PPRuNe Forums - View Single Post - IRS alignment on Airbus
View Single Post
Old 24th July 2006 | 17:35
  #13 (permalink)  
Max Angle
25 Anniversary
 
Joined: May 2001
Posts: 1,424
Likes: 34
From: London,England
If you have GPS primary it really doesn't need to be a full align as it updates itself on application of take-off thrust.
One aspect which is often overlooked is the effect that IRS drift can have on track information (green diamond and flight path vector) and the wind vector computation (and hence VAPP computation for G/S mini). I guess it depends on the direction and amount of drift but an IRS that is 5-6 miles out can have a huge effect on these computations. It's the reason that the track diamond doesn't seem to work as well in the a/c as the simulator. It is also the reason why the two wind vector displays are always a little bit different, if you have a lot of drift they can vary by a huge amount and cause the VAPP computed by each FMGS to be way out of sync with other. Like all computers it's garbage in, garbage out.
Max Angle is offline