Electronic Flight Instrument Systems (EFIS) Explained

 How EFIS Transformed the Modern Flight Deck

Description: 

Explore Flight Instrument Systems (EFIS): architecture, PFD/ND operation, redundancy, failures, safety, and future flight-deck technology.

 Introduction

Electronic Flight Instrument Systems, or EFIS, replace many traditional electromechanical flight instruments with electronically generated displays.

In a typical modern aircraft, the Primary Flight Display (PFD) combines attitude, airspeed, altitude, vertical speed, heading, navigation guidance, and flight-director information. A Navigation Display (ND) or multifunction display presents the aircraft’s route, navigation aids, weather, traffic, terrain, and other information depending on aircraft configuration.

But EFIS is much more than a screen.

Behind the displays is an interconnected architecture of air-data systems, inertial or attitude-heading sensors, navigation receivers, flight-management computers, display processors, data buses, control panels, electrical power supplies, and failure-monitoring systems.

One of the most important operational principles is this:

A functioning display does not necessarily mean that the data being displayed is correct.

Pilots therefore need to understand the difference between a display failure, a processing failure, and a sensor or data-source failure.

Modern EFIS designs use redundancy, source comparison, reversionary display modes, standby flight instruments, alerting, and carefully designed human-machine interfaces to maintain flight information when individual components fail. EASA training material specifically addresses display-unit failures, symbol-generator failures, reversion, and standby instrumentation as essential EFIS knowledge.

Executive Summary

Electronic Flight Instrument Systems represent one of the most important changes in aircraft cockpit design since the development of reliable flight instrumentation.

Traditional flight decks required pilots to interpret numerous individual mechanical instruments. Modern EFIS technology integrates large quantities of aircraft data into organized electronic presentations that allow pilots to understand aircraft attitude, energy state, navigation, trajectory, automation status, terrain, traffic, and weather much more efficiently.

The transition began during the development of advanced electronic cockpits in the 1970s and 1980s. NASA research contributed significantly to the concept of replacing conventional instruments with integrated electronic displays, and the technology subsequently became standard across commercial, military, business, and increasingly general aviation aircraft.

Modern EFIS installations typically center on the Primary Flight Display and Navigation Display or Multifunction Display, but these displays depend on numerous external systems. Air-data computers provide speed and altitude information. Inertial or attitude-heading systems supply attitude and heading. Flight-management systems provide navigation and trajectory data. Weather radar, terrain-awareness systems, surveillance systems, and other avionics can contribute additional information.

The FAA describes a PFD as the primary electronic presentation of essential flight parameters including altitude, airspeed, heading, and attitude.

The greatest advantage of EFIS is not simply that electronic displays replaced mechanical gauges. Its real contribution is information integration.

A modern pilot can see not only where the aircraft is and how it is moving, but also where it is expected to go, what the automation is commanding, what threats exist around the aircraft, and whether the aircraft is deviating from the intended flight path.

That capability brings equally important responsibilities. Pilots must monitor automation modes, recognize unreliable data, understand display reversion, know their standby references, and resist assuming that a highly convincing electronic presentation must automatically be correct.

Table of Contents

1. What Is an Electronic Flight Instrument System?
2. How EFIS Evolved
3. EFIS Components and Architecture
4. How an EFIS Works
5. Primary Flight Display
6. Navigation and Multifunction Displays
7. EFIS Integration With Other Aircraft Systems
8. Redundancy, Reversion, and Failure Management
9. Operational Functions and Advantages
10. Limitations and Human-Factors Challenges
11. Advanced EFIS Technology
12. Lesser-Known Engineering Facts
13. Pilot’s Perspective
14. Maintenance Engineer’s Perspective
15. Accident Lessons Learned
16. In Summary
17. Terminology
18. Common Misconceptions
19. Main Points
20. Frequently Asked Questions
21. Future Outlook
22. Conclusion
23. Discussion Questions

1. What Is an Electronic Flight Instrument System?

An Electronic Flight Instrument System (EFIS) is an aircraft avionics system that electronically processes and displays flight and navigation information to the flight crew.

Instead of requiring separate mechanical instruments for attitude, airspeed, altitude, vertical speed, heading, and navigation, EFIS can combine these parameters into integrated electronic presentations.

The two displays most closely associated with traditional EFIS architecture are:

• Primary Flight Display — PFD
• Navigation Display — ND

Earlier generations often used the terms:

• Electronic Attitude Director Indicator — EADI
• Electronic Horizontal Situation Indicator — EHSI

The modern PFD is effectively the evolutionary successor to the EADI, while the ND evolved from electronic horizontal-situation presentations.

FAA guidance describes electronic flight displays as providing pilots with highly integrated instrumentation for instrument flying, while a PFD typically combines altitude, airspeed, vertical velocity, attitude, heading, and associated trend or guidance information.

EFIS Is Not Exactly the Same as a Glass Cockpit

The two terms are frequently used interchangeably, but technically they describe different ideas.

EFIS primarily refers to electronic presentation of flight and navigation instrumentation.

A glass cockpit is the broader flight-deck concept in which multiple traditional instruments and system indicators are replaced by electronic displays.

For example, a modern glass cockpit may include:

• PFDs
• Navigation displays
• Multifunction displays
• Engine displays
• Crew-alerting displays
• Electronic checklists
• System synoptic pages
• Flight-management interfaces
• Electronic charts
• Surveillance displays

NASA describes the Boeing 777 glass-cockpit environment as using electronic PFD, ND, EICAS, and control-display functions.

Therefore:

EFIS is one of the foundational technologies that made the modern glass cockpit possible.

2. How EFIS Evolved

From the “Six-Pack” to Integrated Displays

For decades, aircraft flight information was presented using individual electromechanical instruments.

A typical arrangement included:

• Airspeed indicator
• Attitude indicator
• Altimeter
• Turn coordinator or turn-and-bank indicator
• Heading indicator
• Vertical-speed indicator

Each instrument provided a particular piece of information.

The pilot mentally integrated those individual indications into an understanding of the aircraft’s three-dimensional flight condition.

Electronic displays changed this relationship dramatically.

Instead of forcing the pilot to construct a mental picture from numerous gauges, avionics engineers could present an increasingly integrated representation of the airplane’s state and intended trajectory.

NASA and the Glass-Cockpit Era

During the 1970s and 1980s, NASA conducted important research into advanced cockpit configurations using electronic displays.

NASA notes that these developments replaced numerous traditional gauges with digital displays designed to present information more efficiently and provide crews with a more integrated picture of the aircraft’s situation.

By the early generation of highly automated commercial aircraft, cathode-ray-tube displays had begun replacing conventional instruments.

Later developments progressed through:

Electromechanical instruments → CRT electronic displays → LCD displays → large-format configurable displays → touchscreen and integrated flight decks

Modern Airbus aircraft illustrate this evolution clearly. The A350 cockpit uses six large LCD screens to provide extensive flight and system information, while modernized Airbus installations continue moving toward higher-resolution display technology.

3. EFIS Components and Architecture

                              Click The Image for Details

An EFIS architecture can be understood as five major layers:

Sensors → Data processing → Avionics network → Display processing → Pilot interface

Exact architecture varies significantly between aircraft.

3.1 Sensor and Data Sources

An EFIS does not normally measure most flight parameters itself.

Instead, it receives information from other aircraft systems.

Typical inputs include:

Air-Data System

The air-data system processes information derived from sources such as:

• Pitot pressure
• Static pressure
• Total air temperature

It can provide parameters including:

• Indicated airspeed
• Mach number
• Pressure altitude
• Vertical speed
• True airspeed
• Air temperature

Depending on aircraft generation, this function may be performed by an Air Data Computer (ADC) or integrated Air Data Inertial Reference Unit (ADIRU).

Attitude and Heading Sources

Aircraft attitude and heading information may come from:

• Attitude and Heading Reference System — AHRS
• Inertial Reference System — IRS
• Inertial Reference Unit — IRU
• Integrated air-data/inertial systems

These systems provide information such as:

• Pitch
• Roll
• Heading
• Attitude rates
• Acceleration
• Aircraft orientation

Navigation Sources

Navigation information may originate from:

• GNSS/GPS
• VOR
• DME
• ILS
• FMS
• Inertial navigation
• Radio-navigation receivers

Surveillance and Hazard Systems

Additional information may come from:

• TCAS/ACAS
• ADS-B
• Weather radar
• TAWS/EGPWS
• Radar altimeter
• Windshear-detection systems

3.2 Display Processing

Sensor information cannot simply be sent directly to the screen as raw numbers.

It must be validated, converted, organized, and transformed into graphical symbols.

Earlier EFIS architectures commonly used dedicated symbol generators.

A symbol generator receives aircraft information and converts it into the electronic graphical commands needed to create the display.

Modern integrated avionics may distribute these functions among:

• Display computers
• Graphics processors
• Integrated modular avionics applications
• Display-processing modules

EASA’s aircrew knowledge standards specifically identify EFIS components such as:

• Control panel
• Display units
• Symbol generator
• Remote light sensor

They also require pilots to understand the operational difference between a symbol-generator failure and a display-unit failure.

3.3 Avionics Data Networks

Modern aircraft contain many computers that must exchange data.

Depending on aircraft generation and architecture, interfaces may include technologies such as:

• ARINC 429
• ARINC 629
• ARINC 664-based networks
• Other certified digital avionics buses

The EFIS therefore functions as part of a much larger avionics ecosystem rather than as an isolated instrument.

Modern open architectures go even further. GE Aerospace, for example, describes avionics architectures integrating computing systems, controls and displays, digital backbone networks, flight-management systems, navigation, and interface controllers.

4. How an EFIS Works

Consider an aircraft climbing after departure.

The process can be visualized in seven stages.

Step 1 — Sensors Measure the Aircraft State

The pitot-static system senses aerodynamic pressures.

Inertial sensors determine attitude and motion.

GNSS and navigation systems determine position.

Other aircraft systems continuously generate additional data.

Step 2 — Dedicated Computers Calculate Parameters

Air-data computers convert pressure information into useful flight parameters.

Inertial systems calculate aircraft attitude and heading.

The FMS determines navigation guidance and intended flight path.

Step 3 — Information Is Checked and Distributed

Avionics computers exchange information through aircraft data buses.

Redundant systems may compare data between independent sources.

Depending on aircraft design, inconsistent information can produce:

• Flags
• Comparator warnings
• Changed display colors
• Alert messages
• Removal of unreliable information

Step 4 — Display Processing Creates the Presentation

The display system converts numerical aircraft data into graphical information.

For example:

Pitch + roll data → artificial horizon

Air-data information → airspeed and altitude tapes

FMS route data → navigation route line

Flight-guidance commands → flight-director bars

Step 5 — Information Appears on the PFD and ND

The pilot receives an organized presentation instead of dozens of unrelated numbers.

Step 6 — The Pilot Interacts With the System

The crew may change:

• Barometric setting
• Navigation-display range
• Navigation-display mode
• Map overlays
• Minimums
• Navigation source
• Display configuration

EASA identifies these types of selections as typical EFIS control-panel functions.

Step 7 — Reversion Occurs if Required

If one display or processing channel becomes unavailable, another display may be configured to show essential information.

This is known as display reversion or reversionary operation.

5. The Primary Flight Display

PDF                                   ND

The PFD is normally positioned directly in the pilot’s primary field of view.

FAA certification guidance describes the PFD as the primary presentation of essential parameters including:

• Altitude
• Airspeed
• Heading
• Attitude

and notes that it can also provide information relevant to guidance and fundamental control of the aircraft.

A modern transport-aircraft PFD commonly includes:

Attitude

The central artificial horizon provides pitch and bank information.

Airspeed

A vertical tape normally shows:

• Current indicated airspeed
• Selected speed
• Speed trend
• Operational speed limits
• Configuration-related speed information

Altitude

Another tape typically displays:

• Current altitude
• Selected altitude
• Altitude trend
• Barometric setting

Vertical Speed

Vertical speed may appear alongside the altitude presentation.

Heading or Track

Heading information is normally displayed at the bottom of the attitude presentation.

Flight Director

Flight-director commands tell the pilot where the flight-guidance system wants the aircraft to go.

Flight Mode Annunciator

One of the most operationally important areas of the PFD is the Flight Mode Annunciator (FMA).

It tells the pilot what the autoflight system is actually doing.

This is critical because:

What the pilot selected and what the aircraft actually captured or engaged are not always the same thing.

For automated-aircraft operations, disciplined FMA monitoring is therefore essential.

6. Navigation Display and Multifunction Displays

If the PFD answers:

“What is the aircraft doing?”

the Navigation Display largely answers:

“Where is the aircraft going?”

Depending on the aircraft, an ND can display:

• Current position
• Planned FMS route
• Active waypoint
• Heading
• Track
• Distance
• Groundspeed
• VOR/DME information
• Weather radar
• Terrain
• Traffic
• Airports
• Navigation aids
• Airspace or constraints

Modern multifunction displays can go considerably further.

Garmin’s G5000 architecture, for example, can provide split-screen presentation of maps, charts, checklists, terrain-awareness information, traffic, flight-plan information, weather, and other functions.

The important engineering principle is that display hardware and display function are increasingly separated.

A physical screen does not necessarily have to remain permanently assigned to only one function.

That makes modern flight decks more flexible and improves failure-management capability.

7. EFIS Integration With Other Aircraft Systems

One reason modern EFIS installations are powerful is that they integrate information originating across the aircraft.

Flight Management System

The FMS supplies information including:

• Desired track
• Waypoints
• Navigation guidance
• Lateral course deviation
• Flight-plan information

FAA guidance notes that FMS outputs can feed flight-guidance displays as well as autopilot and flight-director functions.

Automatic Flight Control System

EFIS allows the crew to observe:

• Flight-director commands
• Autopilot modes
• Autothrottle modes
• Selected targets
• Captured modes

The displays therefore become an important part of the pilot’s interface with aircraft automation.

Weather Radar

Weather-radar information can be superimposed on navigation displays, allowing pilots to compare hazardous precipitation with the planned flight path.

TCAS/ACAS

Traffic symbols and resolution-advisory guidance can be integrated into cockpit displays.

TAWS

Terrain-awareness information can appear graphically relative to aircraft position and altitude.

Engine and Aircraft Systems

Many modern integrated cockpits also display:

• Engine parameters
• Fuel systems
• Electrical systems
• Hydraulics
• Flight controls
• Air conditioning
• Doors
• Alerts

However, systems such as EICAS and ECAM should not automatically be treated as synonyms for EFIS. They are separate but closely integrated electronic display and alerting functions within the broader glass-cockpit architecture.

8. Redundancy, Reversion, and Failure Management

Redundancy is one of the most important EFIS design principles.

A modern transport aircraft cannot depend on one screen, one sensor, or one computer for essential flight information.

Independent Data Sources

Depending on aircraft architecture, captain and first-officer displays may normally receive data from separate sources.

If disagreement occurs, pilots may receive a comparator or source warning.

An ICAO-hosted investigation report describing a transport EFIS installation notes that each pilot had a PFD and MFD, with normally independent inertial-reference sources and selectable alternate sources when required.

Display Reversion

If a display unit fails, critical information may be transferred to another functioning screen.

Modern Garmin installations, for example, allow flight displays to operate in reversionary PFD/MFD configurations.

Standby Instruments

Even highly integrated aircraft retain independent standby flight information.

Depending on design, this may be a traditional standby group or an Integrated Standby Instrument System — ISIS/ISFD.

The standby system may provide:

• Attitude
• Airspeed
• Altitude
• Heading
• ILS information

EASA training requirements specifically emphasize the importance of standby instruments following loss of normal EFIS displays.

9. Operational Functions and Applications

Modern EFIS supports virtually every phase of flight.

Departure

Pilots can monitor:

• Airspeed acceleration
• Flight-director commands
• Initial altitude
• Lateral navigation
• Autoflight modes

Climb and Cruise

The EFIS supports:

• Route monitoring
• Weather avoidance
• Traffic awareness
• Altitude monitoring
• Aircraft energy management

Approach

Information becomes increasingly concentrated.

Pilots may monitor:

• Localizer or lateral guidance
• Glidepath or glideslope
• Minimums
• Selected altitude
• Flight modes
• Airspeed
• Radio altitude
• Runway or approach symbology

Go-Around

Flight-director and mode-annunciation information becomes particularly important because aircraft configuration and automation modes can change rapidly.

10. Advantages of Electronic Flight Instrument Systems

Better Information Integration

EFIS places related information together.

This reduces the amount of mental reconstruction required compared with scanning numerous independent instruments.

Improved Situational Awareness

Navigation, terrain, weather, and traffic can be presented relative to the aircraft and planned route.

Reduced Instrument-Panel Complexity

Multiple mechanical indicators can be replaced by configurable electronic displays.

Failure Reversion

A functioning display may be reassigned to replace a failed unit.

Improved Upgrade Potential

Software-defined and open architectures can support additional functions without completely redesigning the cockpit.

Collins Aerospace describes integrated flight-deck architectures as allowing extensive aircraft-system integration and future capability growth.

Better Presentation of Trends

Electronic displays can show where parameters are going rather than only where they are now.

Speed and altitude trend indications are good examples.

11. Limitations and Human-Factors Challenges

More information does not automatically mean better awareness.

NASA research into glass-cockpit and automation interaction has identified benefits in precision, efficiency, safety, and functionality, while also emphasizing challenges involving complexity, monitoring, automation modes, crew coordination, workload, and training.

Data-Source Errors

Perhaps the most important limitation is that:

The display can operate perfectly while displaying incorrect input data.

An erroneous air-data source, inertial source, navigation database, or other input can produce convincing but misleading information.

Mode Awareness

The PFD can tell the pilot what automation mode is active—but the pilot must actually monitor it.

Information Overload

Too much information or poorly selected overlays can increase clutter.

Electrical Dependency

Electronic displays require reliable electrical power.

Redundancy and standby-power systems are therefore fundamental design considerations.

Software and Configuration Complexity

Integrated systems contain substantial certified software and configuration data.

Troubleshooting can consequently involve much more than replacing a physical display.

Skill Degradation

Highly capable electronic flight decks can tempt pilots to become dependent on automation.

Sound instrument-flying fundamentals remain essential.

12. Advanced Technology and Lesser-Known Facts

12.1 Synthetic Vision

Synthetic Vision Systems create a computer-generated representation of terrain and other environmental features using aircraft position and databases.

Synthetic terrain may appear behind conventional PFD symbology.

Honeywell’s current Primus Epic family, for example, supports synthetic-vision and advanced situational-awareness functions.

12.2 Touchscreen Flight Decks

Touchscreens are moving deeper into certificated flight decks.

Garmin’s G5000 PRIME incorporates large touchscreen primary displays and secondary touchscreen displays, along with increased computing and network capability.

Airbus has also delivered A350 aircraft incorporating touchscreen cockpit-display capability.

12.3 Large Configurable Displays

Modern flight decks increasingly use fewer but larger displays.

The Boeing 787, for example, uses large LCD flight-deck displays and dual head-up displays to support flight information and situational awareness.

12.4 EFIS Certification Is About More Than Image Quality

The display must satisfy requirements involving much more than resolution.

EASA ETSO-C209 references minimum performance standards covering both electronic flight-instrument display functions and multipurpose electronic displays.

Certification considerations include matters such as:

• Display integrity
• Visibility
• Failure behavior
• Environmental performance
• Human factors
• Function criticality

12.5 The Screen Is Often Not the Most Important Part

The most expensive or safety-critical problem during an apparent “display malfunction” may exist somewhere upstream.

Possible causes include:

• Sensor failure
• Data-bus failure
• Processing failure
• Power-supply failure
• Configuration problem
• Cooling problem
• Display-unit failure

This is why maintenance troubleshooting follows the data chain, not merely the visible symptom.

12.6 Automatic Brightness Control Matters

Remote light sensors may form part of EFIS installations.

This sounds minor, but cockpit information must remain readable across extreme lighting environments—from bright sunlight to a dark flight deck at night.

12.7 Head-Up Displays Are Related but Separate

A HUD may receive much of the same aircraft information used by the EFIS, but certification standards can treat head-up display systems separately from conventional head-down EFIS displays.

EASA’s ETSO-C209 explicitly notes that its EFIS display standard does not cover head-up displays.

13. What About Artificial Intelligence?

Artificial intelligence should not be confused with conventional EFIS processing.

Today’s primary certified flight displays predominantly depend on deterministic, rigorously verified avionics functions rather than unconstrained AI decision-making.

However, future flight decks are moving toward:

• Better automated information management
• More sophisticated alert prioritization
• Advanced graphics
• Increased connectivity
• Open computing architectures
• Assisted trajectory management
• Greater autonomy in selected applications

GE Aerospace, for example, is developing avionics and open architectures intended to support future autonomous and advanced aviation applications.

The major challenge will not simply be whether AI can generate useful information.

The more important aviation questions are:

Can it be certified?

Can its behavior be understood?

Can its failure modes be managed?

Can pilots maintain appropriate authority and situational awareness?

For safety-critical displays, explainability, deterministic behavior where required, integrity assurance, and human-factors engineering will remain central considerations.

14. Pilot’s Perspective

For pilots, the most important EFIS skill is not learning where information appears during normal operation.

It is understanding what that information means and where it came from.

An experienced pilot should continually be asking:

• What is my aircraft doing?
• What is the automation doing?
• What will it do next?
• Which source is supplying this information?
• Does the indication make sense?
• Do independent sources agree?

Consider an unreliable-airspeed event.

If the displayed speed suddenly becomes unreasonable, simply staring harder at the PFD will not solve the problem.

The pilot must evaluate:

• Pitch attitude
• Thrust
• Other airspeed sources
• Standby instruments
• Aircraft configuration
• Warnings
• Cross-cockpit comparison

The lesson is fundamental:

EFIS improves the pilot’s ability to interpret information, but it never eliminates the need to validate that information.

15. Maintenance Engineer’s Perspective

For avionics technicians and maintenance engineers, EFIS troubleshooting is fundamentally an exercise in system architecture.

Suppose a captain’s PFD loses attitude information.

Possible causes include:

• Display-unit hardware
• Graphics processor
• Symbol generator
• Data bus
• Connector
• Wiring
• Power supply
• IRS/AHRS
• Cooling system
• Software configuration

Replacing the screen without understanding the failure path could leave the actual fault untouched.

Maintenance therefore requires:

1. Reading crew reports carefully.
2. Reviewing fault messages and maintenance-computer data.
3. Identifying which functions failed.
4. Determining whether multiple displays share the failure.
5. Identifying the common upstream source.
6. Checking applicable AMM fault-isolation procedures.
7. Performing required operational tests.

Integrated avionics make maintenance more capable because faults can often be recorded automatically, but they also increase the importance of configuration management and disciplined troubleshooting.

16. Accident Lessons Learned

EFIS itself should not be blamed simply because an accident aircraft had electronic displays.

The more useful approach is to examine what accidents teach us about information, automation, sensing, and human-machine interaction.

Birgenair Flight 301 — Trusting Bad Data

The Boeing 757 involved in Birgenair Flight 301 experienced erroneous airspeed information associated with a blocked pitot source.

The FAA’s Lessons Learned material explains that conflicting airspeed indications developed after departure and that erroneous airspeed information interacted with automation as the situation deteriorated.

The deeper EFIS lesson is:

A perfectly functioning display may faithfully present incorrect sensor data.

Pilots must distinguish:

Display failure

from

Data failure.

Cross-checking independent sources is therefore essential.

Air Inter Flight 148 — Mode Awareness

The Air Inter A320 accident near Strasbourg highlighted another modern-flight-deck problem: automation mode confusion.

FAA Lessons Learned material describes how the investigation considered confusion between vertical-speed and flight-path-angle selections, together with workload, mode awareness, and crew monitoring.

The broader lesson is not that electronic displays are unsafe.

It is that:

Automation must be positively monitored through the flight-mode information presented to the crew.

The safest cockpit philosophy remains:

Select it. Verify it. Monitor it

17. In Summary 

System: Electronic Flight Instrument System — EFIS

Primary purpose: Present essential flight and navigation information electronically in an integrated, rapidly interpretable form.

Historical emergence: Advanced electronic cockpit concepts developed during the 1970s and early 1980s, followed by widespread adoption in transport aircraft during the glass-cockpit era.

Typical manufacturers and suppliers: Honeywell, Collins Aerospace, Garmin, Thales, GE Aerospace and other certified avionics manufacturers depending on aircraft program.

Typical aircraft: Modern commercial airliners, business jets, regional aircraft, helicopters, military aircraft, and increasingly general aviation aircraft.

Major components: Display units, display processors or symbol-generation functions, EFIS controls, avionics data interfaces, sensor/data sources, electrical supplies, brightness controls, and reversionary/standby equipment.

Primary displays: PFD and ND/MFD.

Typical inputs: Air data, attitude/heading, GNSS, FMS, navigation radios, weather radar, TCAS/ACAS, TAWS and other aircraft computers.

Key safety feature: Multiple data sources, redundant processing, display reversion, comparator monitoring, alerting, and independent standby information.

18. Terminology

EFIS — Electronic Flight Instrument System: Electronic system used to display primary flight and navigation information.

EFD — Electronic Flight Display: General term for an electronic cockpit display.

PFD — Primary Flight Display: Main pilot display for attitude, airspeed, altitude, heading, vertical information, flight guidance, and related primary information.

ND — Navigation Display: Display providing navigation, route, position, weather, traffic, and other situational information depending on configuration.

MFD — Multifunction Display: Configurable display capable of presenting several types of information.

EADI — Electronic Attitude Director Indicator: Earlier electronic presentation combining attitude and flight-director information.

EHSI — Electronic Horizontal Situation Indicator: Earlier electronic navigation presentation from which modern navigation displays evolved.

FMA — Flight Mode Annunciator: Area indicating active and armed autoflight modes.

ADC — Air Data Computer: Computes flight parameters from air-pressure and temperature inputs.

AHRS — Attitude and Heading Reference System: Electronic system that provides attitude and heading information.

IRS — Inertial Reference System: Inertial system providing attitude, heading, motion and, depending on architecture, navigation information.

ADIRU — Air Data Inertial Reference Unit: Integrated unit combining air-data and inertial-reference functions.

FMS — Flight Management System: Computes and manages flight planning, navigation, performance and trajectory information.

TCAS/ACAS — Traffic Collision Avoidance System/Airborne Collision Avoidance System: Surveillance and collision-avoidance system providing traffic information and, when required, resolution advisories.

TAWS — Terrain Awareness and Warning System: Provides terrain-related situational awareness and warnings.

Symbol Generator: Processing function that converts aircraft data into graphical symbols for electronic displays.

Reversionary Mode: Configuration that transfers important information to another available display following a failure.

ISFD/ISIS: Integrated standby flight display/instrument system providing independent backup flight information.

19. Common Misconceptions

Misconception 1: “EFIS is just a digital instrument panel.”

Reality: The display is only one part of a network involving sensors, computers, communication buses, controls, power sources, and redundancy.

Misconception 2: “If the screen works, the information must be correct.”

Reality: A display can work perfectly while receiving incorrect information from an upstream sensor.

Misconception 3: “A glass cockpit and EFIS are exactly the same.”

Reality: EFIS specifically concerns electronic flight and navigation instrumentation. Glass cockpit is a broader description encompassing additional electronic systems and displays.

Misconception 4: “Modern aircraft no longer require standby instruments.”

Reality: Independent standby flight information remains an essential part of failure management.

Misconception 5: “Automation reduces the need for instrument scanning.”

Reality: Automation changes the scan. Pilots must monitor flight path, primary parameters, navigation and especially automation-mode status.

20. Main points

• EFIS electronically presents primary flight and navigation information.
• The PFD integrates essential parameters such as attitude, airspeed, altitude, heading, vertical information, and flight guidance.
• The ND/MFD provides route and situational information.
• EFIS receives information from multiple aircraft systems rather than measuring most parameters itself.
• A display failure and a sensor/data-source failure are fundamentally different events.
• Redundancy, source comparison, display reversion, and standby instrumentation are critical safety features.
• Modern large-format displays can perform multiple functions instead of remaining permanently assigned to one role.
• Effective automation management requires disciplined monitoring of flight-mode annunciations.
• Synthetic vision, touchscreen interfaces, and open avionics architectures are expanding display capability.
• AI may influence future cockpit technology, but certification, predictability, integrity, and human oversight remain fundamental.
• EFIS improves situational awareness only when pilots understand both the information displayed and the architecture producing it.

21. Frequently Asked Questions

1. What does EFIS mean in aviation?

EFIS means Electronic Flight Instrument System. It electronically displays essential flight and navigation information to the flight crew.

2. What are the main EFIS displays?

Traditionally, the principal EFIS displays are the Primary Flight Display and Navigation Display. Modern systems may use multifunction or reconfigurable displays.

3. What does the PFD show?

The PFD normally includes attitude, indicated airspeed, altitude, heading or track, vertical-speed information, flight-director guidance, navigation deviations, and flight-mode information.

4. What does the Navigation Display show?

Depending on aircraft configuration, it can show the planned flight route, aircraft position, waypoints, navigation aids, weather radar, traffic, terrain, and other situational information.

5. Is EFIS the same as the FMS?

No.

The FMS computes and manages navigation and flight-plan information.

The EFIS displays information to the pilot.

FMS outputs are among the many inputs that may appear on EFIS displays.

6. Is EICAS part of EFIS?

They are closely integrated in many glass cockpits but should not automatically be treated as identical systems.

EICAS is primarily an engine-indication and crew-alerting system.

EFIS traditionally refers to electronic flight and navigation instrumentation.

7. What happens if a PFD fails?

The exact procedure depends on aircraft type.

Many aircraft allow essential PFD information to be transferred to another screen, while independent standby instruments provide additional backup.

Pilots must follow the applicable QRH/FCOM procedure.

8. Can an EFIS display incorrect information?

Yes.

If a sensor or upstream data source provides incorrect information, a functioning display may present that information unless the system detects the disagreement or invalidity.

9. What is a symbol generator?

In traditional EFIS architectures, a symbol generator receives aircraft data and generates the graphical information presented on electronic displays.

Modern integrated systems may distribute equivalent functions among different processing modules.

10. Are touchscreen displays replacing conventional cockpit controls?

Touchscreens are increasingly used for some aircraft functions, but implementation varies considerably.

Physical controls remain valuable for particular critical, frequently used, or time-sensitive functions depending on aircraft design and certification philosophy.

22. Future of Electronic Flight Instrument Systems

The future of EFIS will probably be defined less by simply increasing screen size and more by improving information management.

Emerging developments include:

• Larger configurable displays
• Touch interfaces
• Synthetic vision
• Enhanced-vision integration
• Advanced head-up guidance
• More capable graphics processors
• Open avionics architectures
• High-speed aircraft networks
• Increased connectivity
• Advanced trajectory information
• Improved weather presentation
• More sophisticated alert management
• Greater integration with automation

The latest commercial technology already demonstrates that direction.

Garmin introduced its G5000 PRIME architecture with high-resolution touchscreen primary displays, increased processing capability, greater memory, high-speed connectivity, and flexible display layouts.

Airbus is also modernizing earlier A320-family cockpit displays through its EEIS2 program using high-resolution LCD technology and a foundation designed for further avionics upgrades.

The engineering objective remains unchanged:

Give the flight crew the right information, in the right form, at the right time—without creating unnecessary complexity.

23. Conclusion

Electronic Flight Instrument Systems fundamentally changed how pilots interact with aircraft.

The transition from mechanical instruments to integrated electronic displays did much more than modernize cockpit appearance. It changed the way flight information is collected, processed, integrated, monitored, and understood.

Today’s PFDs and navigation displays allow a pilot to observe aircraft attitude, energy state, trajectory, navigation, automation, weather, terrain, and traffic with a level of integration unavailable to earlier generations.

But EFIS technology also teaches an important aviation principle:

Information is only as reliable as the chain that creates it.

A screen depends on processors.

Processors depend on data networks.

Data networks depend on sensors.

And the entire system ultimately depends on trained pilots recognizing whether the information makes sense.

The safest flight crews therefore do more than read electronic displays.

They understand them.

As flight decks move toward synthetic vision, touchscreen interfaces, open architectures, advanced automation, and increasingly intelligent systems, that understanding will become even more important.

The future cockpit may contain fewer individual instruments—but the pilot’s responsibility to understand the aircraft behind the display will never disappear.

Discussion Questions

1. Have you operated, maintained, taught, or studied an Electronic Flight Instrument System?
2. Which aircraft do you think uses electronic flight displays most effectively?
3. Do you prefer highly configurable displays or more standardized fixed display layouts?
4. What future improvements would you like to see in PFD and navigation-display technology?
5. How should manufacturers balance increased automation with pilot situational awareness?
6. Share your experience or questions below.