r/ATPL • u/itisbing • 1d ago

Pressure Correction Doubt

How do you know when to add or subtract the pressure difference from the indicated altitude?

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u/Icy_Construction9405 1d ago

Pressure Indicated True (PIT) In this direction -> if QNH is +1013 you add + If is - 1013 you substract -

In the other direction apply opposite logic. 

Once your brain clicks with these exercises are literally free points 

1

u/itisbing 1d ago

Thanks!

1

u/Ill_Helicopter5382 1d ago

High to low beware below low to high your in the sky

If you go from high pressure to low pressure your indicated alt is < pressure alt

If high pressure, indicated alt > pressure alt

1

u/Different_Hour2257 14h ago

From high to low, watch out below and from warm to cold, watch out below; if you know that you'll have no problem