5.3 Electronic Flight Displays & Flight Director Systems

Electronic Flight Displays & Flight Director Systems

Core Airline Transport Principle: Modern glass cockpits replace discrete electro-mechanical dials with integrated Electronic Flight Instrument Systems (EFIS). For the airline transport pilot, glass cockpit mastery requires moving beyond basic instrument scanning to active automation monitoring—treating the Flight Mode Annunciator (FMA) as the primary source of operational truth and responding systematically to tiered EICAS/ECAM crew alerting messages.

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1. EFIS Architecture and Primary Flight Display (PFD) Symbology

The Primary Flight Display (PFD) centralizes all primary flight parameters onto a single, high-resolution Active Matrix Liquid Crystal Display (AMLCD) or synthetic vision screen.

+-----------------------------------------------------------------------------+
|                        PRIMARY FLIGHT DISPLAY (PFD) LAYOUT                  |
|                                                                             |
|   +---------------------------------------------------------------------+   |
|   | [ THR REF ] | [ LNAV ] | [ VNAV PATH ] | [ CMD 1 ] | [ LAND 3 / CAT 3 ] | <- FMA Window
|   +---------------------------------------------------------------------+   |
|                                                                             |
|   SPEED TAPE        ATTITUDE INDICATOR / PITCH LADDER        ALTITUDE TAPE  |
|   +---------+                 +-----------+                  +------------+ |
|   | [ 290 ] |                 |   /---\   | Pitch Limit      |  [ 35000 ] | | Target Alt
|   |         |                 |  +=====+  | Indicator (PLI)  |            | |
|   |===280===| <-- Speed Bug   |---|---|---|                  |===34000====| | Current Alt
|   |  (272)  | <-- Actual IAS  |     o     | Aircraft Symbol  |   (34020)  | | Rolling Count
|   |   |     |                 |-----------| Horizon Line     |     |      | |
|   |   v     | <-- 6s Trend    |   \___/   |                  |     v      | | 6s Trend
|   |         |                 +-----------+                  +------------+ |
|   | [====]  | Stall Amber     |     ^     | Roll Pointer     |   [ 29.92] | | Baro Setting
|   | [XXXX]  | Stall Red Tape  |    / \    | Slip/Skid Trapez | +----------+ |
|   +---------+                 +-----------+                  | VSI Scale  | |
|   MACH .802                                                  |   +1200    | |
|                                                              +------------+ |
|                       [ HEADING COMPASS TAPE / ROSE ]                       |
|                             [ 2 7 0 ] MAG                                   |
+-----------------------------------------------------------------------------+

Detailed PFD Symbology Components

1. Dynamic Airspeed Tape (Left): Displays indicated airspeed on a vertical scrolling tape.
   • Speed Trend Vector: A magenta line extending from current airspeed, predicting airspeed in 6 seconds based on current longitudinal acceleration.
   • $V_1, V_R, V_2, V_{\text{REF}}$ Speed Bugs: Takeoff and landing reference targets entered via FMC.
   • Minimum Clean Speed (Green Dot / Amber Bug): Best lift-to-drag ($L/D_{\text{max}}$) speed for operating without flaps.
   • Low-Speed Buffet / Stick Shaker Barber Pole (Red/Amber Tape): Top of the amber band indicates minimum maneuvering speed (providing a $1.3g$ bank margin to stick shaker); top of the red/black barber pole indicates stick shaker activation speed ($V_{\text{SW}}$).
   • High-Speed Maximum Operating Limit ($V_{\text{MO}} / M_{\text{MO}}$): Red and black barber pole at the top of the tape indicating maximum structural/certification limit.
2. Attitude Indicator and Pitch Ladder (Center): Shows pitch and roll with $2.5^\circ$ pitch increments.
   • Pitch Limit Indicator (PLI / "Eyebrows"): Amber brackets indicating the exact pitch attitude at which the stick shaker will activate at the current angle of attack and G-load.
   • Roll Pointer & Slip/Skid Trapezoid: The slip/skid indicator is split beneath the roll triangle; lateral displacement indicates uncoordinated flight (step on the trapezoid to center it).
3. Altitude Tape & Vertical Speed Indicator (Right): Displays barometric altitude, target MCP altitude, and vertical speed.
   • Altitude Trend Vector: Predicts altitude in 6 seconds based on vertical speed.
   • Rolling Barrel Digits: Provides rapid visual rate feedback during high-rate climbs and descents.
   • TCAS Vertical Speed Resolution Advisory (RA) Guidance: Overlays red "no-fly" avoidance bands and green "fly-to" vertical speed targets during conflict resolution.

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2. Flight Mode Annunciator (FMA) Discipline & Automation Protocol

[!IMPORTANT] The Golden Rule of Glass Cockpits: The Flight Mode Annunciator (FMA) located at the top of the PFD is the sole operational indicator of what the autoflight system is actually doing. The Mode Control Panel (MCP) or Flight Control Unit (FCU) only displays what the pilot requested; the FMA displays what the aircraft accepted and engaged.

+-----------------------------------------------------------------------------+
|                        STANDARD FMA COLUMN ARCHITECTURE                     |
|                                                                             |
|   Col 1: Autothrottle | Col 2: Lateral Mode | Col 3: Vertical Mode | Col 4: |
|   --------------------+---------------------+----------------------+ Status |
|   [ THR REF / SPEED ] |  [ LNAV / HDG SEL ] |  [ VNAV PATH / FLCH ] | [CMD 1]|
|   (Engaged - Green)   |  (Engaged - Green)  |  (Engaged - Green)   | [CAT3] |
|                       |                     |                      |        |
|                       |  [ LOC Armed ]      |  [ G/S Armed ]       |        |
|                       |  (Armed - White)    |  (Armed - White)     |        |
+-----------------------------------------------------------------------------+

FMA Operating Rules and Annunciation Conventions

1. Color Conventions:
   • Green (or Cyan on some displays): Active, currently Engaged mode controlling the aircraft.
   • White (or Cyan/Amber on some displays): Armed mode waiting for capture criteria (e.g., LOC armed while intercepting localizer).
2. Mode Change Highlighting: Whenever an FMA mode changes (e.g., from HDG SEL to LNAV or ALT HOLD to VNAV PTH), a green or white box surrounds the new annunciation for 10 seconds.
3. Verbal Callout Requirement (CRM): Standard Operating Procedures (SOP) require the Pilot Flying (PF) to verbally call out all FMA box changes (e.g., "Checked, LNAV, VNAV PATH"), and the Pilot Monitoring (PM) must visually verify the FMA and respond "Checked".

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3. Navigation Display (ND) Modes and Sensor Overlays

The Navigation Display (ND) presents horizontal situational awareness across multiple selectable operational formats.

+-----------------------------------------------------------------------------+
|                           NAVIGATION DISPLAY (ND) MODES                     |
|                                                                             |
|   1. ROSE MODE (VOR / ILS / NAV):                                           |
|      - Full 360° compass rose centered on the aircraft symbol.              |
|      - Shows raw radio navigation data: VOR radials, ILS localizer/glideslope|
|        deviation bars, and bearing pointers (ADF/VOR).                      |
|      - Primary use: Raw-data approaches, holding patterns, manual tracking. |
|                                                                             |
|   2. ARC / MAP MODE:                                                        |
|      - Expanded 90° or 120° forward sector centered ahead of aircraft.       |
|      - Displays active FMC flight plan: active leg (Magenta), inactive legs |
|        (White/Cyan), waypoints with speed/altitude constraints.             |
|      - Primary use: Standard departure, cruise, and arrival navigation.     |
|                                                                             |
|   3. PLAN MODE:                                                             |
|      - Static, True North-up display of the flight plan route.              |
|      - Aircraft symbol is NOT centered; route is stepped through waypoint by|
|        waypoint using the FMC CDU `LEGS` or `STEP` page.                    |
|      - Primary use: Preflight route verification and inflight reroute checks.|
+-----------------------------------------------------------------------------+

+-----------------------------------------------------------------------------+
|                        TACTICAL SENSOR OVERLAYS ON MAP MODE                 |
|                                                                             |
|   [ Weather Radar (WXR) ]  --> Green (Light), Yellow (Mod), Red (Heavy),    |
|                                Magenta (Turbulence / Windshear Warning).    |
|   [ Terrain (EGPWS/TAWS) ] --> Dotted Green (Safe), Solid Yellow (Caution   |
|                                within 60s), Solid Red (Warning within 30s). |
|   [ TCAS Traffic Targets ] --> Open Diamond (Other), Solid Diamond (Prox),  |
|                                Amber Circle (TA), Red Square (RA).          |
+-----------------------------------------------------------------------------+

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4. Engine Indicating and Crew Alerting System (EICAS / ECAM)

Transport aircraft monitor thousands of mechanical and electrical parameters using EICAS (Boeing) or ECAM (Electronic Centralized Aircraft Monitor - Airbus). Both systems enforce a rigid warning hierarchy to eliminate cockpit ambiguity during high-workload emergencies.

+-----------------------------------------------------------------------------+
|                       FLIGHT PHASE ALERT INHIBIT LOGIC                      |
|                                                                             |
|   To prevent dangerous flight crew startle and avoid unnecessary high-speed |
|   rejected takeoffs (RTO) or landing go-arounds, EICAS/ECAM automatically   |
|   inhibits non-critical cautions and advisories during critical phases:     |
|                                                                             |
|   * TAKEOFF INHIBIT: Armed from 80 knots takeoff roll until 400 ft AGL or   |
|     1,500 ft AGL / 2 minutes after liftoff. Only Level 3 Warnings (Fire,    |
|     Config, Engine Fail) will alert.                                        |
|   * LANDING INHIBIT: Active from 800 ft AGL down to touchdown / rollout.    |
+-----------------------------------------------------------------------------+

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5. Flight Director (FD) Systems & Autopilot Coupling

The Flight Director (FD) computes and displays real-time steering commands generated by the Flight Control Computers (FCC) based on active FMA modes.

+-----------------------------------------------------------------------------+
|                     FLIGHT DIRECTOR COMMAND BAR FORMATS                     |
|                                                                             |
|   CROSS-POINTER FORMAT                       SINGLE-CUE (V-BAR) FORMAT      |
|   +-------------------+                      +-------------------+          |
|   |                   |                      |                   |          |
|   |        |          |                      |        /\         |          |
|   |        |  (Roll)  |                      |       /  \ (Single|          |
|   |   -----+-----     | <-- Pitch Bar        |      /____\  Cue) |          |
|   |        |          |                      |        --         |          |
|   |        |          |                      |      -[  ]-       |          |
|   +-------------------+                      +-------------------+          |
|                                                                             |
|   * Flying the Command Bars: The pilot steers the miniature aircraft symbol |
|     to center the crosshairs or tuck the aircraft delta wing into the V-bar.|
|   * Coupling: When Autopilot is engaged (CMD), the autopilot servos follow  |
|     the FCC commands directly. In manual flight, the pilot acts as the servo|
|     closing the guidance loop manually.                                     |
+-----------------------------------------------------------------------------+

Cross-Pointer vs Single-Cue Guidance

• Cross-Pointer System: Uses independent horizontal (pitch) and vertical (roll) bars. This allows the pilot to follow a single axis command (e.g., maintaining wings level on heading) while ignoring or modifying the other axis.
• Single-Cue (V-Bar / Split-Axis) System: Uses a single integrated delta chevron. The pilot maneuvers the aircraft symbol directly into the vertex of the command bar, providing a more intuitive integrated attitude target.