if anyone chose any other answer. Aircraft heading is always read under the Upper Lubber Line. The pilot's and copilot's HSis are completely independent, each COMPASS CARD receives heading information from its respective COMPASS SYSTEM. The pilot's HSI receives magnetic heading information from the COMPASS. SYSTEM No. 1, and the copilot's from the COMPASS SYSTEM No. 2. COMPASS NO. 1 COMPASS NO. 2 PILOT'S HSI COPILOT ' S HSI TURN to Page 10.

11 From Page 5 Page 8 We'll never find the New World this way! ActuaZ aircraft heading is az~ays read under the Upper Lubber Line. GO BACK to Page 5 and look again

12 From Page 5 Page 9 You say we are flying North? Wrong! Actual aircraft heading is always read under the ~pper Lubber Line. READ Page 5 and try again.,

13 From Page 7 Page 10 Each HSI includes a Power OFF Flag on the right side of the instrument. -A When in view, the Power OFF Flag indicates low voltage or a malfunction in the Compass System associated with that instrument. Based on your past experience with other remote instruments, could you also say that the Power Off Flag could indicate l ow voltage within the HSI? ( ) YES. ( ) NO. TURN to Page 12. TURN to Page 11.

14 From Page 10 Page 11 Sorry, your selection is wrong. The HSI IS a remote instrument. Therefore, it must contain an amplifier (servo). The amplifier boosts the voltage of the heading signal to the level required to position the compass card correctly. If the amplifier fails or is affected by low voltage, the card could not be positioned to give valid heading information and the Power OFF Flag would appear. TURN to Page 12.

15 From Page 10 Page 12. Yes is the correct answer. The Power OFF Flag indicates low voltage or a malfunction in EITHER the compass system or the HSI amplifier Marker. Another indicator associated with heading information i s the Heading The Heading Marker displays the selected heading. Any heading can be manually selected by positioning the Headi ng Marker relative to the compass card. Once the Heading Marker is positioned to the selected heading, it will rotate with the compass card. Position the Heading Marker by drawing a selected heading of 150. TURN to Page 13.

16 From Page 12, 14 or 15 Page 13 You placed your Heading Marker just like this, didn ' t you? When the aircraft turns to the selected heading, the Heading Marker will then be under: ( ) the Lower Lubber Line. TURN to Page 14. ( ) the Upper Lubber Line. TURN to Page 16. ( ) either Lubber Line. TURN to Page 15.

17 From Page 13 Page 14 NO. The Lower Lubber Line is an extension of the TAIL of the Aircraft Symbol, and would display the reciprocal of the aircraft heading, not the selected heading. GO BACK to Page 13 and select another answer.

18 From Page 13 Page 15 You chose under either Lubber Line? Nope. The Lower Lubber Line is an extension of the TAIL of the Aircraft Symbol and displays the reciprocal of the aircraft heading. GO BACK to Page 13 and select another answer

19 From Page 13 Page 16 Correct! When the aircraft turns to the selected heading, the Heading Marker will be under the Upper Lubber Line. To f l y a selected heading, turn the aircraft until the Heading Marker is under the Upper Lubber Line. The selected heading is now t he actual aircraft heading. Now that we know what the Heading Marker is and what i t does, let's see how we position it. The Heading Marker is positioned by turning the Heading Set Knob. The Heading Set Knob manually positions the Heading Marker relative to the compass card for a selected heading. TURN to Page 17.

20 From Page 16 Page 17 You're doing fine so far. Let's review the information already covered. 1. The extensions of the Aircraft Symbol are called 2. Air craft magnetic heading is continuous ly displayed on the under the Upper Lubber Line. 3. The Aircraft Symbol is considered to be the as viewed from A malfunction in the compass system or HSI amplifier is indicated by the Flag. 5. The Heading Marker is manually positioned by rotating the Knob. Write in the name of each portion of the HSI associated with heading information. TURN to Page 18.

21 From Page 17 fr Page 18 Okay, now let's see how you did. 1. The extensions of the Aircraft Symbol are called Lubber Lines Aircraft magnetic heading is continuously displayed on the compass card under the Upper Lubber Line. 3. The Aircr aft Symbol is considered to be the actual aircraft as viewed from above. 4. A malfunction in the compass system or HSI amplifier is indicated Power Qff_ Warning Flag. 5. The Heading Marker is manually positioned by rotating the Heading Set Knob. Write in the name of each portion of the HSI associated with heading information. Upper Lubber Line Heading Marker Compass Card Aircraft Symbol.... Heading Set Knob Lower Lubber Line You did real good. Right? TURN to Page 19.

22 From Page 18 Page ly Our next target is the HSI Course Section. The Course Section consists of the Course Selector Window, Course Set Knob and Course Deviation Section. The Course Deviation Section includes a: Course Arrow Head and Tail Course Dev iation Indicator And Deviation Scale (.... ) Course warning Flag And TO-FROM Indicator Based on the pictures above and your past experience, would you say that the Course Arrow Head indicates the sel ected course/radial? ( ) YES. TURN to Page 21. ( ) NO. TURN to Page 20.

23 From Page 19 Page 20 Sorry, pardner; the Course Arrow Head does indicate the selected course/radial. To see how and why TURN to Page 21.

24 The Course Arrow Head does indicate the selected course/radial. Page 21 The Course Arrow Head is positioned to the desired course/radial relative to the compass card. Once positioned, the Course Arrow Head remains fixed to the course/ radial selected and will rotate with the Compass Card as the aircr aft heading changes.... Complete the following: With the Course Arrow Head positioned to a selected nav i gational course, t he Course Arrow Tail will indicate the of the sel ected course. TURN to Page 22.

25 From Page 21 or 23 Page 22 You did say RECI PROCAL, didn't you? Sure, the Course Arrow Tail indicates the reciprocal of the selected course. When the course arrow is positioned for a selected course, we are also positioning the di gital count ers in the Course Selector Window. Does the Course Selector Window provide a digital readout of the COURSE ARROW HEAD position? ( ) YES. ( ) NO. TURN to Page 24. TURN to Page 23.

26 From Page 22 Page 23 NOi You may have misread the statement. GO BACK and read Page 22 again.

27 From Page 22, 25 or 27 Page 24 Yes! The Course Selector Window does provide a digital readout of the COURSE ARROW HEAD position. The COURSE ARROW HEAD and its digital readout in the Course Selector Window is positioned by the: ( ) Heading Set Knob. ( ) Course Set Knob. ( ) Index Set Knob. TURN to.page 25. TURN to Page 26. TURN to Page 27.

28 From Page 24 Page 25 Your selection, Heading Set Knob, is incorrect. You may have confused the Heading Set Knob with the Course Set Knob. READ the question on Page 24 and try again.

29 From Page 24 Page 26 Right, the Course Set Knob mechanically positions the Course Arr ow Head and the digital counters in the Course Window to the desired course/radial. Should the digital readout in the Course Selector Window always agree with the course selected on the Course Arrow Head? ( ) YES. ( ) NO. TURN to Page 29. TURN to Page 28.

30 From Page 24 Page 27 Your selection, Index Set Knob, is wrong. You were thinking, maybe of t he BDHI? GO BACK to Page 24 and try again.

31 From Page 26 Page 28 NO. Possibly the implication of the words "meahaniaazzy positions" didn't strike home. The Course Selector Window provides a digital readout of the course selected on the Course Arrow Head, and SHOULD agree, since they are mechanically geared. Now, GO TO Page 29 and continue.

32 From Page 26 Page 29 YES is correct! The digital readout in the Course Selector Window should agree with Course Arrow Head. Anytime they do not, the HSI is malfunctioning. Now let's discuss another portion of the course deviation section, the Course Deviation Indicator. Complete the following sentence: The function of the Course Deviation Indicator is to display aircraft TURN to Page 30.

33 From Page 29 Page 30 deviation. If this was not your answer, GO BACK to Page 29 and make the correcti on. Deviation, just what the name implies; the Course Deviation Indicator (CDI) displays Aircraft Deviation (Displacement) from the desired course. i ~-::::;:;:_..._...::!. ( -~ I I... '\. \ 1. ((. _ l -. ~)\ :' ; _ 01_ LEFT OF COURSE RIGHT OF COURSE ON COURSE By comparing visually the position of the CDI relative to the Aircraft Symbol, we can see whether we are left or right of the course selected or on course. TURN to Page 31.

34 Fr om Page 30 Page 31 In the picture above, the Course Deviation Indicator (CDI) indicates. the aircraft is : ( ) left of the desired course. ( ) right of the desired course. TURN to Page 32. TURN to Page 33.

35 From Page 31 Page 32 Left of course? No. When the Course Deviation Indicator (CDI) is to the left of the Air craft Symbol, this means the aircraft is to the right of desired course. TURN to Page 33.

36 From Page 31 or 32 Page 33 Right of course is correct. When the Course Deviation Indicator (CDI) is to the l eft of the Aircraft Symbol, this means the aircraft is to the right of the desired course. Always fly toward the CDI to correct for course deviation. So that we may know the amount of deviation from course, a Course Deviation Scale has been added. This scale consists of 4 dots (... ) painted on the course plate. Each dot indicates a certain number of degrees or nautical miles of course deviation, depending on t he navigation aid selected. The amount of deviation will be discussed later with the operating modes. For the next indicator in t he HSI course section, TURN to Page 34.

37 From Page 33 Page 34 The next indicator to be discussed is the TO-FROM indicator. r The TO- FROM indicator is a triangular-shaped pointer. When the indicator points t o the Head of the Course Arrow, it indicates that the course selected, if intercepted and flown, will take the aircraft to the selected VOR or TACAN station. course : The indicator above indicates the aircraft is flying on the selected ( ) towards the selected VOR or TACAN station. ( ) from the selected VOR or TACAN station. TURN to Page 35. TURN to Page 36.

38 From Page 34 Page 35 Wrong way, Corrigan. We stated the TO-FROM indicator points to the Head of the Course Arrow when the aircraft is flying on the selected course TOWARDS the selected station. The picture showed the indicator pointing to the Tail of the Course Arrow. This means the aircraft is flying on the selected course FROM the selected station. Now TURN to Page 36.

39 From Page 34 or 35 Page 36 You are right on course going FROM the station. When the TO-FROM indicator points towards the Tail of the Course Arrow, it means the aircraft is flying on the selected course FROM the station. Now for the last indicator in the course section of the HSI, the Course Warning Flag. Based on your past experience with similiar instruments, could you say that when the Course Warning Flag is displayed, the course information is unreliable? ( ) YES. ( ) NO. TURN to Page 37. TURN to Page 41...

40 From Page 36 or 41 Page 37 Yes! When the Course Warning Flag is displayed, it indicates the course information is unreliable. ~,. As a review of the course section of the HSI, write in the name of each portion. To check your answers TURN to Page 38.

41 From Page 37 Page 38 Course Arrow Head Course Warning Flag Course Se lector Window Course Deviation Dots TO-FROM Indicator Course Arrow Tail Course Set Knob Course Deviation Ind i cator Got them all right? Fine. TURN to Page 39 and continue the review.

42 From Page 38 Page The Course Arrow Bead indicates the selected ~~~~~~~~~ 2. Does the Course Selector Window provide a digital readout of the Course Arrow Bead position? a. YES. b. NO 3. The function of the Course Deviation Indicator is to display aircraft 4. The TO-FROM Indicator indicates whether the aircraft is flying on a selected course towards or from a or ~~~~~~- -~~~~~~~station. 5. Will the Course Warning Flag be displayed if the course information is unreliable? a. YES. b. NO. TURN to Page 40 and check your answers 0

43 From Page 39 Page 40 Answers to Review Questions: 1. course or radial. 2. a. YES. 3. deviation. 4. VOR or TACAN. 5. a. YES. Check your answers on Page 39. Make any corrections necessary, then TURN to Page 42.

44 From Page 36 Page 41 Sorry about that. When the Course Warning Flag is displayed, it does indicate the course information is UNRELIABLE. TURN BACK to Page 37. t

45 From Page 40 Page 42 The last three indicators on the HSI are the Bearing Pointer, Range Indicator, and Warning Flag. First, the Bearing Pointer on the HSI operates the same as and displays the same information as similiar instruments. Based on your experience with similiar instruments, could we say that the Bearing Pointer on the HSI indicates the magnetic bearing from the aircraft to the selected ground station? ( ) YES. ( ) NO. TURN to Page 43. TURN to Page 44.

46 From Page 42 or 44 Page 43 Yes. The Bearing Pointer on the HSI does indicate the magnetic bearing from the aircraft to the selected ground station. Second, the Bearing Pointer indicates t rack angle er ror when operating in either the Navigation or Doppler Computer Modes.:_ J The last indicators ar e the Range Indicator and Warning Flag. The Range Indicator will be covered by its Warning Flag when not in use. The Range Indicator is used in three operating modes. These modes are: 1. TACAN. 2. Navigation Computer (ASN-24)..c.. 3. Doppler Computer (ASN-35). If the VOR mode has been selected, will the Warning Flag cover the Range Indicator? ( ) YES. TURN to Page 46. ( ) NO. TURN to Page 45.

47 From P.age 42 Page 44 Sorry -about that, but the Bearing Pointer on the HSI does indicate the magnetic bearing from the airc raft to the selected ground station. TURN BACK to Page 43. 0

48 From Page 43 Your answer No? Remember, the Range Indicator is used in thpee Page 45 opepating modes. These modes are: TACAN. 2. Navi gation Computer (ASN-24). 3. Doppler Computer (ASN-35). Therefore, when using the VOR mode, the Warning Fl ag will cover the Range Indicator. Now that we know... TURN to Page 46. 0

49 From Page 43 or 45 Page 46 Yes. The Warning Flag will cover the Range Indicator if the VOR mode is selected. When operating in the TACAN mode, the range information is reliable up to a range of 195 nautical miles. When operating in the Computer modes, the range information is reliable up to a range of 999 nautical miles. Now that we have identified the indicators on the HSI, to find out when they are used, TURN to Page 47.

50 From Page 46 Page 47 The TO-FROM Indicator is used only in the VOR and TACAN modes. The RANGE Indicator is used jn the TACAN.., Navi gation Computer (ASN- 24) or Doppler Computer (ASN- 35) modes. Which mode is depicted in the picture below? 1. VOR. 2. TACAN. 3. Navi gation Computers. TURN to Page 48. TURN to Page 49. TURN to Page 50.

51 From Page 47 Page 48 VOR? Well, t he TO-FROM Indicator is displayed and is used only in the VOR and TACAN modes. However, notice in the picture, a range is displayed on the Range Indicator and the Range Indicator is NOT used in VOR. Range Indicator Which mode is depicted above? ( ) TACAN. ( ) Navigation Computers. TURN to Page 49. TURN to Page

52 From Page 47, 49 or 50 Page 49 TACAN. Right. The TO-FROM Indicator was displayed and a range was displayed in the Range Indicator. This indicates the TACAN mode was dipicted. The TACAN mode is the only mode using BOTH of these indicators. - Which mode is depicted in the picture below? ( ) Navigation Computers. TURN to Page 51. ( ) VOR. TURN to Page 52.

53 From Page 47 or 48 Page 50 Navigation Computers? NOPE - -- the TO-FROM Indicator was displayed and this indicator is used only in the VOR and TACAN modes. There was also a range displayed on the Range Indicator. The Range Indicator i s used in the TACAN mode but NOT the VOR mode. For the correct answer, TURN BACK to Page 49.

54 From Page 49 Page 51 NO --- the TO-FROM Indicator was displayed and the Range Indicator was covered. These indications tell us that the VOR mode was depicted. TURN to Page 52.

55 From Page 49 or 51 Page 52 SURE. The VOR mode was depicted. ~ :::::>=w This is the only mode that will have the TO-FROM Indicator displayed and the Range Indica t or covered. Recalling that the Range Indicator is used in the TACAN or Navigation Computer modes, which mode is depic ted below? ( ) TACAN. TURN to Page 53. ( ) Navigation Computer. TURN to Page 54.

56 From Page 52 Page 53 Oops! You missed a point somehow. The TO-FROM Indicator was NOT displayed, so it could NOT have been TACAN. A range displayed on the Range Indicator but no TO-FROM Indicator tells e us one of the Navigation Computer modes has been selected. Right? TURN to Page 54

57 From Page 52 or 53 Page 54 ' Right. A range displayed on the Range Indicator hut no TO-FRQN Indicator -tells us one of the Navigation Computer modes has been selected. J The next operating mode is ILS. The ILS mode displays course deviation information but no TO-FROM, RANGE or BEARING information., Does the picture above depict the ILS mode? ( ) YES. TURN to Page 55. ( ) NO. TURN t o Page 56.

58 From Page 54 or 56 Page 55 Yes. The picture does depict the ILS mode. The ILS mode displays course deviation information but no TO-FROM, RANGE or BEARING information. ' The l ast operating mode is the NAV OFF mode. In the NAV OFF mode, the COURSE ARROW is slaved to the UPPER LUBBER LINE, the BEARING POINTER is slaved to the LOWER LUBBER LINE, the COURSE WARNING FLAG is displayed and the CDI is centered. Does the picture above depict the NAV OFF mode? ( ( ) ) YES. TURN to Page 58. NO. TURN to Page 57.

59 1 From Page 54 Page 56 NO --- you don't really believe this do you? We stated that the!ls mode displays course deviation information but no TO-FROM or RANGE infor- mation. The picture does depict the!ls mode. TURN BACK to Page 55.

60 From Page 55 Page 57 Sorry Pardner, but the picture does depict the NAV OFF mode. The COURSE ARROW was slaved to the UPPER LUBBER LINE, the BEARING POINTER was slaved to the LOWER LUBBER LINE and the COURSE WARNING FLAG was displayed. Also, the Course Deviation Indicator was centered, the Range Indicator was covered and no TO- FROM information was displayed. Now TURN to Page 58.

61 From Page 55 or 57 Page 58 Yes. The pictures does depict the NAV OFF mode. In the NAV OFF mode, the Course Arrow is slaved to the Upper Lubber Line, the Bearing Pointer is ' slaved to the Lower Lubber Line, and the Course Warning Flag is displayed. Also, the Course Deviation Indicator is centered, the Range Indicator is covered and no TO-FROM information is displayed. This completes the five operating modes, so for a review, please TURN to Page 59

62 From Page 58 Page 59 Fill in the name of each operating mode illustrated below. ' t To check your answers, TURN to Page 60.

63 * From Page 59 Page 60 ' TA CAN VOR NAVIGATION COMPUTER ILS NAV OFF Check your answers and make any necessary corrections, then TURN to Page 61.

64 From Page 60 Page 61 This completes the HSI program. If would like to review any portion, the subject pages are as follows: SUBJECT I, PAGE I' Heading S~ction 2-18 Course Section Range Indicator and Bearing Pointer Identifying Operating Modes 47-60