terry <tfmann@iprimus.com.au> wrote in news:234756e2-a583-4cbc-8f42-
9fc499a48ca3@c65g2000hsa..com:
> I am confused by this practice commercial nav question. ( at least I
> am confused by the answer in the book which was b. but I think both a
> and c are correct), but I appreciate some other opinions.
>
> Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on
> subscale
> ( thats equivalent to 29.92 inches of Hg for the US folks)
> Day 2 Altimeter reads elevation of 1000 feet
> Assuming the altimeter subscale was not changed between day 1 and day
> 2 it could be said that
>
> a. The QNH is higher on day 2
> b. The QNH is lower on day 2
> c. The pressure altitude at the airport is lower on day 2
> d. The atmospheric pressure at the aerodrome has not changed.
It's A. It could also be C if the airfield has a serious subsidance
problem.
Bertie