Hi
In an Airbus, there are several different positions:
pure IRS 1, 2 and 3.
pure GPS 1 and GPS 2 (if installed)
GPIRS 1 (computed by ADIRU 1: IRS1+GPS1)
GPIRS 2 (computed by ADIRU 2: IRS2+GPS2)
Each FMGC computes different positions:
radio (DME/DME, VOR/DME or DME/DME/LOC)
MIX IRS (which I think is not just a mere average, but it also takes into account each IRS "historical accuracy")
and then, among all those positions, each FMGC makes a mathematical blend depending on circumstances (and I don't know if it uses those kalman filters which I 've never understood) and then comes up with its respective FMGC position, which is the one used for its associated displays.
This FMGC position, when there is no radio nor GPS, is not pure IRS nor MIX IRS alone, but the MIX IRS corrected by the bias, which is the difference between the MIX IRS and the radio or GPS position.
When there is GPS or good radio position available, the FMGC position is the "scotch blended" one.
Kijagnim please don't hesitate to correct anything which is not correct.
By the way, very interesting that they did not use Kalman filters in FMS 1, if I did understand correctly.
Can you explain what Kalman filters are and do, in simple terms, of for "dummies" or is it impossible? I mean, what is the problem they solve? and How did the FMS 1 solved the same problem without them?
Thankyou very much