December 3, 201114 yr The ISA DEV entry on the PERF INIT page 1 shows 0 deg C and 32 deg F at start up (assumes an ISA day). These entries set deviation from ISA at cruise altitude, so for an ISA day both numbers should be zero. If the ISA deviation was +5 deg C the other figure would read +9 deg F, -10 deg C would equivalent to -18 deg F and so on.Kevin Hall
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