Electronic Instruments
Introduction
As the operation of transport aircraft and their systems has become increasingly automated and, at the same time, the number of flight deck crew members has been decreased, it has become impossible for the crew to monitor and control the automated processes using conventional instrument displays.
To overcome this situation the traditional form of instrument has been almost entirely replaced by computer-generated displays projected upon a few cathode ray tube (CRT) screens. These screens usually combine the features of a number of the conventional instruments and, especially in the case of engine and system displays, normally only show the more essential information, with less critical information being selected by the pilots only as required.
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The principal electronic display systems in use are the Electronic Flight Instrument System (EFIS) for the presentation and control of navigational information and, for presentation of engines and systems information, either the Engine Indicating and Crew Alerting System (EICAS) or Engine Centralised Aircraft Monitoring (ECAM).
EICAS is generally used in aircraft of American manufacture and ECAM in Airbus Industries aircraft.
Electronic Flight Instrument Systems (EFIS)
The complete EFIS installation is made up of left (Captain), and right (First Officer), systems.
Each system in turn is comprised of:
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Electronic Attitude Director Indicator (EADI) or Primary Flight Display (PFD)
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Electronic Horizontal Situation Indicator (EHSI) or Navigation Display (ND)
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Symbol Generator (SG)
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Remote Light Sensor Unit
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Control Panel
A third (centre) symbol generator is also incorporated so that its drive signals may be switched to either the left or right display units in the event of failure of their corresponding symbol generators.
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The signal switching is accomplished within the left and right symbol generators, using electromechanical relays powered from an aircraft’s DC power supply, via pilot-controlled switches.
EFIS BLOCK DIAGRAM
Display Units
The display units may be Cathode Ray Tubes (CRTs) or Liquid Crystal Displays (LCDs). LCDs have the advantage of being smaller, and they generate less heat therefore need less cooling. The PFD and ND are usually identical units to facilitate spares commonality and are often interchangeable with the systems display units (EICAS or ECAM).
Symbol Generators (SGs)
Symbol generators provide the analogue, discrete, and digital signal interfaces between an aircraft’s systems, the display units and the control panel, and they also perform symbol generation monitoring, power control and the main control functions of the ‘EFIS’ overall.
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The Remote Light Sensor
The Remote Light Sensor is a photodiode device which responds to ambient light conditions on the flight deck, and automatically adjusts the brightness of the CRT displays to an acceptable level.
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Control Panel
The control Panel consist of the following switches
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Mins (Minumum control)
The minimums controls is used to select and set the radio and barometric minimum altitude. These are the minimums controls:
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Minimums reference selector
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Minimums selector
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Minimums reset switch.
The outer control is the minimums reference selector. It selects either radio or barometric (baro) as the reference for the minimum altitude. The middle control is the minimums selector and it sets the altitude.
The inner control is the minimums reset (RST) switch. This switch resets the radio altitude alert when the minimums reference selector is in the radio position.
FPV (flight path vector)
The flight path vector (FPV) switch lets you show the FPV symbol on the attitude display.
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MTRS (meters switch)
The meters switch (MTRS) is an alternate action switch. When you select MTRS, the Altitude and the MCP select altitude indications show in meters and feet.
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Baro
The barometric controls select and set the barometric reference. These are the barometric controls:
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Barometric reference selector
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Barometric selector
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Barometric standard switch.
The outer control is the barometric reference selector. It selects either inches of mercury (IN) or hectopascals (hPa) as the barometric reference. The middle control is the barometric selector and it sets the barometric correction. The inner control is the barometric standard switch. It selects the standard baro setting of 29.92 inches Hg or 1013 hPa.
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VOR/ADF
The VOR/ADF switch is a three position toggle switch. The switch lets you show the VOR or ADF bearing pointers on the display. These bearing pointers show on the navigation display (ND) in all modes except PLAN.
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CTR
The mode controls select the mode that shows on the ND. The mode controls are the mode selector and the centre switch. The mode selector is a four position switch. These are the four positions APP, VOR, MAP and PLN.
The centre (CTR) switch lets you show the expanded or centred mode for VOR, APP, and MAP modes.
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The range selector is an eight position selector. The selector controls the range that shows in the MAP and PLAN modes. This selector also controls the weather radar range and TCAS intruder symbol range in all modes.
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TFC (Traffic)
The traffic (TFC) switch lets you show TCAS information on the display.
Weather Radar Switch
The WXR switch turns on the weather radar and allows the weather radar data to show in the expanded modes and centred map mode. Weather radar does not show in the plan mode.
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Terrain Switch
The TERR switch lets you show enhanced ground proximity warning system displays on the ND.
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MAP Switch
The map switches let you show additional map information in the MAP mode. These are the map switches:
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STA for navigation aids not in the route
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WPT for waypoints not in the route
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ARPT for airports not in the route
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DATA for altitude and ETA of route waypoints
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DATA for selection of vertical situation display and for a range setting of 160 nm or greater, altitude and ETA of route waypoints
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POS for position comparison information
EFIS CONTROL PANEL
The Electronic Attitude and Direction Indicator (EADI)
The EADI screen displays aircraft attitude in pitch and roll in the conventional format of an artificial horizon divided horizontally, with the upper half coloured blue and the lower half coloured yellow (or sand).
The source data for the attitude indications are the aircraft inertial reference systems. The display also includes flight director command bars, ILS glideslope and localiser deviation indications, and deviation indication from a selected airspeed.
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Radio altitude, decision height and operating modes of the automatic flight and autothrottle systems are also displayed on the EADI screen.
ELECTRONIC ATTITUDE AND DIRECTION INDICATOR (EADI)
Between 1000 ft and 2500 ft, radio altitude is displayed in digital format only, but below 1000 ft above ground level (agl) the display changes to include an white analogue and circular scale calibrated in increments of 100 ft display as well. The selected decision height is then displayed as a magenta-coloured marker on the outer scale. As height agl decreases the white circular scale segments are progressively removed in an anti-clockwise direction.
The decision height (DH) can be set by a control knob on the EFIS control panel and the selected DH is digitally displayed on the EADI screen and a magenta coloured marker appears at the selected height on the circular scale.
At 50 ft above DH an aural chime begins to sound and its frequency increases until DH is reached. At this point the circular radio altitude scale and the DH marker both change colour to amber (yellow) and flash for several seconds.
Pressing the EADI control panel DH RST button will cancel the alert chime, stop the marker flashing and change the DH displays back to their normal colour.
DECISION HEIGHT INDICATIONS
Deviation beyond normal localizer and glide slope limits cause the scales to change colour to amber and the pointer to flash, which ceases if the aircraft returns to within limits.
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The Speed Error Display consists of a pointer which moves relative to a deviation scale to show difference between actual speed and commanded speed.
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Various information are displayed on the EADI displays in various colours which are as follows
EADI COLOURS DISPLAYS
The Electronic Horizontal Situation Indicator (EHSI)
The EHSI, presents a display of flight navigational information and progress in one of nine possible modes, selected from the HSI section of the EFIS control panel.
The modes available are as follows:
MAP
The display used for en-route navigational information and the one most commonly selected in cruise flight. The display shows features ahead of the aircraft, with the aircraft symbol appearing at the bottom of the display.
CTR MAP
Essentially the same as MAP, but the display is centred upon the aircraft current position, with an aircraft symbol in the centre of the display.
PLAN
This display shows the planned route with waypoints and is principally used when entering waypoints into the flight management system (FMS) computer before flight or when making changes to the planned route.
FULL VOR/FULL ILS
These displays are basically identical and show a compass rose with heading and deviation indications that follow conventional formats. They are used when checking aircraft track against a VOR bearing or ILS localiser. With VOR selected the display would be essentially the same, except that the in-use VOR would be indicated in the lower left corner, where ILS appears in the diagram.
EXP VOR/ILS
In the expanded mode the information displayed is the same as in the full mode, but is in semi-map format. Only the relevant segment of the compass rose is displayed at the top of the screen, with a heading pointer. The aircraft's current (instantaneous) track is shown as a solid line extending from the aircraft symbol to the compass arc. The bearing of the selected radio aid, ILS or VOR, is shown as a solid line extending from the centre of the deviation scale to the compass arc. Again, the display with VOR selected is essentially the same. In either case the weather radar picture can be superimposed upon the display, if required.
EXP NAV/FULL NAV
These two modes display lateral and vertical navigational information in much the same format as a conventional HSI. Expanded NAV mode shows a compass arc, whereas full NAV mode displays a full compass rose and does not permit the weather radar display to be superimposed, exactly as with the expanded and full VOR/ILS modes.
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The symbols used in EHSI are as follows
EHSI SYMBOLS
Various information are displayed in on the EHSI in various colours which are as follows
EHSI COLOURS DISPLAYS
MAP Mode
The mode used normally is the MAP display, which, in conjunction with the flight plan data programmed into a flight management computer, displays information against a moving map background with all elements to a common scale.
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The symbol representing the aircraft is at the lower part of the display, and an arc of the compass scale, or rose, covering 45 degrees on either side of the instantaneous track, is at the upper part of the display.
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Heading information is supplied by the appropriate inertial reference system and the compass rose is automatically referenced to magnetic north (via a crew-operated MAG/TRUE selector switch) when between latitudes 73°N and 65°S, and to true north when above these latitudes. When the selector switch is set at TRUE the compass rose is referenced to true north regardless of latitude.
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The aircraft active route as derived from the FMC is shown as a magenta coloured line joining the waypoints. The active waypoint (the one the aircraft is currently navigating towards) is shown as a magenta coloured star. The other waypoints making up the active route are called inactive waypoints and are shown as a white star. Both are identified by name.
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Distance to next waypoint and time at next waypoint are shown at the top of the display Weather radar (WXR) return data and range arcs are displayed when the WXR switch is on. Turbulence mode (+T) may be available.
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Indications of other data such as wind speed and direction, lateral and vertical deviations from the selected flight path are also displayed.
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The flight management computer (FMC) can predict events by combining current ground speed and lateral acceleration to show a display of either a curved trend vector, white, (during turns) or a range to altitude arc, green, (during climb or descent). Off route waypoints, airports, nav aids can all be shown in their relative position to the aircraft’s progress and selected range. Additional waypoint information can be displayed when selected: altitude, time etc.
EHSI MAP MODE DISPLAY
PLAN Mode
In ‘PLAN’ mode a static map background is used with active route data orientated to true north. Any changes to the route may be selected at the keyboard of the flight management computer, and the display shown on the EHSI, so they can be checked before they are entered into the FMC.
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The top portion of the EHSI remains the same as in the map mode.
This mode allows the pilot to review the planned route by using the FMC / CDU LEGS page. Weather radar display data is inhibited.
No wind speed or direction information is shown
EHSI PLAN MODE DISPLAY
Full ILS mode
With an ILS frequency selected, the EHSI displays a full compass rose with the ILS source in the lower left and the frequency in the lower right.
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Course selection (localizer) is displayed by the magenta course needle, the tip pointing to the selected course (150). Localizer deviation is shown by the traditional deviation bar moving across a two dot left and two dot right scale. This scale is exponential.
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Glide slope deviation is shown by a magenta coloured triangle moving up and down the traditional scale on the right hand side.
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DME distance is displayed in the top left corner.
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Current heading is shown in the window and by the lubber line at the top of the compass rose (130), the current selection is Magnetic Heading as shown either side of the window.
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Current track is shown by the white triangle on the inside edge of the compass rose.
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Selected heading is shown by the magenta heading “bug” on the outer scale of the compass rose.
Wind speed and direction are shown in the lower left corner orientated to the display selection (Heading or Track, Magnetic or True).
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Weather radar displays are not available.
EHSI FULL ILS DISPLAY
Expanded ILS Mode
With an ILS frequency selected, the EHSI displays about 90° of compass rose with the ILS source in the lower left and the frequency in the lower right.
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The white triangle at the bottom of the display is the aircraft symbol.
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Selected course (track) is displayed by the magenta course needle, the tip pointing to the selected course (150). The course selectors are usually on either side of the autoflight main control panel (one for the Captain and one for the First Officer). Localizer deviation is shown by the traditional deviation bar moving across a two dot left and two dot right scale. Glide slope deviation shown on the right again in the traditional fashion.
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DME distance is displayed in the top left corner.
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Current heading is shown in the window and by the lubber line at the top of the compass rose. In this case the heading is 130° Magnetic, as indicated by markings either side of the window. Current track is shown by the white line from the tip of the aircraft symbol to the inside edge of the compass rose.
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Selected heading is shown by the magenta heading “bug” on the outer scale of the compass rose. Wind speed and direction are shown in the lower left corner orientated to the display selection (Heading or Track, Magnetic or True).
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Weather radar displays are available, when selected “on”, range arcs are also visible. Weather radar is shown in three colours: green, yellow and red, green being the least turbulence, red being the worst. If TURBULENCE MODE is available, it is shown as magenta, the area of greatest activity in the cloud.
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The range of the display can be selected on the control panel; half scale range is displayed (10 NM) so this display is selected to 20 NM. The outer arc of the compass rose is the furthest range from the aircraft.
EHSI EXP ILS DISPLAY
Full VOR Mode
With a VOR frequency selected, the EHSI displays a full compass rose with the VOR source in the lower left and the frequency in the lower right.
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Course selection is displayed by the magenta course needle, the tip pointing to the selected course (150). Course deviation is shown by the traditional deviation bar moving across a two dot left and two dot right scale.
A TO / FROM pointer is shown in addition to the TO /FROM annunciation. DME distance displayed in the top left corner.
Current heading is shown in the window and by the lubber line at the top of the compass rose (130), the current selection is Magnetic Heading as shown either side of the window.
Current track is shown by the white triangle on the inside edge of the compass rose.
Selected heading is shown by the magenta heading “bug” on the outer scale of the compass rose.
Wind speed and direction are shown in the lower left corner orientated to the display selection (Heading or Track, Magnetic or True).
Weather radar displays are not available.
EHSI FULL VOR DISPLAY
Expanded VOR Mode
With a VOR frequency selected, the EHSI displays about 90° of compass rose with the VOR source in the lower left and the frequency in the lower right.
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The white triangle at the bottom of the display is the aircraft symbol.
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Selected course (track) is displayed by the magenta course needle, the tip pointing to the selected course (150). The course selectors are usually on either side of the autoflight main control panel (one for the Captain and one for the First Officer). Course deviation is shown by the traditional deviation bar moving across a two dot left and two dot right scale.
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A TO /FROM annunciation is shown.
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DME distance is displayed in the top left corner.
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Current heading is shown in the window and by the lubber line at the top of the compass rose (130), the current selection is Magnetic Heading as shown either side of the track window. Current track is shown by the white line from the tip of the aircraft symbol to the compass arc. Selected heading is shown by the magenta heading “bug” on the outer scale of the compass rose. Wind speed and direction are shown in the lower left corner orientated to the display selection (Heading or Track, Magnetic or True).
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Weather radar displays are available; when selected “on”, range arcs are also visible. Weather radar shows three colours: green, yellow and red, green being the least turbulence, red being the worst. If turbulence mode is available, it is shown as magenta, the area of greatest activity in the cloud. The range of the display can be selected on the control panel, half scale range is displayed (10 NM) so this display is selected to 20 NM. The outer arc of the compass rose is the furthest range from the aircraft.
EHSI FULL ILS DISPLAY
Engine Indicating and Crew Alerting System (EICAS)
The EICAS system is an electronic display consisting of two CRT screens mounted vertically, one above the other, and usually positioned centrally on the cockpit console, where they are easily visible to either pilot. The displays are capable of presenting all the engine and system operating data traditionally displayed by a mass of dials at a flight engineer's station, with facilities for displaying a great deal more information besides.
The upper of the two screens, known as the primary display, normally shows only essential (i.e. primary) engine information such as engine pressure ratio (EPR), turbine spool speed (N1) and exhaust gas temperature (EGT) and warning and caution messages.
The lower of the two screens, known as the secondary display, may be used to display less important (secondary) information i.e. N2 speed, fuel flow, oil quantity, pressure and temperature, and engine vibration and details of abnormal engine. In addition, the status of non-engine systems, e.g. flight control surface positions, hydraulic system, APU, etc., can also be displayed together with aircraft configuration and maintenance data.
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The EICAS displays are generated by two computers that are continuously receiving operating data from the engines and the various aircraft systems. At any given time only one computer is operating the system, whilst the other functions as a standby. A display selection panel enables the pilots to select one of two operating modes, operational or status. A third mode, maintenance, is available on the ground, specifically for use by maintenance personnel.
EICAS BLOCK DIAGRAM
Seven colours are produced by the CRTs and they are used as follows
EICAS COLOUR DISPLAYS
Display Modes
EICAS is designed to categorize displays and alerts according to function and usage, and for this purpose there are three modes of displaying information:
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Operational Mode
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Status Mode
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Maintenance Mode
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Operational and Status Modes are selected by the flight crew on the display select panel, while Maintenance Mode is selected on the maintenance panel which is for the use of ground engineering staff only.
Operational mode
The operational mode displays the engine operating information and any alerts required to be actioned by the crew in flight. Normally only the upper display unit presents information, the lower one remains blank and can be selected to display secondary information as and when required.
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The upper screen displays the primary engine information like N1 speed, EGT, and warning and caution messages.
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The rows of ‘V’s shown on the upper display unit only appear when secondary information is being displayed on the lower unit.
EICAS PRIMARY DISPLAY
EICAS Alert Message
In the event of an abnormal condition developing an alert message will appear on the upper screen and the lower screen will display details of the abnormal condition in analogue and digital format.​
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When an abnormal engine or system operating condition develops, an appropriate warning or cautionary message will appear on the left side of the upper screen together with a row of pointers directing attention to the lower screen, where an analogue and digital display details the nature of the failure or critical condition.
The alert messages relating to abnormal conditions are prioritised by the EICAS computer so that they appear in order of importance and degree of crew response required. Up to 11 messages can be displayed, and at the following levels:
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Level A - Warning requiring immediate corrective action. They are displayed in red. Master warning lights are also illuminated, and aural warnings (e.g. fire bell) from a central warning system are given.
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Level B - Cautions require immediate crew awareness and future crew action. They are displayed in amber, and also by message caution lights. An aural tone is also repeated twice.
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Level C - Advisories requiring crew awareness. Also displayed in amber. No caution lights or aural tones are associated with this level.
EICAS ALERT MESSAGES
In order to differentiate between a caution and an advisory, the latter is always indented one space to the right.
The master warning and caution lights are located adjacent to the display units together with a ‘CANCEL’ switch and a ‘RECALL’ switch. Pushing the ‘CANCEL’ switch removes only the caution and advisory messages from the display; the warning messages cannot be cancelled. The ‘RECALL’ switch is used to bring back the caution and advisory messages into the display. At the same time, the word ‘RECALL’ appears at the bottom of the display.
A message is automatically removed from the display when the associated condition no longer exists. In this case, messages which appear below the deleted one each move up a line.
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When a new fault occurs, its associated message is inserted on the appropriate line of the display. This may cause older messages to move down one line. For example, a new caution message would cause all existing caution and advisory messages to move down one line.
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If there are more messages than can be displayed at one time, the whole list forms what is termed a ‘page’, and the lowest message is removed and a page number appears in white on the lower right side of the list.
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If there is an additional page of messages it can be displayed by pushing the ‘CANCEL’ switch. Warning messages are carried over from the previous page.
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The lower screen remains blank so long as all engine and system operating parameters are normal i.e. N2 speed, fuel flow, oil quantity, pressure and temperature, and engine vibration and details of abnormal engine.
EICAS SECONDARY DISPLAY
Status mode
This mode is primarily for use during preparation of the aircraft for flight and shows the status of aircraft systems and their readiness for flight. The information is allied to the aircraft minimum equipment list. The display appears on the lower screen of the EICAS and shows flying control surface positions in analogue format, with system status information in digital message format. The quantity of information available is too great for a single display and is available by selecting successive `pages'. The number of the page being viewed is displayed on the screen.
EICAS STATUS MODE DISPLAY
Maintenance mode
This mode is available to maintenance engineers for diagnosis of operating faults. It contains records of engine and system operating conditions and is only available with the aircraft on the ground. A separate control panel is provided for the display of maintenance data.
EICAS MAINTENANCE PANEL
Example of EICAS maintenance display
EICAS MAINTENANCE DISPLAY
Display select panel
This panel is used to select the type of EICAS display required and is usually situated on the centre console adjacent to the display screens.
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The function of the various controls is as follows:
Display push buttons
When the engine display push button is depressed secondary information appears on the lower screen. Depression of the status push button selects the status mode referred to above.
Event record push button
Engine or system malfunctions in flight are recorded automatically and stored in the EICAS computer memory. Should the flight crew have reason to suspect that a transient fault has occurred, depression of the event record push button will highlight relevant data in the computer stored records for subsequent investigation by maintenance personnel. This latter is known as a manual event.
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Computer rotary switch
This is used to select the in-use computer of the system. In the AUTO position the left computer will normally be in use; switching to the right computer will occur automatically in the event of failure. The LEFT or RIGHT positions are used for manual selection of the in-use computer.
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Brightness control
This is a dual rotary switch. The inner knob controls display intensity and the outer knob controls the brightness balance between the two displays.
Thrust reference setting
This is also a dual rotary switch. The outer knob is used to select an engine and the inner knob is pulled and rotated to position a cursor on the EPR or N1 circular scale.
Maximum indicator reset
If a measured parameter, such as engine oil temperature, exceeds a preset limit an alert will appear on the EICAS display. The maximum indicator reset push button is depressed to clear the alert when the excess condition has been rectified.
EICAS DISPLAY SELECT PANEL
System failures
In the event of failure of one computer, the standby computer will take over either automatically or by pilot selection.
If the lower display unit should fail when secondary information is being displayed on it, an amber alert message appears at the top left of the upper display unit, and the information is transferred to it
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The format of this display is referred to as ‘compact’, and it may be removed by pressing the ‘ENGINE’ switch on the display select panel.
Failure of a display unit causes the function of the panel ‘STATUS’ switch to be inhibited so that the status page format cannot be displayed.
EICAS COMPACT DISPLAY
Should both display screens fail, a standby engine indicator displays essential engine performance data in a liquid crystal diode (LCD) display.
The indicator has a two-position control switch. With this switch in the AUTO position the standby indicator is functioning, but does not display any data unless the CRT displays are not functioning. With the switch in the ON position the unit displays continuously. The test switch has three positions and is used to test the alternative power supplies to the indicator.
STANDBY ENGINE INDICATOR
Failure of the display select panel is indicated on the upper EICAS screen, which continues to display primary engine information. Secondary information still automatically appears on the lower screen, but the panel control switches are inoperative.
Electronic centralised aircraft monitoring (ECAM)
It is principally an aircraft systems display medium, with primary engine information displayed on traditional instruments. The ECAM display screens are mounted side-by-side and both are in use continuously. The left screen displays information covering systems status, warnings and correc- tive actions required in check list format. The right screen shows associated information in analogue displays.
ECAM BLOCK DIAGRAM
Control panel
The ECAM control panel consist of the following.
The left and right display control knobs are for switching on the displays and adjusting the display brightness.
The functions of the various push button switches are as follows:
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SGU select - In normal operation of the system both symbol generator units (SGUs) are functional. In the event of a fault being detected by an SGU self-test circuitry, a fault caption is illuminated on the appropriate switch. Releasing the switch isolates the affected SGU and extinguishes the fault caption, illuminating the OFF caption in its place.
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Clear (CLR) - This is a clear switch, which will illuminate whenever a warning or status message appears on the left screen. Depressing the switch clears the message.
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Status (STS) - Depressing this switch allows manual selection of aircraft system status displays, provided that there is no warning message displayed.
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Recall (RCL) - If a warning message is cleared whilst its associated failure condition is still existent, it may be recalled by depressing the RCL push button.
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Synoptic displays - Synoptic diagrams of each of the 12 aircraft systems are called up on the right screen, provided that there is no warning message displayed, by depressing the appropriate synoptic display switch.
ECAM CONTROL PANEL
Operating modes
The system has four operating modes,
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NORMAL
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ADVISORY
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FAILURE
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MANUAL
Apart from the MANUAL mode, the display modes are automatically selected.
Status messages, which are also displayed on the left-hand display unit, provide the flight crew with an operational summary of the aircraft’s condition, possible downgrading of autoland capability, and as far as possible, indications of the aircraft status following all failures except those that do not affect the flight.
ECAM ADVISORY DISPLAY
Failure Mode
This mode takes precedence over all others and is automatically selected by the ECAM system in the event of normal operating parameters being exceeded in any of the aircraft systems.
An appropriate warning message appears on the left screen, accompanied by an aural alert. Below this message, the corrective actions required by the flight deck crew are listed.
On the right screen a diagrammatic display of the affected system illustrates the fault. When the corrective action has been taken the displays change to illustrate this.
In the example shown the No. 2 generator frequency is outside permitted limits and disconnection of the constant speed drive is called for, with the situation displayed pictorially on the right screen. When the corrective action has been taken, the left screen display changes to show that No. 2 generator is disconnected and the right screen display shows the new status of the a.c. electrical system.
FAILURE MODE DISPLAY BEFORE CORRECTIVE ACTION
FAILURE MODE DISPLAY AFTER CORRECTIVE ACTION
Manual Mode
Provided that there are no warning messages displayed on the left screen, diagrams related to the aircraft systems can be called up on the right screen by depressing any of the synoptic push buttons on the control panel.
