Just read a question on the use of the ILS and its limits. Page 297. The question: When, on the ILS can you descend on the GP?
1st part: When cleared for the ILS procedure. ..... Correct.
2nd part: When you have captured the localiser within +/- 5 degrees C...... absolutely incorrect.
Now the second part is obviously a huge mistake but, if the author meant +/- 5 degrees of the centreline (omitting the reference to temperature), which I think he did, isnt he still incorrect.
Please correct me if I am wrong here but I was taught that the approach should be thrown away when you are descending on GP and you go outside either half scale fly up or down or 1/2 scale fly left or right. And ......
On page 145, he says one dot on the ILS indicator = 1/2 degree (which I think is correct) so therefore on a normal HSI when flying the ILS, his answer should be +/- 1.25 degrees (or within half scale). This is a big contradiction to his answer (forgetting the reference to temperature).
I know what I used to know, but the numbers now have me confused big time!
To clarify this..........
Should the answers for the limitis of lateral navigation, when asked when one can descend with the procedure be:
+/- 2.5 degrees for a VOR approach. (full scale deflection = 5 degrees)
+/- 1.25 degrees for an ILS approach (full scale deflection = 2.5 degrees)
This book just gets more and more confusing!
barit1: It has been discussed in depth on Prune as well and the problems still crop up!!!