Pressure Altitude on TO Graph
I've got myself a little confused having read someones comment on here.
On a Take-off performance graph for a SEP.
Say...
Airfield Elevation: 100ft amsl
QNH: 1025
So pressure altitude would be -260ft
Now on the graphs in question there is no graduations below SL (sea level) but I would still count down from SL and draw a line at roughly -260ft against the temp. shouldn't I?
Hope this makes sense!