View Full Version : Adirs

17th May 2004, 10:11
Does anybody know the difference between the conventional IRS/ADC installation and the ADIRS installed on the B777/Airbus?

18th May 2004, 10:57
On the 777, the ADIRU is one unit which handles all pitot-static info while providing all the usual stuff you would expect from an IRU. It has 6 layers of redundancy, "talks" with dedicated ARINC 629 buses...the bottom line is where there were several boxes, now there is only one!!

18th May 2004, 16:17
You're forgetting the Pitot and Static ADM's which take the air pressure and transmit it to the ADIRU's. That would make three "boxes" per system.

Flight Detent
19th May 2004, 03:56
Sounds just like the current crop of B737s!


19th May 2004, 16:25
IRS/ADC systems use a separate IRU and an ADC which is connected to lots of pipework so that pitot and static pressure can be sensed.

ADIRS's have a combined ADC/IRS and is fed pitot and static pressure from several Air Data Modules ADM's (1 pitot and 2 static ADM's per system). The main advantage is the removal of pitot and static pipework which can be prone to damage, blockage, water accumulation and it can be very labour intensive finding the location of these faults when they have occured.