EB14-6 Aircraft Instrumentation 2 - Comprehensive Study Notes (Bullet Points)

Flight Instruments Overview

• Purpose: Build a foundational understanding of common aircraft instrumentation and navigational displays used for navigation, approach, and en-route management.
• Course context: EB14-6 Aircraft Instrumentation 2; emphasis on interpreting on-board information from navigational instruments and related systems.
• Key performance objectives: Explain use of the most common aircraft systems; Describe basic on-board operating principles and interpretation of information displayed by navigational instruments/systems.

ADF, NDB, RMI, and Related Bearing Systems

• Flight instruments include Automatic Direction Finding (ADF), Very High Frequency Omni Range (VOR), TACAN, Distance Measuring Equipment (DME), Instrument Landing System (ILS), Microwave Landing System (MLS), and Satellite Navigation.
• Automatic Direction Finding (ADF)
  • Two beacons: ADF 1 and ADF 2; frequency selector to tune each beacon.
  • Radio Magnetic Indicator (RMI): displays bearing information from ADF; has active/standby selectors for ADF 1 and ADF 2.
  • In use/standby configurations allow cross-checking bearings.
• Nondirectional Beacon (NDB)
  • ADF can derive bearing to NDBs; RMI shows the magnetic bearing to NDBs from the aircraft.
  • Relative Bearing Indicator displays the relative bearing of the NDBs from the aircraft; requires more mental calculation.
  • Both ADF and NDB bearing readings require wind-aware situational awareness (drift, wind direction).
  • Practical use: ADF can be used to execute a Non-Precision Approach (NDB Approach).
• Practical considerations
  • Drift and wind correction are essential for accurate navigation using ADF/NDB.
  • ADF/NDB approaches rely on bearing geometry and wind factors; pilots must interpret drift and altitude constraints accordingly.

VOR, RMI, and the Horizontal Situation Indicator (HSI)

• VOR overview
  • Navigation sources: NAV 1, NAV 2; Standby frequency; In-use/standby selector; RMI allows changing between ADF and VOR.
  • VOR provides radials (FROM) and can provide TO/FROM indications depending on course selection.
• RMI and HSI concepts
  • The RMI displays a magnetic bearing from navigation aids (ADF or VOR) relative to the aircraft.
  • Horizontal Situation Indicator (HSI): combines course information with a deviation indicator to show track vs. desired course.
  • Course selector rotates the head and, in some displays, the tail of the CDI needle; CDI (Course Deviation Indicator) shows deviation from the selected course.
  • Courses can be from VOR, ILS, MLS, or any Area Navigation (RNAV) source.
• CDI and Course/Deviation display
  • CDI (Course Deviation Indicator) visualizes how far off the selected course the aircraft is.
  • H.S.I. integrates bearing information with the course indicator for easier interpretation than a stand-alone CDI.
• Typical example (VOR readout)
  • Course 045 TO the VOR, indicating a TO indication and a radial FROM of 225 when tracking out from the VOR on 225 radials.
  • Course selectors and flags are used to manage TO/FROM relationships and alignment with the VOR signal.
• Practical takeaways
  • VOR readings are generally more accurate than NDB/ADF bearings.
  • The HSI/CDI reduces mental math by presenting course guidance visually.

DME and Distance Information

• Distance Measuring Equipment (DME)
  • Provides distance to the navigation aid (VOR, VOR/DME, or TACAN/DME stations).
  • Often remotely tuned to an associated navigation unit (DME reads distance tied to NAV source).
  • DME is typically paired with VOR or ILS for distance information and ETA/ETD planning.
• Ground Speed and ETA/ETE
  • DME readings support distance-to-go calculations and ETA estimates when combined with ground speed data from navigation systems or weather inputs.
• Key note
  • DME is a crucial component for precision timing in en-route and approach phases and enabling Non-Precision Approaches when aligned with VOR/NDB data.

Instrument Landing System (ILS) and Microwave Landing System (MLS)

• Instrument Landing System (ILS)
  • Provides azimuth information similar to VOR, but without TO/FROM flags.
  • Glidepath (G/P) information is provided to guide the aircraft vertically on the approach path.
  • Marker beacons (OM – Outer Marker, MM – Middle Marker, IM – Inner Marker) may accompany ILS as part of traditional approaches.
  • On Track and On Glide indications appear on the HSI during approach guidance.
• Marker beacons
  • Outer Marker (OM), Middle Marker (MM), Inner Marker (IM) provide altitude/position cues along the final approach path.
• Localizer and Glidepath indicators
  • Localizer information aligns with runway centerline; Glidepath guides descent angle.
• MLS (Microwave Landing System)
  • Receiver data can feed the HSI for straight approaches or the Flight Director to provide curved approaches.
  • MLS data can be used to generate curved approach paths, with straight approaches supported similarly to ILS.
  • MLS was intended to supersede ILS but is now largely unused in many fleets.
• Cockpit indications
  • ILS/MLS approaches are normally accompanied in the UK by DME.
  • Older systems used Fan Markers; modern cockpits typically rely on EFIS/Flight Director indicators (H.S.I. and/or Flight Director).
• Practical takeaways
  • ILS enables precision approaches; MLS offers curved approaches via Flight Director on the Attitude Indicator.
  • Modern workflows emphasize HUD/EFIS integration for approach guidance and situational awareness.

Attitude and Navigation Displays (EFIS, EADI, EHSI, HUD)

• Electronic Flight Information System (EFIS)
  • Core components: Electronic Attitude and Direction Indicator (EADI) and Electronic Horizontal Situation Indicator (EHSI).
  • Data sources: Air Data Computer (ADC), Flight Management System (FMS), Flight Director, Internal Reference System (IRS), Weather Radar, Lightning Sensors.
  • Output: Left and right EFIS displays serve as primary crew information streams; captain’s AI may be duplicated on Head-Up Display (HUD) if fitted.
  • Standby EFIS: Standby Instrumentation is used when both EFIS displays are unserviceable; not all aircraft have standby EFIS (e.g., some jets do not have a standby EADI).
• Electronic Attitude and Direction Indicator (EADI)
  • Provides attitude information and is part of the EFIS family; duplicates can exist to provide redundancy.
• Electronic Horizontal Situation Indicator (EHSI)
  • Provides heading and navigation information; part of the EFIS pair with EADI.
• Heads-Up Display (HUD)
  • HUD provides runway and cockpit information in the pilot’s line of sight; useful in poor weather conditions; data can be duplicated from EADI.
  • HUD is a reflection of the cockpit’s data feed, enabling continued situational awareness on approach and landing.
• Standby instrumentation
  • Important when left/right EFIS disfunctional; includes a Standby EADI/AI and related indicators; ensures safe landing capability with reduced information.
• Interim and final summaries related to EFIS
  • EFIS data originates from multiple sources and is fed to left and right sides with redundancy.
  • Standby instruments augment or replace EFIS in emergencies; HUD can duplicate essential AI data when fitted.

External Displays and Weather Information

• Weather Radar
  • Radar returns are proportional to water droplet size; larger droplets indicate greater atmospheric instability.
  • Weather radar can also be used for navigation (coastlines mapping, etc.) and has modes such as Mapping.
  • Displays use color-coding to indicate severity of weather; pilots should avoid red or magenta areas.
  • Radar antenna can be tilted and gyro-stabilised to maintain display stability with aircraft attitude changes.
• Colour coding and cockpit cues
  • Weather radar displays in colors similar to aviation traffic-light conventions to indicate severity and movement of weather cells.
• Enhanced GPWS/EGPWS display integration
  • EGPWS provides seven modes according to flight stage; terrain can be overlaid on EFIS or weather radar displays to aid terrain awareness.
  • Modern systems highlight terrain silhouettes and MSAs on EFIS/EFIS-like displays for improved decision-making.

Engine Instruments and Engine-Related Systems

• Engine instruments
  • Key measurements: Fuel quantity, fuel flow, fuel pressure, fuel temperature; oil quantity, oil pressure, oil temperature; engine power and limitations; electrical power.
  • Typical example panel reference: Central Engine Panel (as seen on B727 example).
• Units of measurement
  • Quantities: kilos, pounds, litres, US or Imperial gallons; could also be described in hours.
  • Pressure: psi, kg/cm^2, or BAR.
  • Flow: kg/hour, lb/hour, etc.; Temperature: °C or °F.
  • Electrical: Volts and Amps; AC/DC characteristics vary by aircraft.
• Fuel system and fuel management
  • Example values (typical):
  • Fuel Pressure: $37.2 ext{ psi}$ to $37.7 ext{ psi}$ (varies by engine);
  • Fuel Flow: $1210 ext{ kg/h}$ or $1200 ext{ kg/h}$ (per engine pair) depending on engine condition.
  • Fuel Temperature: values around $+8^ ext{°C}$ to $+7^ ext{°C}$.
  • Fuel Quantity: e.g., $8230 ext{ kg}$; later readings might show reductions (e.g., to $4810 ext{ kg}$ after an hour).
  • Fuel quantity must be checked at least once per hour and compared against actual fuel burnt to identify discrepancies (blocked fuel line, fuel leak, imminent fuel starvation).
  • Low fuel temperature outside limits prohibits flight.
• Oil system
  • Oil Pressure examples: $52.1 ext{ psi}$ and $53.9 ext{ psi}$ (two engines);
  • Oil Quantity examples: $52 ext{ L}$ and $51.3 ext{ L}$;
  • Oil Temperature examples: around $+65^ ext{°C}$ to $+67^ ext{°C}$;
  • Engine lubrication: Oil is pumped to bearings; issues include line blockage, overfilling (high pressure), or ruptured/blocked lines (low pressure).
• Powerplant and turbine limits
  • Jet and turbo-prop engines use gas turbine technology; main limiting factor is Exhaust Gas Temperature (EGT).
  • EGT maximum: approximately $800^ ext{°C}$; exceeding the limit risks turbine damage.
  • EGT is measured just aft of the last turbine stage.
• Engine-driven services
  • Electrical power: driven by generators/alternators; backup via battery if necessary.
  • Hydraulic power: powered by engine-driven pumps; can be backed up by hand pump, RAT (Ram Air Turbine), or nitrogen blow-down canisters in certain failures.
  • Cabin pressurisation and air conditioning: supplied by engine compressor air; metering controls cabin altitude and cabin differential to manage pressurization.
• Practical implications
  • Monitoring engine parameters helps detect faults before they affect flight; crew should consider landing if any indications show abnormal engine health.
  • RAT provides emergency hydraulic/electrical support when primary sources fail.

Electrical, Hydraulic, and Pneumatic Systems

• Electrical power architecture
  • Aircraft electrical power is generated by alternators/generators; failure of a generator/alternator reduces electrical services.
  • Battery power may be the sole power source in some scenarios.
• Hydraulic power and systems
  • Hydraulic systems actuate essential surfaces and systems: flaps, landing gear, flight controls, speed brakes/spoilers, wheel brakes.
  • Hydraulic pressure and fluid quantity are monitored to ensure adequate operation.
• Pneumatic (pressurisation and air conditioning)
  • Pressurisation uses compressed air from the engine compressor; cabin altitude is controlled by metering the vented air; differential pressure is monitored to protect the aircraft structure.
  • Failure or over-pressurisation can lead to automatic depressurisation and possibly emergency descent.
• Ram Air Turbine (RAT)
  • RAT provides emergency hydraulic/electrical power when primary sources fail; physical deployment is indicated on some systems.

Transponder, TCAS, GPWS/EGPWS, and Safety Systems

• Transponder/codes
  • Uses SSR for identification, altitude reporting, and declaring radio failure or an emergency.
  • Codes:
  • 7500: Hijack
  • 7600: Radio/RTF failure
  • 7700: Emergency
  • SSR codes are entered as digits 0–7 (octal system).
  • Basic modes include Squawk Ident, Squawk mode A, mode A & C, and standby modes.
• Traffic Collision and Avoidance System (TCAS)
  • TCAS system interoperability with ATC is covered in separate lessons; not detailed in these slides.
• Ground Proximity Warning System (GPWS) and Enhanced GPWS (EGPWS)
  • GPWS is an audible warning system based on radar altimeter data; typical warnings include the “Whoop-Whoop” pull-up cue.
  • EGPWS adds seven modes according to flight phase and terrain awareness enhancements; terrain and weather display may be shown on EFIS or weather radar displays.
• Standby instruments and safety redundancy
  • Standby instrumentation is used when EFIS displays fail; ensures continued ability to land, though with high workload.

Weather, Flight Deck Displays, and Human Factors

• Weather radar (detailed)
  • Provides weather cell information with color coding to indicate severity; pilots should avoid red/magenta areas.
  • Antenna tilting gyro-stabilisation helps maintain stable presentation with aircraft attitude changes.
  • Weather radar data can be used for mapping and situational awareness (coastlines, weather patterns).
• Projected cockpit displays and HUDs
  • HUD provides critical flight data while keeping the pilot’s line of sight toward the runway; particularly valuable in poor weather.
  • Projector/hud configurations show runway cues, flight director cues, and AI data.
• EFIS advantages and potential drawbacks
  • Advantages: integrated data feed from multiple sensors; duplication of essential information on left/right displays; HUD option for enhanced situational awareness.
  • Disadvantages: potential over-reliance on EFIS; increased workload if failures occur; pilot problems during EFIS failure require quick adaptation.
• Standby EFIS and safety considerations
  • Standby instrumentation provides minimal but crucial information to enable safe landing when EFIS fails; crew training emphasizes using standby tools effectively.
• Interconnection and data sources
  • EFIS data flows from ADC, FMS, Flight Director, IRS, Weather Radar, and lightning sensors; two separate data paths (left and right) support redundancy.

Interim and Final Summaries (Key Takeaways)

• Interim navigation summaries
  • ADF provides bearing information to/from beacons, requiring wind-drift awareness.
  • VOR displays radials and TO/FROM relationships; VOR generally more accurate than NDB.
  • H.S.I. minimizes mental calculation; CDI shows deviation from the desired course.
  • DME provides distance, ground speed indicators, and ETA/ETE information; normally remotely tuned to VOR/ADF/VOR-DME.
• Interim instrument deployment
  • ILS/MLS provide precision approach capability; approaches can be manual or coupled to autopilot; DME often accompanies UK operations.
  • MLS supports curved approaches via Flight Director; straight approaches via HSI and/or Flight Director.
• Final synthesis: VOR/DME/ADF vs ILS/MLS
  • Non-precision approaches can be executed with ADF/VOR/VOR-DME, with CDI/HSI supporting track guidance; DME enhances distance/ETA calculations.
  • Precision approaches use ILS or MLS, with DME support and Flight Director/AI guidance; EFIS/HUD integration enhances situational awareness.
  • En-route navigation typically relies on INS, GPS, and Area Navigation; FMS provides waypoint-based planning, distance, and ETA/ETE information.
• Final cautions and synthetic overview
  • Final navigational systems rely on redundancy, cross-checks, and cross-instrument verification to mitigate faults.
  • Operators should be mindful of the aging or obsolescence of certain systems (e.g., MLS usage in some fleets) and rely on contemporary EFIS/HUD capabilities for optimal performance.

Final Summary (Condensed)

• VOR/DME/A.D.F. provide radial and distance information with varying accuracy; VOR/DME is typically more accurate than NDB, and ADF/NDB approaches require wind drift awareness. H.S.I. reduces mental calculation while CDI provides deviation guidance.
• ILS/MLS provide precision approach capabilities; MLS offers curved approaches and data can feed Flight Director; older systems used marker beacons.
• En-route navigation relies on INS, GPS, and Area Navigation; FMS provides waypoint, distance, and ETA/ETE information, with data feeds from various aircraft sensors.
• EFIS/EADI/EHSI/HUD provide redundancy, with standby instrumentation available for safe landings during failures; weather radar and GPWS/EGPWS enhance terrain and weather awareness.
• Engine instruments (fuel, oil, EGT) and engine-driven services (electrical, hydraulic, RAT) are critical for safety and performance; max EGT generally around $E_{GT, ext{max}} \approx 800^ ext{°C}$ and fuel management requires routine checks (at least hourly) to detect anomalies.
• Safety systems (transponder squawks, TCAS, GPWS/EGPWS) form an integrated safety envelope; TCAS details are covered in separate sessions, while GPWS/EGPWS provide terrain awareness and alerting.
• Electrical and environmental control systems (AC/DC power, pressurisation, air conditioning) are essential for airborne operations and crew comfort; RAT provides a critical fallback in power failures.

Notes on Anomalous Content

• Slide containing “CHEMTRAILS” (Page 57) appears unrelated to aircraft instrumentation and should be disregarded as non-technical course content.

Useful Formulas and Values (as reference)

• Typical EGT limit for engine protection: E_{GT, ext{max}}
  oughly= 800^ ext{°C}
• Common unit examples (for reference):
  • Fuel pressure: $37.2 ext{ psi} ext{ to } 37.7 ext{ psi}$
  • Fuel flow: $1210 ext{ kg/h} ext{ to } 1200 ext{ kg/h}$
  • Temperature readings: around $+7^ ext{°C} ext{ to } +8^ ext{°C}$
  • Oil pressure: $52.1 ext{ psi} ext{ to } 53.9 ext{ psi}$
  • Oil temperature: around $+65^ ext{°C} ext{ to } +67^ ext{°C}$
  • Aircraft electrical: $114 ext{ V}_{ ext{AC}}; 201 ext{ A}; 404 ext{ Hz}$; DC: $28.4 ext{ V}$
• Basic ETA/ETE concept (navigation planning):
  • $ext{ETA} = \frac{ ext{Distance to go}}{ ext{Ground Speed}}$
  • Practical use: combine DME distance with speed to estimate arrival at a waypoint or destination