TC 3-04.5 (7-APR-17).pdf

TC 3-04.5 Instrument Flight for Army Aviators APRIL 2017 DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited. This publication supersedes FM 3-04.240,...

TC 3-04.5 Instrument Flight for Army Aviators APRIL 2017 DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited. This publication supersedes FM 3-04.240, dated 30 April 2007. Headquarters, Department of the Army This publication is available at the Army Publishing Directorate site (http://www.apd.army.mil), and the Central Army Registry site (https://atiam.train.army.mil/catalog/dashboard)  TC 3-04.5 Headquarters Training Circular Department of the Army No. 3-04.5 Washington, DC, 7 April 2017 Instrument Flight for Army Aviators Contents Page PREFACE............................................................................................................ xiii INTRODUCTION.................................................................................................. xv Chapter 1 FLIGHT INSTRUMENTS AND SYSTEMS........................................................ 1-1 Section I – Pitot-Static Systems...................................................................... 1-1 Altimeter.............................................................................................................. 1-2 Airspeed Indicator............................................................................................... 1-8 Digital Airspeed Indicator.................................................................................... 1-9 Vertical Speed Indicator..................................................................................... 1-9 Section II – Compass Systems..................................................................... 1-11 Magnetic Compass........................................................................................... 1-12 Compass Error................................................................................................. 1-12 Radio Magnetic Indicator.................................................................................. 1-17 Section III – Gyroscopic Systems................................................................. 1-18 Properties......................................................................................................... 1-18 Attitude Indicator............................................................................................... 1-19 Turn-and-Slip Indicator..................................................................................... 1-19 Turn Coordinator.............................................................................................. 1-20 Section IV – Flight Management System..................................................... 1-21 Horizontal Situation Indicator............................................................................ 1-22 Vertical Situation Indicator................................................................................ 1-23 Chapter 2 ROTARY-WING INSTRUMENT FLIGHT MANEUVERS.................................. 2-1 Section I – Maneuver Performance................................................................. 2-1 Control................................................................................................................ 2-1 Performance....................................................................................................... 2-2 Navigation........................................................................................................... 2-2 Procedural Steps................................................................................................ 2-2 Primary and Supporting Methods....................................................................... 2-3 Section II – Flight FUNDAMENTALS............................................................... 2-4 Cross-Check....................................................................................................... 2-4 Instrument Interpretation.................................................................................... 2-6 DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited. This publication supersedes FM 3-04.240, dated 30 April 2007. i Contents Aircraft Control.................................................................................................... 2-6 Section III – Instrument Takeoff....................................................................... 2-7 Preparing............................................................................................................. 2-7 Performing From Hover/Ground......................................................................... 2-8 Takeoff................................................................................................................ 2-8 Common Errors................................................................................................... 2-8 Section IV – Straight-and-Level Flight............................................................ 2-9 Pitch Attitude Control.......................................................................................... 2-9 Bank Control..................................................................................................... 2-10 Power Control................................................................................................... 2-11 Common Errors................................................................................................. 2-13 Section V – Straight Climbs and Descents.................................................. 2-13 Climb Entry........................................................................................................ 2-13 Climb Level-Off................................................................................................. 2-15 Descent Entry.................................................................................................... 2-15 Descent Level-Off............................................................................................. 2-15 Common Errors................................................................................................. 2-15 Section VI – Turns........................................................................................... 2-16 Predetermined Heading.................................................................................... 2-16 Timed................................................................................................................ 2-17 Changing Airspeed............................................................................................ 2-17 Compass........................................................................................................... 2-18 Climbing and Descending................................................................................. 2-19 Common Errors................................................................................................. 2-19 Section VII – Other Maneuvers...................................................................... 2-20 Unusual Attitudes.............................................................................................. 2-20 Autorotations..................................................................................................... 2-20 Chapter 3 FIXED-WING INSTUMENT FLIGHT MANEUVERS.......................................... 3-1 Section I – Instrument Takeoff......................................................................... 3-1 Takeoff................................................................................................................ 3-1 Common Takeoff Errors and Resolutions........................................................... 3-2 Section II – Straight-and-Level Flight.............................................................. 3-2 Pitch Control........................................................................................................ 3-2 Bank Control....................................................................................................... 3-6 Power Control..................................................................................................... 3-8 Trim Technique................................................................................................. 3-11 Section III – Straight Climbs and Descents.................................................. 3-12 Constant-Airspeed Climb.................................................................................. 3-12 Constant-Rate Climb......................................................................................... 3-13 Level-Off............................................................................................................ 3-14 Airspeed Descent.............................................................................................. 3-15 Level-Off............................................................................................................ 3-15 Common Climb and Descent Errors and Resolutions...................................... 3-16 Section IV – Turns........................................................................................... 3-16 Steep Turns....................................................................................................... 3-17 Climbing and Descending Turns....................................................................... 3-19 ii TC 3-04.5 7 April 2017  Contents Change of Airspeed During Turns.................................................................... 3-19 Common Turn Errors........................................................................................ 3-20 Section V – Other Maneuvers........................................................................ 3-21 Approach to Stall.............................................................................................. 3-21 Unusual Attitudes and Recoveries................................................................... 3-22 Chapter 4 AIR NAVIGATION CHARTS.............................................................................. 4-1 Section I – Air Navigation................................................................................ 4-1 Equator............................................................................................................... 4-1 Meridian.............................................................................................................. 4-1 Degrees, Minutes, and Seconds........................................................................ 4-1 Degrees and Decimal Minutes........................................................................... 4-2 Decimal Degrees................................................................................................ 4-2 Earth Circumference........................................................................................... 4-3 Distance.............................................................................................................. 4-3 Speed................................................................................................................. 4-3 Navigation Charts............................................................................................... 4-3 Weather Information and Communication Features........................................ 4-10 Departure Procedure Chart.............................................................................. 4-11 Standard Terminal Arrival Route Charts.......................................................... 4-11 Instrument Approach Procedure Chart............................................................. 4-11 Inoperative Components.................................................................................. 4-24 Section II – Plotting and Measuring.............................................................. 4-25 Plotter............................................................................................................... 4-25 Measurements and Course Lines.................................................................... 4-25 Chapter 5 AIR NAVIGATION HANDHELD COMPUTER................................................... 5-1 Section I – Calculator Side.............................................................................. 5-1 Values................................................................................................................. 5-1 Indexes............................................................................................................... 5-1 Time and Distance.............................................................................................. 5-2 Short Time and Distance (Use of the 36 Index)................................................. 5-3 Computing Time for Outbound Leg During Holding........................................... 5-4 Fuel Consumption.............................................................................................. 5-6 True Airspeed..................................................................................................... 5-8 Distance Conversion.......................................................................................... 5-9 True Altitude Calculation.................................................................................. 5-11 Multiplication and Division Calculations........................................................... 5-11 Converting Distance to Time............................................................................ 5-13 Section II – Wind Side.................................................................................... 5-13 Disk and Correction Scales.............................................................................. 5-13 Reversible Grid................................................................................................. 5-13 Determining Heading and Ground Speed........................................................ 5-14 Determining Unknown Wind............................................................................. 5-15 Determining Altitude for Most Favorable Wind................................................. 5-16 Determining Radius of Action........................................................................... 5-17 Chapter 6 INSTRUMENT WEATHER................................................................................. 6-1 Effects of Wind................................................................................................... 6-1 7 April 2017 TC 3-04.5 iii Contents Turbulence.......................................................................................................... 6-3 Structural Icing.................................................................................................... 6-4 Fog...................................................................................................................... 6-5 Volcanic Ash....................................................................................................... 6-6 Thunderstorms.................................................................................................... 6-6 Wind Shear......................................................................................................... 6-6 Chapter 7 NAVIGATION AIDS............................................................................................ 7-1 Section I – Basic Radio Principles.................................................................. 7-1 Radio Wave Propagation.................................................................................... 7-1 Surface Wave...................................................................................................... 7-1 Sky Wave............................................................................................................ 7-1 Space Wave........................................................................................................ 7-2 Radio Wave Reception Disturbances................................................................. 7-2 Precautions......................................................................................................... 7-3 Section II – Navigation Systems...................................................................... 7-3 NonDirectional Radio Beacon............................................................................. 7-3 Frequency........................................................................................................... 7-3 Automatic Direction Finder.................................................................................. 7-3 Compass Locator................................................................................................ 7-4 Voice Transmission............................................................................................. 7-4 Identification........................................................................................................ 7-4 Accuracy............................................................................................................. 7-4 Disturbances....................................................................................................... 7-5 Very High Frequency OmniDirectional Range.................................................... 7-5 Tactical Air Navigation Theory of Operation....................................................... 7-8 Very High Frequency OmniDirectional Range/Tactical Air Navigation............... 7-9 Distance Measuring Equipment.......................................................................... 7-9 Global Positioning System................................................................................ 7-10 Signal Accuracy................................................................................................ 7-10 Segments.......................................................................................................... 7-11 Navigation Database......................................................................................... 7-11 Outside United States National Airspace System............................................. 7-11 Receiver Autonomous Integrity Monitoring....................................................... 7-11 Database Requirements................................................................................... 7-11 Manual Database Manipulation........................................................................ 7-12 Embedded Global Positioning System/Inertial Navigation System.................. 7-12 Course Sensitivity............................................................................................. 7-12 Wide-Area Augmentation System..................................................................... 7-12 Local Area Augmentation System..................................................................... 7-13 Inertial Navigation System................................................................................ 7-13 Section III – Navigation Procedures.............................................................. 7-13 Tune.................................................................................................................. 7-14 Identify............................................................................................................... 7-14 Monitor Station Identification............................................................................. 7-14 Select................................................................................................................ 7-15 Set..................................................................................................................... 7-15 Monitor for Warning Flags................................................................................. 7-15 iv TC 3-04.5 7 April 2017  Contents Check................................................................................................................ 7-15 Homing to a Station.......................................................................................... 7-15 Tracking to a Station......................................................................................... 7-16 Course Intercept............................................................................................... 7-21 Arc Interceptions............................................................................................... 7-27 Area Navigation................................................................................................ 7-30 Global Positioning System Navigation............................................................. 7-33 Chapter 8 AIRSPACE......................................................................................................... 8-1 Section I – National Airspace System............................................................ 8-1 Airspace Classification....................................................................................... 8-1 Special-Use Airspace......................................................................................... 8-3 Other Airspace.................................................................................................... 8-4 Federal Airway.................................................................................................... 8-5 Section II – International Civil Aviation Organization................................... 8-7 Safety.................................................................................................................. 8-7 Applicability......................................................................................................... 8-7 Current Information and Procedures.................................................................. 8-7 Terminal Instrument Approach Procedures........................................................ 8-7 Compliance......................................................................................................... 8-7 Departure Procedures........................................................................................ 8-8 Approach Procedures....................................................................................... 8-10 Holding.............................................................................................................. 8-16 Altimeter Setting Procedures............................................................................ 8-18 Transponder Operating Procedures................................................................. 8-19 Chapter 9 AIR TRAFFIC CONTROL SYSTEM.................................................................. 9-1 Navigation/Communication Equipment.............................................................. 9-1 Radar and Transponders.................................................................................... 9-1 Procedures......................................................................................................... 9-1 Facilities.............................................................................................................. 9-2 Control Sequence............................................................................................... 9-5 Letters of Agreement.......................................................................................... 9-8 Chapter 10 INSTRUMENT FLIGHT RULES INFORMATION AND PROCEDURES......... 10-1 Section I – Sources of Flight Planning Information.................................... 10-1 Department of Defense Flight Information Publications................................... 10-1 General Planning.............................................................................................. 10-1 Area Planning................................................................................................... 10-1 Flight Information Handbook............................................................................ 10-2 Instrument Flight Rules Supplement................................................................ 10-2 Instrument Flight Rules En Route Low-Altitude Charts.................................... 10-2 Instrument Flight Rules En Route High-Altitude Charts................................... 10-2 Terminal High and Low Altitude....................................................................... 10-2 Civil Publications.............................................................................................. 10-3 Section II – Instrument Flight Rules Flight Plan.......................................... 10-4 Prior to Flight.................................................................................................... 10-4 In Flight............................................................................................................. 10-5 Canceling.......................................................................................................... 10-5 7 April 2017 TC 3-04.5 v Contents Section III – Clearances.................................................................................. 10-5 Separations....................................................................................................... 10-7 Visual Flight Rules-on-Top................................................................................ 10-7 Visual Flight Rules Over-the-Top...................................................................... 10-8 Section IV – Notice to Airmen System.......................................................... 10-8 Notice to Airmen................................................................................................ 10-8 Notices to Airmen Types................................................................................... 10-8 Internet Distribution System............................................................................ 10-10 Section V – Navigation Options in the National Airspace System.......... 10-12 On Airways...................................................................................................... 10-12 Off Airways (Direct)......................................................................................... 10-13 Section VI – Departures................................................................................ 10-13 Diverse Departure........................................................................................... 10-16 Radar Controlled Departure............................................................................ 10-16 Departure From Airports Without an Operating Control Tower...................... 10-16 Section VII – En Route.................................................................................. 10-17 Position Reports.............................................................................................. 10-17 Additional Reports........................................................................................... 10-17 Planning Descent and Approach.................................................................... 10-18 Standard Terminal Arrival Routes................................................................... 10-19 Inoperative/Unusable Components Substitution............................................. 10-21 Holding Procedures......................................................................................... 10-21 Section VIII – Approaches............................................................................ 10-26 Published Procedure Compliance................................................................... 10-26 Instrument Letdown......................................................................................... 10-26 Full Approach.................................................................................................. 10-26 Radar Vectors................................................................................................. 10-27 Without an Operating Control Tower.............................................................. 10-27 Approach Control Present............................................................................... 10-29 Low-Altitude Approaches................................................................................ 10-29 High-Altitude Approach................................................................................... 10-38 Final Approach................................................................................................ 10-40 Other Approaches........................................................................................... 10-48 Missed Approaches......................................................................................... 10-51 Section IX – Landing..................................................................................... 10-52 Land and Hold Short Operations.................................................................... 10-52 Landing Fees.................................................................................................. 10-52 Chapter 11 EMERGENCY OPERATIONS.......................................................................... 11-1 Section I – Emergencies................................................................................. 11-1 Inadvertent Thunderstorm Encounter............................................................... 11-1 Inadvertent Icing Encounter.............................................................................. 11-2 Precipitation Static............................................................................................ 11-2 Aircraft System Malfunctions............................................................................ 11-2 Two-Way Radio Failure.................................................................................... 11-3 Communication/Navigation Malfunction............................................................ 11-3 Loss of Situational Awareness.......................................................................... 11-4 vi TC 3-04.5 7 April 2017  Contents Inadvertent Instrument Meteorological Condition............................................. 11-4 Section II – Air Traffic Control Requirements and Responsibilities......... 11-5 Provide Information.......................................................................................... 11-5 Request Assistance.......................................................................................... 11-6 Responsibility................................................................................................... 11-7 Appendix A INSTRUMENT FLIGHT RULES OPERATIONS................................................ A-1 Appendix B INSTRUMENT FLIGHT IN A THEATER OF OPERATIONS............................. B-1 Appendix C WEATHER REPORTS AND RISK MANAGEMENT......................................... C-1 Appendix D INTERNET ADDRESSES AND ACCESS......................................................... D-1 GLOSSARY............................................................................................ Glossary-................................................................................................................................ 1 REFERENCES.................................................................................... References-................................................................................................................................ 1 INDEX............................................................................................................ Index-................................................................................................................................ 1 Figures Figure 1-1. Pitot-static head................................................................................................... 1-1 Figure 1-2. Altimeter components.......................................................................................... 1-2 Figure 1-3. Types of altitude................................................................................................... 1-3 Figure 1-4. Altimeter error caused by nonstandard temperature........................................... 1-4 Figure 1-5. Altimeter error caused by nonstandard atmospheric pressure............................ 1-5 Figure 1-6. Temperature correction chart (height in feet)...................................................... 1-6 Figure 1-7. Encoding altimeter with a malfunction................................................................. 1-6 Figure 1-8. UH-60M digital radar altimeter............................................................................. 1-7 Figure 1-9. UH60-M digital barometric altimeter.................................................................... 1-8 Figure 1-10. Mechanism of an airspeed indicator.................................................................. 1-8 Figure 1-11. UH-60M digital airspeed indicator...................................................................... 1-9 Figure 1-12. Vertical speed indicator.................................................................................... 1-10 Figure 1-13. Instantaneous vertical speed indicator............................................................. 1-11 Figure 1-14. UH-60M digital vertical speed indicator........................................................... 1-11 Figure 1-15. Magnetic compass........................................................................................... 1-12 Figure 1-16. Lines of magnetic variation.............................................................................. 1-13 Figure 1-17. Pilot compass correction card.......................................................................... 1-15 Figure 1-18. Turning error.................................................................................................... 1-16 Figure 1-19. Acceleration error............................................................................................. 1-16 Figure 1-20. Radio magnetic indicator................................................................................. 1-17 Figure 1-21. Precession diagram......................................................................................... 1-18 Figure 1-22. Attitude indicator.............................................................................................. 1-19 Figure 1-23. Turn indicator................................................................................................... 1-20 7 April 2017 TC 3-04.5 vii Contents Figure 1-24. UH-60M multifunction display.......................................................................... 1-21 Figure 1-25. UH-60M flight management display system.................................................... 1-22 Figure 1-26. Horizontal situation indicator........................................................................... 1-22 Figure 1-27. UH-60 vertical situation indicator..................................................................... 1-23 Figure 2-1. Control instruments (UH-60)................................................................................ 2-1 Figure 2-2. Performance instruments (UH-60)....................................................................... 2-2 Figure 2-3. Navigation instruments (UH-60).......................................................................... 2-2 Figure 2-4. Pitch control instruments..................................................................................... 2-3 Figure 2-5. Bank control instruments..................................................................................... 2-4 Figure 2-6. Cross-check pattern............................................................................................ 2-5 Figure 2-7. Instrument interpretation comparison.................................................................. 2-6 Figure 2-8. Instrument takeoff indications.............................................................................. 2-8 Figure 2-9. Straight-and-level flight at normal cruise speed................................................ 2-12 Figure 2-10. Straight-and-level flight with airspeed deceasing............................................ 2-12 Figure 2-11. Climb entry....................................................................................................... 2-13 Figure 2-12. Stabilized constant airspeed climb.................................................................. 2-14 Figure 2-13. Stabilized constant-rate climb.......................................................................... 2-14 Figure 2-14. Standard rate turn to the left............................................................................ 2-16 Figure 2-15. Compass turn correction diagram................................................................... 2-18 Figure 2-16. Stabilized left climbing turn, constant airspeed............................................... 2-19 Figure 3-1. Pitch attitude and airspeed in level flight............................................................. 3-3 Figure 3-2. Slip indication....................................................................................................... 3-7 Figure 3-3. Skid indication..................................................................................................... 3-7 Figure 3-4. Straight-and-level flight........................................................................................ 3-9 Figure 3-5. Airspeed deceasing............................................................................................. 3-9 Figure 3-6. Reduced airspeed stabilized............................................................................. 3-10 Figure 3-7. Climb entry......................................................................................................... 3-12 Figure 3-8. Stabilized constant airspeed climb.................................................................... 3-13 Figure 3-9. Stabilized constant rate climb............................................................................ 3-13 Figure 3-10. Level-off........................................................................................................... 3-14 Figure 3-11. Constant airspeed descent, airspeed high—reduce power............................ 3-15 Figure 3-12. Level-off at descent airspeed.......................................................................... 3-16 Figure 3-13. Standard rate turn............................................................................................ 3-17 Figure 3-14. Steep right turn................................................................................................ 3-18 Figure 3-15. Change of airspeed in turn.............................................................................. 3-19 Figure 3-16. Unusual attitude—nose high........................................................................... 3-22 Figure 3-17. Unusual attitude—nose low............................................................................. 3-23 Figure 4-1. Longitude and latitude......................................................................................... 4-2 Figure 4-2. En route airport legend........................................................................................ 4-5 Figure 4-3. Navigational aid and communication boxes........................................................ 4-8 Figure 4-4. Air traffic services and airspace information........................................................ 4-9 Figure 4-5. Automated flight service station......................................................................... 4-10 viii TC 3-04.5 7 April 2017  Contents Figure 4-6. Remote communications outlet.......................................................................... 4-11 Figure 4-7. Navigational aid box........................................................................................... 4-11 Figure 4-8. Instrument approach chart................................................................................. 4-13 Figure 4-9. Procedures and notes........................................................................................ 4-14 Figure 4-10. Basic T design of terminal arrival area............................................................. 4-18 Figure 4-11. Profile view features......................................................................................... 4-19 Figure 4-12. Landing minimums........................................................................................... 4-20 Figure 4-13. Point in space approach.................................................................................. 4-23 Figure 4-14. Remote altimeter settings................................................................................ 4-23 Figure 4-15. Inoperative components................................................................................... 4-24 Figure 4-16. East/west course reading, using outer/inner scale.......................................... 4-26 Figure 4-17. North course reading, using inner scale.......................................................... 4-26 Figure 4-18. Drawing a course line from a known point....................................................... 4-27 Figure 5-1. CPU-26A/P calculator side.................................................................................. 5-1 Figure 5-2. Calculator side of CPU-26A/P computer............................................................. 5-2 Figure 5-3. Computing time and distance.............................................................................. 5-3 Figure 5-4. Computing speed................................................................................................. 5-3 Figure 5-5. Short time and distance....................................................................................... 5-4 Figure 5-6. Estimated outbound time more than one minute................................................. 5-5 Figure 5-7. Estimated outbound time less than one minute................................................... 5-5 Figure 5-8. Gallons and pounds conversion........................................................................... 5-6 Figure 5-9. Computing time for fuel consumption.................................................................. 5-7 Figure 5-10. Fuel required...................................................................................................... 5-7 Figure 5-11. Rate of fuel consumption................................................................................... 5-8 Figure 5-12. True airspeed computation................................................................................ 5-9 Figure 5-13. Nautical, statute, and kilometer correlation...................................................... 5-10 Figure 5-14. Inner scale computation................................................................................... 5-10 Figure 5-15. True altitude calculation................................................................................... 5-11 Figure 5-16. Multiplication.................................................................................................... 5-12 Figure 5-17. Division............................................................................................................. 5-12 Figure 5-18. Converting feet per nautical mile to feet per minute........................................ 5-13 Figure 5-19. Wind side of CPU-26A/P computer.................................................................. 5-14 Figure 5-20. Heading and ground speed.............................................................................. 5-15 Figure 5-21. Determining unknown wind.............................................................................. 5-16 Figure 5-22. Determining altitude for most favorable wind................................................... 5-16 Figure 5-23. Determining radius of action, part I.................................................................. 5-17 Figure 5-24. Determining radius of action, part II................................................................. 5-18 Figure 5-25. Determining radius of action, part III................................................................ 5-19 Figure 6-1. Wind effect and ground speed............................................................................. 6-2 Figure 6-2. Wind drift.............................................................................................................. 6-2 Figure 6-3. Wind drift angle.................................................................................................... 6-3 Figure 6-4. Wind correction angle.......................................................................................... 6-3 7 April 2017 TC 3-04.5 ix Contents Figure 6-5. Instrument scan in severe turbulence (blurry instrument panel)......................... 6-4 Figure 6-6. Glide-slope deviations in wind shear................................................................... 6-7 Figure 7-1. Surface, space, and sky wave propagation......................................................... 7-2 Figure 7-2. Very high frequency omnidirectional range radials............................................. 7-6 Figure 7-3. Homing to a station............................................................................................ 7-16 Figure 7-4. Push the head................................................................................................... 7-17 Figure 7-5. Pull the tail......................................................................................................... 7-18 Figure 7-6. Tracking inbound............................................................................................... 7-19 Figure 7-7. Tracking outbound............................................................................................. 7-20 Figure 7-8. Inbound course intercept of less than 45 degrees............................................ 7-23 Figure 7-9. Inbound course intercept................................................................................... 7-24 Figure 7-10. Inbound course intercept of greater than 45 degrees..................................... 7-25 Figure 7-11. Outbound course intercept immediately after station passage....................... 7-26 Figure 7-12. Outbound course intercept away from station................................................. 7-27 Figure 7-13. Arc interception from a radial........................................................................... 7-28 Figure 7-14. Localizer interception from a distance measuring equipment arc................... 7-29 Figure 7-15. Flying a distance measuring equipment arc.................................................... 7-30 Figure 7-16. Area navigation computation........................................................................... 7-31 Figure 7-17. Aircraft/very high frequency omnidirectional radio range tactical air navigation aid/waypoint relationship................................................................. 7-32 Figure 8-1. Airspace classification......................................................................................... 8-2 Figure 8-2. Victor airways and charted information............................................................... 8-6 Figure 8-3. The 45-degree/180-degree procedure turn....................................................... 8-11 Figure 8-4. The 80-degree/260-degree procedure turn....................................................... 8-11 Figure 8-5. Base turn........................................................................................................... 8-12 Figure 8-6. Comparison of Federal Aviation Administration and International Civil Aviation Organization protected airspace for a procedure turn........................ 8-12 Figure 8-7. Procedure turn entry.......................................................................................... 8-13 Figure 8-8. Base turn entry.................................................................................................. 8-13 Figure 8-9. Racetrack procedure......................................................................................... 8-15 Figure 8-10. International Civil Aviation Organization holding pattern entry sectors........... 8-17 Figure 10-1. Departure procedure..................................................................................... 10-15 Figure 10-2. Standard terminal arrival route...................................................................... 10-20 Figure 10-3. Standard holding pattern—no wind............................................................... 10-21 Figure 10-4. Standard holding pattern with drift correction................................................ 10-22 Figure 10-5. Holding pattern entry procedures.................................................................. 10-24 Figure 10-6. Holding and outbound timing......................................................................... 10-25 Figure 10-7. Facilities with standard approach procedures............................................... 10-26 Figure 10-8. Approach procedure without an operating control tower............................... 10-28 Figure 10-9. Instrument approach procedure chart with maximum air traffic control facilities available............................................................................................ 10-30 Figure 10-10. Teardrop pattern.......................................................................................... 10-32 x TC 3-04.5 7 April 2017  Contents Figure 10-11. 45/180 procedure turn.................................................................................. 10-33 Figure 10-12. 80/260 procedure turn.................................................................................. 10-34 Figure 10-13. Descent at the holding fix............................................................................. 10-35 Figure 10-14. Descent on the inbound leg......................................................................... 10-35 Figure 10-15. Procedural track approach—arcing final...................................................... 10-36 Figure 10-16. Procedural track approach—teardrop turn.................................................. 10-37 Figure 10-17. High-altitude instrument approach plate...................................................... 10-38 Figure 10-18. Instrument landing system........................................................................... 10-44 Figure 10-19. Parallel and simultaneous instrument landing system approaches............. 10-49 Figure 10-20. Circling approach area radii......................................................................... 10-50 Figure 10-21. Circling approaches..................................................................................... 10-51 Figure C-1. Takeoff data........................................................................................................ C-1 Figure C-2. En route and mission data.................................................................................. C-3 Figure C-3. Aerodrome forecasts.......................................................................................... C-5 Figure C-4. Comments/remarks............................................................................................ C-6 Figure C-5. Briefing record.................................................................................................... C-6 Figure C-6. Meteorological aviation report............................................................................ C-8 Figure C-7. Terminal area forecast...................................................................................... C-16 Tables Table 2-1. Maneuver instruments........................................................................................... 2-3 Table 2-2. Compass turn computation................................................................................. 2-19 Table 4-1. Distance conversions............................................................................................ 4-3 Table 4-2. Aircraft approach categories and circling limits................................................... 4-21 Table 4-3. Runway visual range conversion table................................................................ 4-22 Table 5-1. Gallons and pounds conversion............................................................................ 5-6 Table 6-1. Temperature ranges for ice formation................................................................... 6-5 Table 7-1. Standard wind drift correction............................................................................. 7-21 Table 8-1. Aircraft category and maximum airspeed............................................................ 8-10 Table 8-2. Aircraft category and airspeed............................................................................ 8-14 Table 8-3. Airspeeds............................................................................................................ 8-17 Table 9-1. Air traffic control facilities, services, and radio call signs...................................... 9-6 Table 10-1. Air traffic control separation parameters........................................................... 10-7 Table 10-2. Attention notice groups..................................................................................... 10-9 Table 10-3. Holding altitudes and airspeeds...................................................................... 10-23 Table 10-4. Course reversal steps..................................................................................... 10-33 Table 11-1. Additional ATC information............................................................................... 11-6 Table A-1. Sample instrument flight rules planning requirements..........................................A-5 Table B-1. Initial air traffic control capabilities........................................................................B-2 Table B-2. Transition to sustained air traffic control operations.............................................B-3 Table B-3. Service capabilities and references......................................................................B-4 7 April 2017 TC 3-04.5 xi Contents Table C-1. Takeoff data block explanation............................................................................ C-1 Table C-2. En route and mission data block explanation...................................................... C-3 Table C-3. Aerodrome forecasts block explanation............................................................... C-5 Table C-4. Comments/remarks block explanation................................................................. C-6 Table C-5. Briefing record block explanation......................................................................... C-7 Table C-6. Special weather report criteria............................................................................. C-8 Table C-7. Descriptor qualifiers........................................................................................... C-11 Table C-8. Precipitation types.............................................................................................. C-11 Table C-9. Obscuration types.............................................................................................. C-12 Table C-10. Other types of weather phenomena................................................................. C-12 Table C-11. Reportable descriptions for sky cover.............................................................. C-13 Table C-12. Automated, manual, and plain language remarks........................................... C-15 Table C-13. Automated weather observation system models............................................. C-21 Table C-14. Weather briefing............................................................................................... C-24 Table C-15. Derived mission information............................................................................. C-25 Table C-16. Radar system precipitation intensity levels...................................................... C-29 Table D-1. Websites............................................................................................................... D-1 xii TC 3-04.5 7 April 2017  Preface Training Circular (TC) 3-04.5 is specifically prepared for aviators authorized to fly Army aircraft. This manual presents the fundamentals, procedures, and techniques for instrument flying and air navigation. The principal audience for TC 3-04.5 is all Army Aviators; trainers and educators throughout the Army will also use this publication. Commanders, staffs, and subordinates ensure that their decisions and actions comply with applicable United States, international, and, in some cases, host-nation laws and regulations. Commanders at all levels ensure that their Soldiers operate in accordance with the law of war and the rules of engagement. (See Field Manual [FM] 27-10.) TC 3-04.5 uses joint terms where applicable. Selected joint and Army terms and definitions appear in both the glossary and the text. Terms for which TC 3-04.5 is the proponent publication (the authority) are italicized in the text and are marked with an asterisk (*) in the glossary. Terms and definitions for which TC 3-04.5 is the proponent publication are boldfaced in the text. For other definitions shown in the text, the term is italicized and the number of the proponent publication follows the definition. TC 3-04.5 applies to the Active Army, Army National Guard/Army National Guard of the United States and United States Army Reserve unless otherwise stated. The proponent of this publication is Headquarters, United States Army Training and Doctrine Command (TRADOC). Send comments and recommendations on Department of the Army (DA) Form 2028 (Recommended Changes to Publications and Blank Forms) or automated link (http://www.apd.army.mil) to Commander, United States Army Aviation Center of Excellence (USAACE) ATTN: ATZQ-TD-D, Fort Rucker, Alabama 36362- 5263. Comments may be e-mailed to the Directorate of Training and Doctrine at [email protected]. Other doctrinal information can be found on the Internet at Army Knowledge Online (AKO). This publication has been reviewed for operations security considerations. 7 April 2017 TC 3-04.5 xiii This page intentionally left blank.  Introduction TC 3-04.5 presents fundamentals, procedures, and techniques for instrument flying that are essential to the effective conduct of military operations and creates the ability to enable commanders to make risk decisions in less than optimal weather while preserving combat power. This publication is written for Army Aircrews to develop a fundamental understanding of knowledge and skills necessary to operate in instrument meteorological conditions (IMC). TC 3-04.5 is an excellent reference for Army aircrews; however, it cannot be expected that this training circular is all inclusive or a full comprehension of the information will be obtained by simply reading the text. TC 3-04.5 facilitates adherence to Army regulation (AR) 95-1 by providing guidance and procedures for standard Army instrument flying. Aircraft flight instrumentation and mission objectives are varied, making instruction general for equipment and detailed for accomplishment of maneuvers. Guidance found in this manual is both technique and procedure oriented. Aircraft operator manuals provide the detailed instructions required for particular aircraft instrumentation or characteristics. When used with related flight directives and publications, this publication provides adequate guidance for instrument flight under most circumstances but is not a substitute for sound judgment; circumstances may require modification of prescribed procedures. Aircrew members charged with the safe operation of United States Army, Army National Guard (ARNG), or United States Army Reserve (USAR) aircraft must be knowledgeable of the guidance contained herein. This manual applies to all military, civilian, and/or contractor personnel who operate Army aircraft, and is designed as a technical reference for Army aviators who operate under instrument flight rules (IFR) in the National Airspace System (NAS) and International Civil Aviation Organization (ICAO). The Federal Aviation Administration’s (FAA) Aeronautical Information Manual (AIM) and Instrument Flying Handbook (IFH) are not regulatory; however, both provide information that reflects examples of operating techniques and procedures required in other regulations. Furthermore, the AIM and IFH contain some techniques and procedures not consistent with Army mission requirements, regulatory guidance, waivers, exemptions, and accepted techniques and procedures. These publications, however, are the accepted standard for civil aviation and reflect general techniques and procedures used by other pilots. Much of the information contained in this manual is reproduced from the AIM and IFH and adapted for Army use. If a subject is not covered in this manual or another Army regulation, personnel will follow guidance in the AIM and the IFH unless mission requirements dictate otherwise. All figures and tables that display partial or complete navigational excerpts from other publications (such as instrument approach charts, legends, and low-altitude en route charts) are provided for reference only and should not be used in planning for or the conduct of any flight This publication incorporates the following changes: Updated the instrument approach procedure chart with FAA instrument flying handbook. Updated all applicable code of federal regulations (CFRs), FAA orders, and FAA advisory circulars. Updated position reports to reflect the flight information handbook and aeronautical information manual. Updated planning descent and approach with FAA Order 7110.65V. Updated operations below minimum descent altitude with CFR, Title 14, Part 91.175 and AR 95- 1. Included new technologies such as flight management systems, control display units, and flight management computers. 7 April 2017 TC 3-04.5 xv This page intentionally left blank.  Chapter 1 Flight Instruments and Systems The efficiency and utility of Army aircraft depend largely on flight instruments and systems accurately depicting what the aircraft is doing in flight and how well its power plants and components are functioning. Important navigation instruments are the magnetic compass, slaved gyro compass system, heading indicator, airspeed indicator, and altimeter. These instruments provide information concerning direction, airspeed, and altitude. The attitude indicator allows the aviator to control the aircraft by showing the attitude of the aircraft in relation to the natural horizon. The performance of an aircraft in a given attitude and with a certain power setting is indicated by the airspeed indicator, heading indicator, altimeter, vertical speed indicator/vertical velocity indicator, and turn-and-slip indicator. Flight instruments are grouped into three systems: pitot-static, compass, and gyroscopic. SECTION I – PITOT-STATIC SYSTEMS 1-1. Most aircraft instrument panels have three basic pressure-operated instruments: the altimeter, airspeed indicator, and vertical speed indicator (VSI). All three receive the pressures that they measure from the aircraft pitot-static system. Flight instruments depend on accurate sampling of ambient atmospheric pressure to determine the height and speed of aircraft movement through the air, both horizontally and vertically. Ambient atmospheric pressure is sampled at two or more locations outside of the aircraft by the pitot-static system. 1-2. Static pressure, or still air, is measured at a flush port where air is not disturbed. On some aircraft, this air is sampled by static ports on the side of the fuselage. A pitot-static head is a combination pickup used to sample pitot and static air pressures. Other aircraft pick up the static pressure through flush ports on the side of the electrically heated pitot-static head. These ports are in locations proven by flight tests to be in undisturbed air, and they are normally paired, one on either side of the aircraft. This dual location prevents lateral movement of the aircraft from giving erroneous static pressure indications. The areas around the static ports may be heated with electric heater elements to prevent ice forming over the port and blocking the entry of static air. 1-3. Pitot pressure, or impact air pressure, is taken in through an open-end tube pointed directly into the relative wind flowing around the aircraft. The pitot tube connects to the airspeed indicator, and the static ports deliver pressure to the airspeed indicator, altimeter, and VSI (figure 1-1). Figure 1-1. Pitot-static head 7 April 2017 TC 3-04.5 1-1 Chapter 1 ALTIMETER 1-4. An altimeter is an aneroid barometer that measures the absolute pressure of ambient air and displays that absolute pressure in terms of feet or meters above a selected pressure level. The sensitive element in an altimeter is a stack of evacuated, corrugated bronze wafers (figure 1-2). The air pressure tries to compress the wafers against their natural springiness, which works to expand them. As a result, their thickness changes as air pressure changes. Figure 1-2. Altimeter components 1-5. An altimeter has an adjustable barometric scale that allows the aviator to set the reference pressure from which the altitude is measured. This scale is visible in the Kollsman window (altimeter setting window) and adjusted by a knob on the instrument. The range of the scale is from 28.00 to 31.00 inches of mercury (Hg), or 948 to 1,050 millibars. 1-6. Rotating the knob changes both the barometric scale and altimeter pointers in such a way that a change in the barometric scale of 1 inch Hg changes the pointer indication by 1,000 feet. This is the standard pressure lapse rate below 5,000 feet. When the barometric scale is adjusted to 29.92 inches Hg, or 1,013.2 millibars, the pointers indicate the pressure altitude. To display indicated altitude, adjust the barometric scale to the local altimeter setting. The instrument then indicates the height above the existing sea-level pressure. TYPES OF ALTITUDE 1-7. The five types of altitude are indicated, absolute, true, pressure, and density. Figure 1-3, page 1-3, compares pressure, true, and absolute altitudes. Indicated altitude is altitude as read on the dial with a current altimeter setting (sea-level pressure) set in the Kollsman window. Absolute altitude is the altitude above the surface or terrain where the aircraft is flying, also called above ground level (AGL). True altitude is the altitude above mean sea level (MSL). 1-2 TC 3-04.5 7 April 2017  Flight Instruments and Systems Figure 1-3. Types of altitude 1-8. Pressure altitude is the height measured above the 29.92-inches-of-mercury pressure level (standard datum plane). If the Kollsman window is set to 29.92 Hg, the hands of the dial indicate pressure altitude. This setting is called the standard altimeter setting. In the United States, the use of pressure altitudes (standard altimeter setting) begins at 18,000 feet. These altitudes are referred to as flight levels (FLs). The following are examples of conversions of altitude in feet to flight levels. Examples of Conversions to Flight Levels 18,000 feet equals FL180; 35,000 feet equals FL350. 1-9. Density altitude is the altitude for which a given air density exists in the standard atmosphere. If the barometric pressure is lower or the temperature is higher than standard, then density altitude of the field is higher than its actual elevation such as in the following example. Density altitudes can be obtained from many airfield towers or may be computed on the dead reckoning computer (central processing unit [CPU]- 26A/P). WARNING Because higher density altitude requires a greater takeoff distance and reduces aircraft performance, failure to calculate density altitude could be fatal. Example of Density Exceeding Actual Elevation For Denver, Colorado, with an elevation of 5,500 feet, at a temperature of 100º Fahrenheit (F) and a barometer reading (corrected to MSL) of 29.55 inches of mercury, density altitude is about 10,000 feet. ALTIMETER ERROR 1-10. An altimeter indicates standard changes from standard conditions; most flying, however, involves errors caused by nonstandard conditions, where the aviator must modify the indications to correct for these errors. Two types of errors are mechanical and inherent. 7 April 2017 TC 3-04.5 1-3 Chapter 1 1-11. A preflight check to determine the condition of an altimeter consists of setting the altimeter pointer to the airport elevation or actual aircraft location altitude, if known, and noting the Kollsman window setting. After obtaining the local altimeter setting, compute altimeter error as described in the following example. Example Illustrating Difference of Actual and Displayed Altitudes Set 29.95 with pointer on field elevation; the local altimeter setting is 29.98. This setting causes a difference of 30 feet between actual and displayed altitudes (29.98 – 29.95 =.03, 10 feet for every.01). 1-12. According to the FAA, if the indication is off more than 75 feet from the surveyed elevation, the instrument must be referred to a certified instrument repair station for recalibration. The appropriate operator or maintenance manual should be referenced to confirm which limit is accurate. Differences between ambient temperature and pressure will cause an erroneous indication on the altimeter. Figure 1-4 shows the way that nonstandard temperature affects an altimeter. When the aircraft is flying in air warmer than standard, the air is less dense and pressure levels are farther apart. When the aircraft is flying at an indicated altitude of 5,000 feet, the pressure level for that altitude is higher than in air at standard temperature, and the aircraft flies higher than if the air were cooler. If the air is colder than standard, air is denser and pressure levels are closer together. When the aircraft is flying at an indicated altitude of 5,000 feet, its true altitude is lower than if the air were warmer. Figure 1-4. Altimeter error caused by nonstandard temperature 1-13. Any time that the barometric pressure lapse rate differs from the standard of inches of Hg per thousand feet in lower elevations, the indicated altitude will be different from the true altitude. Figure 1-5, page 1-5, shows a helicopter at point A flying in air in which conditions are standard; the altimeter setting is 29.92 inches Hg. When the altimeter indicates 5,000 feet, the true altitude is also 5,000 feet. The helicopter flies to point B, where pressure is lower than standard, and the altimeter setting is 28.36 inches Hg; however, the aviator does not change the altimeter to this new altimeter setting. When the altimeter shows an indicated altitude of 5,000 feet, the true altitude, or height above MSL, is 3,500 feet. 1-4 TC 3-04.5 7 April 2017  Flight Instruments and Systems Figure 1-5. Altimeter error caused by nonstandard atmospheric pressure COLD-WEATHER ALTIMETER CORRECTION 1-14. Pressure altimeters are calibrated to indicate true altitude under international standard atmospheric (ISA) conditions. Any deviation from these standard conditions results in an erroneous reading on the altimeter. This error becomes important when the aviator considers obstacle clearances in temperatures lower than standard because the aircraft’s altitude is below the figure indicated by the altimeter. The error is proportional to the difference between actual and ISA temperature and the height of the aircraft above the altimeter setting source. The amount of error is about 4 feet per 1,000 feet for each degree Celsius (°C) of difference. Corrections are only made for decision altitudes/decision heights (DHs), minimum descent altitudes (MDAs), and other altitudes inside, but not including, the final approach fix (FAF). The same correction made to decision altitudes/DHs and MDAs is applied to other altitudes inside the FAF. For current cold-weather altimeter correction procedures, refer to the Flight Information Handbook (FIH), section D. An example of cold-weather altimeter correction follows figure 1-6, page 1-6. The following guidance is an example of how to accomplish the procedure found in the FIH. To ensure adequate obstacle clearance, the values in the chart in figure 1-6, page 1-6, are—  Added to the published decision altitude/DH or MDA and step-down fixes inside the FAF whenever outside air temperature is less than 0 degree C.  Added to all altitudes in the procedure in designated mountainous regions whenever outside air temperature is 0 degree C or less.  Added to all altitudes in the procedure whenever outside air temperature is –30 degrees C or less.  Added to procedure turn, intermediate approach altitude, and height above touchdown (HAT)/height above airport (HAA) when they are 3,000 feet or more above the altimeter setting source. 7 April 2017 TC 3-04.5 1-5 Chapter 1 Figure 1-6. Temperature correction chart (height in feet) Example of Cold-Weather Altimeter Correction Published MDA 1,180 feet MSL HAT 402 (feet) Temp –30ºC Correction 80 feet MDA to use: 1,180 + 80 = 1,260 feet MSL ENCODING ALTIMETER 1-15. An encoding altimeter is also known as an Air Traffic Control Radar Beacon System, identification friend or foe, Mark XII identification system, and system (AIMS) altimeter. 1-16. When the air traffic control (ATC) transponder is set to Mode C, the encoding altimeter supplies the transponder with a series of pulses identifying the flight level (in increments of 100 feet) at which the aircraft is flying. This series of pulses is transmitted to ground radar and appears on the controller’s scope as an alphanumeric display around the return for the aircraft. The transponder allows the ground controller to identify the aircraft under his or her control and determine the pressure altitude that the aircraft is flying. 1-17. A computer inside the encoding altimeter measures the pressure referenced from 29.92 inches Hg and delivers this data to the transponder. When the aviator adjusts the barometric scale to the local altimeter setting, the data sent to the transponder is not affected. Figure 1-7 shows an altimeter with a failed encoder displayed by a red blocked code off between the 8 and 9 on the altimeter. Figure 1-7. Encoding altimeter with a malfunction 1-6 TC 3-04.5 7 April 2017  Flight Instruments and Systems RADAR ALTIMETER 1-18. The radar altimeter, also known as an absolute altimeter, measures the height of the aircraft above terrain by transmitting a radio signal, either a frequency-modulated continuous-wave or a pulse to the ground, and accurately measuring the time used by the signal in traveling from the aircraft to the ground and returning. This transit time is modified with a time delay and converted inside the indicator to distance in feet. 1-19. Most absolute altimeters have a provision for setting a low/high altitude. When the aircraft reaches this height above ground, a light illuminates and/or an aural warning sounds. Aircraft with a flight management system may have a provision for setting a decision altitude/DH or a MDA; when the aircraft reaches this height, a light illuminates and/or an aural warning sounds. For example, the UH-60 vertical situation indicator has a DH advisory light that illuminates whenever the radar altimeter is operating and the altitude indicator is at or below the set altitude on the radar altimeter. See the operator’s manual for operation of the radar altimeter. A radar altimeter has three main functions:  Serves as a ground proximity warning device.  Serves as an accurate cross-check for the barometric altimeter.  Indicates absolute height above terrain. DIGITAL RADAR ALTIMETER 1-20. A digital radar altimeter commonly displayed on an aircraft’s multifunction display can display both analog and digital height above ground level indications. The analog display consist of a radar altitude dial and pointer. The digital display consist of altitude display symbology that provides a radar altitude rolling digital readout. Figure 1-8 shows an UH-60M digital radar altimeter. Figure 1-8. UH-60M digital radar altimeter DIGITAL ALTIMETER 1-21. A digital barometric altimeter commonly displayed on a multifunction display. It includes a barometric pressure setting indication, a selected barometric altitude marker and readout, and a preselected barometric altitude marker and readout. Figure 1-9, page 1-8, shows an UH-60M digital barometric altimeter. 7 April 2017 TC 3-04.5 1-7 Chapter 1 Figure 1-9. UH60-M digital barometric altimeter AIRSPEED INDICATOR 1-22. An airspeed indicator is a differential pressure gauge that measures the dynamic pressure of the air through which the aircraft is flying. Dynamic pressure is the difference in ambient static air pressure and total, or ram, pressure caused by motion of the aircraft through the air. These two pressures are taken from the pitot-static system. 1-23. The mechanism of the airspeed indicator in figure 1-10 consists of a thin, corrugated phosphor-bronze aneroid, or diaphragm, that receives its pressure from the pitot tube. The instrument case is sealed and connected to the static ports. As pitot pressure increases or static pressure decreases, the diaphragm expands. This dimensional change is measured by a rocking shaft and gears driving a pointer across the instrument dial. Most airspeed indicators are calibrated in knots, or nautical miles per hour; some instruments show statute miles per hour, and some instruments show both. Figure 1-10. Mechanism of an airspeed indicator 1-24. There are four types of airspeed. The four types are indicated, calibrated, equivalent, and true.  Indicated airspeed (IAS) is shown on the dial of the instrument, uncorrected for instrument or system errors.  Calibrated airspeed (CAS) is the speed that the aircraft is moving through the air, which is found by correcting IAS for instrument and position errors; the aircraft operator’s manual has a chart or graph to correct IAS for these errors and provide correct CAS for various aircraft configurations.  Equivalent airspeed (EAS) is CAS corrected for compression of air inside the pitot tube; EAS is the same as CAS in standard atmosphere at sea level. As airspeed and pressure altitude increase, the CAS becomes higher and a correction for compression must be subtracted from CAS. 1-8 TC 3-04.5 7 April 2017  Flight Instruments and Systems  True airspeed (TAS) is CAS corrected for nonstandard pressure and temperature; TAS and CAS are the same in standard atmosphere at sea level. Under nonstandard conditions, TAS is found by applying a correction for pressure altitude and temperature to CAS. Aircraft equipped with TAS indicators have a temperature-compensated aneroid bellows inside the instrument case. The bellows modifies the movement of the rocking shaft inside the instrument case so that the pointer shows actual TAS; the TAS indicator provides TAS and IAS. These instruments have a conventional airspeed mechanism with an added subdial visible through cutouts in the regular dial. A knob on the instrument allows rotation of the subdial and alignment of an indication of the outside air temperature with the pressure altitude being flown; this alignment causes the instrument pointer to indicate TAS on the subdial. 1-25. In addition to the four airspeeds above, aviators must also consider and calculate ground speed. Ground speed is the speed of an aircraft relative to the surface of the earth. Ground speed is TAS corrected for wind. DIGITAL AIRSPEED INDICATOR 1-26. A digital airspeed indicator commonly displayed on a multifunction display and can display both analog and digital airspeed. The analog display consists of a round dial and usually labeled in major intervals of 20 knots and minor intervals at 5 knots. The digital readout indicates the aircraft’s true airspeed at varying increments by rolling smoothly between increments. Figure 1-11 shows an UH-60M digital airspeed indicator. Figure 1-11. UH-60M digital airspeed indicator VERTICAL SPEED INDICATOR 1-27. The VSI (figure 1-12, page 1-10) is also called a vertical velocity indicator (VVI) and was formerly known as a rate-of-climb indicator. The VSI/VVI is a rate-of-pressure change instrument that indicates any deviation from a constant pressure level. 7 April 2017 TC 3-04.5 1-9 Chapter 1 Figure 1-12. Vertical speed indicator 1-28. Inside of the instrument case is an aneroid (also called a diaphragm) much like the one in an airspeed indicator. Both the inside of this aneroid and the inside of the instrument case are vented to the static system. The case is vented through a calibrated orifice that causes pressure inside the case to change more slowly than pressure inside the aneroid. As the aircraft ascends, static pressure becomes lower and pressure inside the case compresses the aneroid, moving the pointer upward—showing a climb and indicating the number of feet per minute (FPM) that the aircraft is ascending. 1-29. When the aircraft levels off and static pressure is no longer changing, pressure inside the case becomes the same as that inside the aneroid and the pointer returns to the horizontal, or zero, position. When the aircraft descends, static pressure increases and the aneroids expand, moving the pointer downward, indicating a descent. The pointer indication in a VSI lags a few seconds behind the actual change in pressure. The VSI is more sensitive than an altimeter and useful in alerting the aviator of an upward or downward trend, thereby helping maintain a constant altitude. INSTANTANEOUS VERTICAL SPEED INDICATOR 1-30. Instantaneous vertical speed indicators (IVSIs) (figure 1-13, page 1-11) differ from VSI construction by having two accelerometer-actuated air pumps that sense an upward or downward pitch of the aircraft and instantaneously creating a pressure differential. By the time that pressure caused by the pitch acceleration dissipates, the altitude pressure change is effective. 1-31. Because accelerometers are not vertically stabilized, some error is generated in turns. If a zero indication is maintained on the IVSI when the aircraft is entering a turn, some loss in altitude will be encountered. A corresponding gain in altitude results when the aircraft is recovering from a turn. The IVSI should not be used for directly controlling vertical speed when the aircraft is rapidly banking in excess of 40 degrees. The indicator is not affected once the aircraft is in a steady turn. 1-32. The fade-out of acceleration in a steady turn happens when a turn has been started and the accompanying change in normal acceleration has been completed. Fade-out occurs because the accelerator masses settle to new balance points corresponding to the normal acceleration maintained in the turn. When a 30-degree bank is being established, altitude deviation should not exceed 90 feet while the IVSI is maintained at zero. In more steeply banked turns, turn error rapidly increases with bank angle. 1-10 TC 3-04.5 7 April 2017  Flight Instruments and Systems Figure 1-13. Instantaneous vertical speed indicator DIGITAL VERTICAL SPEED INDICATOR 1-33. A digital vertical speed indicator is commonly displayed on a multifunction display and display both analog and digital vertical speed. The analog display consists of vertical speed scale, pointer, and tape. The digital vertical speed readout provides an instantaneous numeric indication of aircraft vertical speed. Figure 1-14 shows an UH-60M digital vertical speed indicator. Figure 1-14. UH-60M digital vertical speed indicator SECTION II – COMPASS SYSTEMS 1-34. The Earth is a huge magnet surrounded by a magnetic field made up of invisible lines of flux. These lines leave the surface at the magnetic north pole and reenter at the magnetic South Pole. Lines of magnetic flux have two important characteristics: any magnet free to rotate aligns with them, and an electrical current is induced into any conductor that cuts across them. Most direction indicators installed in aircraft make use of one of these two characteristics. 7 April 2017 TC 3-04.5 1-11 Chapter 1 MAGNETIC COMPASS 1-35. A magnet is a piece of material, usually a metal containing iron, which attracts and holds lines of magnetic flux. Every magnet, regardless of size, has two poles: north and south. When one magnet is placed in the field of another, the unlike poles attract each other and like poles repel. 1-36. The magnetic compass (figure 1-15) is one of the oldest, simplest, and most basic instruments. AR 95- 1 requires a magnetic compass for all flights. The compass bowl is the interior portion of the compass card that supports the dial and float. The bowl is filled with liquid that has minimum volume and viscosity changes with temperature variations. Some compasses have an expansion bellows to allow for fluid expansion. The bowl supports a metal float that has two small magnets attached to it. A graduated scale, called a card, is wrapped around the float and viewed through a glass window with a lubber line across the center of the glass. The float and card assembly has a hardened steel pivot in its center that rides inside a special, spring-loaded, hard-glass jewel cup. The buoyancy of the float takes most of the weight off the pivot, and the fluid dampens the oscillation of the float and card. This jewel-and-pivot type of mounting allows the float to freely rotate and tilt about 18 degrees. Compass indications are erratic and unreliable at steeper bank angles. 1-37. The compass card is marked with letters representing the cardinal directions—north, east, south, and west—and a number for each 30 degrees between these letters. The final “0” is omitted from these directions as in the following examples. Examples of Compass Card Degree Equivalents 3 = 30 degrees 6 = 60 degrees 33 = 330 degrees Figure 1-15. Magnetic compass 1-38. There are long and short graduation marks between the letters and numbers, with each long mark representing 10 degrees and each short mark representing 5 degrees. The numbers and letters on the graduated scale are marked to allow the aviator to view the direction being flown. The markings appear backward from conventional compasses that are viewed from above. COMPASS ERROR 1-39. Compass errors are plentiful and can make straight and level flight very challenging. These errors can range from variations, deviations, and dip errors. 1-12 TC 3-04.5 7 April 2017  Flight Instruments and Systems VARIATION 1-40. The Earth rotates about its geographic axis, and maps and charts are drawn using meridians of longitude that pass through the geographic poles. Directions measured from the geographic poles are called true directions. The north magnetic pole, to which the magnetic compass points, is not collocated with the