I'm reading the very pleasant Mr. Maltby's "Flying the One-Eleven". Some time I do it, I like it a lot.
At chapter 6 he recommend a mental picture of the approach path and that's ok. http://www.dmflightsim.co.uk/flying_the_1-11_6.htm
My question is: when I have to start the turn for the base leg from the parallel track? Are there some rules?
Thanks a lot!
It is , in fact, very unusual to fly a circuit in preparation for an ILS approach, but if you are doing it as per DM's method, then you need to wait until you are at an angle of about 30 degrees to the NDB with the NDB behind you. In the example you have shown you would start your turn onto base at a QDM ( shown on the RMI ) of about 039. Your initial heading would be about 339 for a 90 degree base leg ( although in the real world you would probably aim for initial inbound at 45 degrees, requiring a heading of 024 ) . Remember that in strong winds you will need to correct for drift. Even in still air you would start your turn onto final rather before that shown in the example of waiting until you had a QDM of 069, because that would inevitably result in your overshooting the localiser of the ILS