An electronic flight instrument system (EFIS)
is a flight deck instrument display system located at the flight cockpit in the
lower deck after the windshield. It is powered electronically and produce
digital output.

The electronic display unit system consists of 3
different display units, the Primary Flight Display(PFD), Navigational
Display(ND) and EICAS / ECAM based on the engine
manufacturer. There is one PFD and ND each for the first officer and captain.
However, the EICAS/ECAM are shared between both crews.

 

EFIS installations vary
greatly. A light aircraft might be equipped with one display unit, displayed
flight and navigation data whereas a wide-body aircraft is likely to have six
or more display units.

Purpose of Electronic Flight Instrument System (EFIS)

The purpose of an
Electronic Flight Instrument System (EFIS) in an aircraft is to display output
flight data in a CRT or LCD screen to monitor the progress of the aircraft’s
flight and the correct function of all aircraft’s parts and system. As well as
display essential information to aid the flight crew to operate the aircraft in
a safe and efficient way.

The EFIS units aid
the pilot in controlling of the aircraft and making decision during flight to
the intended destination, by providing the flight information and navigational
information of the flight performance.

Operations
and functions of each unit of EFIS

1.    Air Data Inertial reference unit

The inertial reference unit
is connected to the aircraft sensors all around the aircraft to produce flight
and air data. The sensors include pitot static tube and ring laser gyroscope.
The whole system can be split into 2 units, the air data unit and inertial
reference unit.  In the air data unit,
the pitot static tubes are used with air data modules to convert air pressure
into electrical signal magnitudes to the Inertial reference unit through data
buses. With the calculation of Airspeed, Mach number, temperature and
barometric pressure altitude. The Air Data Inertial reference unit then
compiles the information and process it to send to the next phase to display
the result.

2.    Navigational data

Navigational Data is a common
block of data that gives navigational information to guide the aircraft to
reach the intended destination safely and efficiently through available or
decided routes and communication. Normally, updated every 28 days for
its contents to be current. The data
taken from different sensors and instruments around the aircraft. Such as
weather radars, transponders, and etc. The navigation data consist of the
weather data, instrument landing system data, flight path data, traffic
collision alerting system data, and etc, which aids the aircraft to navigates
properly.

3.    EFIS Control Panel

EFIS control panel helps to
give manual control to the pilot to select the settings and control the
displays by choosing what information to be displayed in the CRT or LCD
displays. They provide the pilots with the controls to the displays such as
brightness, range and mode settings in maps and to show preferred data and to
enter data.  

4.    Primary Flight display (PFD)

A primary flight displays (PFD) is an instrument dedicated to
flight information. It is a representation of “steam gauge”
instruments, combined on one compact display,
to help simplifying the pilot’s workflow and streamlining cockpit layouts. The
flexibility in the system makes it possible to display at any given moment only
the information required for the present flight phase.

5.   
Navigation display (ND)

The
navigation displays (ND) displays navigational and weather information from
multiple systems. The second display on each pilot’s main
instrument panel can now be used for to replace the conventional Horizontal
Situation Indicator (HSI) to a Navigation Display (ND). the aircrew can
overlay different information over a map or chart. The ND overlay information such
as the aircraft’s current route plan, weather information from either on-board
radar or lightning detection sensors or ground-based sensors, restricted
airspace and aircraft traffic. It can be used to view other non-overlay type of
data such as current route plan and calculated overlay-type data such as the
glide radius of the aircraft, the given current location over terrain, winds,
and aircraft speed and altitude. ND can also display information about aircraft
systems, such as fuel and electrical systems and changes the colour or shape of
the data to alert the aircrew of hazardous situations.

Pilots
have five modes of presentation

1)    Instrument Landing
System (ILS) ® Displays course and
localizer deviation.

2)    VHF Omnidirectional
Range(VOR) ® Points to the
selected VOR course.

3)    Navigation(NAV) ® Shows all the necessary information in rose
mode.

4)    ARC ® Limited to forward 90 degrees sector.

5)    PLAN ® Specific to the route visualization. Only
the programmed route is displayed with all the waypoints in flight plan.

6.    EICAS/ ECAM

The Engine
Indications and Crew Alerting System displays information about the aircraft’s
systems, such as its fuel, electrical and engines. EICAS displays are designed
to mimic traditional round gauges while supplying digital readouts of the
parameters. It improves the situational awareness by allowing the aircrew to
view complex information in a graphical format and alerts aircrews to hazardous
situations. Proper care must be taken when designing EICAS to ensure that the
aircrew are always provided with the most important information.

 

7.   
Warning and Caution light

The Warning
alerts are always displayed in red, and also flashes to capture the attention
of the flight crew together with an aural alert. If the attitude or airspeed
display fail, the EFIS loses the system valid signal to the display and scale
markings will be removed as well as the displaying of the associated warning
flags. Cautionary and warning alerts may flash for few seconds before becoming
steady, to draw the flight crews’ attention.

Location and Placement

 

 

References

1.   
En.wikipedia.org. (2018). Electronic flight
instrument system. online Available at:
https://en.wikipedia.org/wiki/Electronic_flight_instrument_system Accessed 15
Jan. 2018.

2.   
Skybrary.aero. (2018). Electronic Flight Instrument
System – SKYbrary Aviation Safety. online Available at:
https://www.skybrary.aero/index.php/Electronic_Flight_Instrument_System
Accessed 15 Jan. 2018.