Dim Wannabee needs ISA help
I understand that temp an be stated as ISA (or indeed JSA) plus or minus a figure
eg: Temperature is ISA + 7.
What I'm really stuck with is the nature of the calculation. Does it require one to apply the correct mathematical technique as in:
ISA = - 57 so ISA + 7 would be - 50 and ISA = -57 and so ISA -7 would be -57 - (-7) = -57 + 7 = -50
Both can't be right.
Many thanks for any help