lord_raunak
5th Oct 2012, 12:22
an aircraft at 19,000ft wishes to communicate with a adf at 1,400ftamsl. what us the maximum range at which it is likely to contact?
a. 175nm
b. 216nm
I got the answer as 219, so it has to be option b.
But the book says its a.
A little confirmation really does boost the confidence.
Do reply.
sgenie
6th Oct 2012, 01:15
Max distance would be 1.25*(sqrt(TX)+sqrt(RCV)), where TX is the transmitter height, RCV is the receiver height
Actually, the formula is 1.23 x sq rt H + 1.23 x sq rt h, where H is the height of the aircraft and h the height of the antenna off the gorund. They must be calculated separately - if you add them together first the square root is wrong.
In your case the answer is 215.56 so you are correct, but you may have used 1.25 instead of 1.23. In any case it is the nearest answer.
In fact, the question is wrong in other ways - that formula is for VHF, which an ADF isn't, and it should be an NDB. The ADF is in the aircraft. Also, you don't "communicate" with an NDB! :) It's a passive instrument.