The EFIS is made up of the Electronic Attitude Direction Indicator (EADI) and the Electronic Horizontal Situation Indicator (EHSI). The EADI is sometimes referred to as the “Primary Flight Display” (PFD) and the EHSI is sometimes referred to as the “NAV DISPLAY” (ND). These are cathode ray tubes, essentially the same as your television screen.

• They are more reliable.

• They allow the crew to display selected information, thereby avoiding screen “CLUTTER” and information overload

• CRT units incorporate a light sensitive device that will automatically adjust display brightness to compensate for varying light levels, such as happens when flying in and out of cloud. The EFIS can display more information than can the conventional ADI/HSI, increasing the crews situational awareness of their vertical and horizontal path in space.

• CRT units use various colours to better inform crews of the modes the aircraft is currently flying in, and which waypoint the aircraft is currently flying toward (ie: the “ACTIVE” waypoint).

• The EFIS reduces the amount of scanning required by the crew. (eg: All information required to fly an ILS can be found on the EADI screen, with no need to cross scan to other instruments).

FULL ILS mode

There are six different EHSI modes which can be set by the crew using the EHSI control panel. In this mini editorial we will be looking at the “FULL ILS” mode.

This mode provides the same 360 degree compass presentation as does a conventional VOR/ILS instrument, and it is oriented HEADING UP.

The “FULL ILS” and “FULL VOR” modes are sometimes referred to as “ROSE MODE”.

Orientation

Like the EXPANDED ILS it is oriented magnetic HEADING UP. Weather radar returns CANNOT be displayed in FULL ILS mode, but can in “EXPANDED ILS” mode.

Aircraft Symbol

Like the conventional VOR/ILS instrument, the aircraft symbol is shown in the centre of the compass rose. It is displayed in white.

ILS selection/distance

The fact that ILS is feeding tracking information to the screen is displayed in green at the bottom left-hand corner of the screen, whilst the distance to that station is in the upper left corner. The ILS frequency is displayed in green in the bottom right-hand corner. Inbound course of the localiser is 050 magnetic. Distance to the ILS is 13.7 nm.

CDI bar/aircraft orientation

If the CDI bar is to the left of the aircraft, the desired track (050M) is to the left, and vice versa. Turn toward the needle to intercept track.

Track made good (TMG)

When related to the current heading, this shows the degree of drift occurring. In this case eight degrees left drift. Track made good (TMG) is 030M/heading 038M. This is logical as the wind arrow shows a wind from the right, being about 070M at 20 knots.

Course selector arrow

The present VOR course selection is 050M, and the aircraft is slightly right of that course but closing on it, as witnessed by the “drift angle pointer” showing TMG of 030M. The calibration of the instrument in ILS mode is half a degree per dot. This calibration is automatically loaded when an ILS frequency is tuned. If a VOR frequency was tuned, the calibration would be automatically set at two degrees per dot. With this combination of wind from the right, aircraft close to the station, and an effective cut angle of 20 degrees, the aircraft would soon need to be turning right so as not to pass through the localiser course.

TO/FROM flag

The TO/FROM flag is NOT shown when an ILS is tuned.

CDI scale

This appears at 90 degrees to the course selector arrow on a HSI, not horizontally as is the case in the basic VOR/ILS instrument.

Glideslope

This is displayed on the right of the display. The aircraft is on the glideslope.

This mini-editorial is an abbreviated sample from the book “Flying Glass”, and from the soon to be released online ATPL “Aerodynamics and Aircraft Systems” course. Knowledge of EHSI modes form part of the Australian Civil Aviation Safety Authority (CASA) ICAO ATPL syllabus.

For more information go to www.aviationshop.com.au/avfacts/atp

and www.aviationshop.com.au/avfacts/Study_texts.htm 

and www.aviationshop.com.au/avfacts/avfacts/atp/default.htm 

This is one of a series on the B767 EFIS displays - check the editorial index for the others.

An interesting website within Boeing is that related to the quarterly AERO e-magazine.

One particular article to complement what you have read here can be found at:

http://www.boeing.com/commercial/aeromagazine/aero_09/flight_story.html 

This e-magazine number 9 includes details of the new B767-400 flight deck.

Best wishes

Rob Avery

ATPL Instructor