Hi all,
I got stuck on one of the questions regarding altimeter setting. I solved the question already and I just want to confirm that I did it correctly. Here is the question: prior to descend you incorrectly set the altimeter subscale to 1002 hpa when the actual QNH is 1020 hpa. If destination is 860 ft. The reading of the altimeter on the ground at the destination will be?
Here is how I did it. 1020-1002 = 18 and 18*30 = 540 and 860-540 = 320.
I followed tis rule. When low to high, the altimeter will underread
Also, if i don't know the QNH at the departure aerodrome, can I set the altimeter to read the airfield elevation?
Would the altimeter read zero if I set the QFE
Thank you
There are a few old memory aids for altimeter - some going back to the second world war. "HIGH TO LOW LOOK OUT BELOW" was a reminder that if you are flying towards a low pressure area with a constant sub-scale setting, you altimeter will tell you that you are higher than you actually are.
Also "WIND ON PRESSURE WIND ON HEIGHT" is a reminder that if you set a higher subscale reading, your altimeter mainscale reading will increase and v.v.
Your calculation is correct. With 1002 set your altimeter would underread by 540 feet.
