Tolerance of Standby Altimeters in Jet aircraft. (Airbus)
HiGuys,
Recently, had a mate who shared his experience with me from his flight. His Primary altimeters had a discrepancy of 80ft and his standby altimeter on the ISIS (Integrated Standby Instrument System)’s PFD had a discrepancy of 300ft with his altimeter.
From my understanding, in RVSM airspace, only the discrepancy between the 2 primary altimeters is taken into consideration, with a tolerance of 200ft. Nothing mentioned about the standby altimeter as it’s not rated for RVSM.
My questions are:-
1) Any of you guys are aware if there is any tolerance for standby altimeters?
2) How are the AAD/TVE/ASE determined by the ATC?
AAD is the difference between the transponder Mode C altitude and the assigned altitude / flight level. ASE is the difference between the pressure altitude displayed to the TVE is the vertical geometric difference between the actual pressure altitude.
3) What is YOUR tolerance for a discrepancy in standby altimeters reading?
Thanks for your time and comments.