Originally Posted by
mcdhu
Apologies for the thread drift, but can anyone enlighten us on the effect low temperature has on the A320 FPV. Most folks believe that it is purely IRS derived, but it has a barometric input too which must be affected by temperature.
I tried following the ILS GP in ISA -20 using the FPV and it appeared that around -3.7 was selected to maintain the GP but the actual FPV appeared to be indicating less than that. The sim was a CAE device recently upgraded to 1.9.
Any ideas?
Cheers all
mcdhu
Yes. The FPA is computed by inertial (GS) and barometric data (baro rate of descent) and it is ISA referenced.
What you noticed is correct.
In cold temperatures the ADIRS sense higher altitudes and thus steeper calculated paths have to be flown by the pilot to compensate this effect.