A320 INTEGRATED STANDBY INSTRUMENT SYSTEM

A320 ISIS

The Integrated Standby Instrument System (ISIS) integrates the 3 classical standby instruments (Airspeed, Altimeter, Horizon) into one single instrument. The ISIS system displays the following information:

  • Attitude
  • Airspeed and mach
  • Altitude
  • Barometric pressure
  • LS function
  • Bugs

+/- activation pb

  • Two pushbuttons labelled “+” and “–” are used to adjust the level of brightness.
  • The brightness of the screen automatically adjusts after power-up tests. This is because of the photosensitive cell located on the surface of the ISIS system display.
  • The “+” and “–” pushbuttons then allow this initial brightness to be manually adjusted and changed.
  • Note: The system must be reset after 350 h of continuous electrical supply using the ATT RST pushbutton.

ATT RST

The attitude indication can be reset by pressing this pushbutton for at least 2 s. The aircraft must be level during this procedure. During the reset time (approximately 10 s), the “ATT 10 s” message is displayed on the screen. This pushbutton is also used to realign the system, if excessive aircraft movement is detected during the alignment phase.

LS pb

Pressing the LS pb will display the LS scales. Pressing the LS pb again will remove the LS scales.

BUGS function selection pb

Pressing the BUGS pushbutton will activate the BUGS function and display the bug values to be selected.

SPD BUG and ALT BUG columns

  • The SPD BUG column gives four speed values (in knots) that can be selected by the crew.
  • The ALT BUG column gives two altitude values (feet) to be selected by the crew.

BUGS value selection knob

  • It allows the bug value to be set by rotating the BARO knob. This value cannot be lower than 30 kt for a speed bug, or a negative value for an altitude bug. 
  • Pressing the BARO setting knob, once a bug value box is activated, will deselect the bug value. 
  • The “OFF” label comes on close to the activated box.
  • The entered values are memorized by the system, when exiting the screen, by pressing the BUGS pushbutton, or after 15 s without any pilot action.

+/- box activation buttons

Access from one box to another is obtained by pressing the “+” or “–” pushbutton. When a bug value is entered, access to the next box is obtained by pressing the “–” pushbutton. The box becomes active and flashes. The “+” pushbutton can be used to return to a previous box.

⮜ Cockpit Panels
A320 Guide ⮞