help on commercial test

[wessidmike]

if you have the book it's gleims page 224 question 42

"while cruising at 135 knots and on a constant heading, the ADF needle decreases from a relative bearing of 315 degrees to 270 degress in 7 min. the approximate time and distance to the station being used is"

a 7 min and 16 miles

b 14 min and 28 miles

c 19 min and 38 miles


They say answer A is correct "when a relative bearing doubles in a specific time , the time to the station is that time (the time to double the relative bearing) . Thus the time to the station is 7 min since the TAS is 135 kt., the distance to the station is 15.7 NM (7/60*135)


Where in this question do they say anything about doubling the Relative bearing... I had my instructor look at it and they didn't know either. Can anyone explain this any better than the book. In other problems they stated that the relative bearing was doubled, but how do i know when it's double and when it's not, if it's not stated?

 

[Big Duke Six]

The key here is the word "relative". In the example, the needle starts out at 315 degrees, or 45 degrees off your beak assuming you have 360 degrees at the top of the ADF. It then moves to 270, or 90 degrees off, in 7 minutes. The relative bearing doubled from 45 degrees to 90 degrees. As another example, it could have moved from 350 degrees to 340 degrees, thus doubling from a relative bearing of 10 degrees to a relative bearing of 20 degrees.Hope that helped!

 

[wessidmike]

Yeah thanks for the help, i think like all the FAA quesitons, they could have worded the question a little better. my problem is, I didn't asume the MH was 360!