Hi all!
I'm return to home, and i'm ready to answer for you questions.
Well, let's see to VOR navigation in TU-154 clearly.
Suppose, we fly in range of VOR beacon, and our 1-st nav receiver has tuned for desired channel (select freq by panel 445, right part). We have a good signal, and we can see green lamp on panel 445 - OT (FROM) or HA (TO).
We should select desired radial by choose digit on panel 445 (left part). If our autopilot in STAB mode, we can press button A3-I (349) and our plane will fly on radial under VOR control.
But it's will only if our plane already stay on selected radial. If not, we need some things before.
Suppose, our plane is far from desired radial. How we can reach selected path? Here, we should use our compass system.
Let's see to PNP (HSI) instrument (102). Here, we can see white needle (F) and heading digital wheels (C). We can set desired heading by handle (D) rotation.
What heading we should set? Indeed, our desired radial!
AP/VOR subsystem will turn our plane to heading +- 30 deg from HSI heading (102-C, 102-F). Plane will fly this heading until they reach selected radial ( selected from 445 panel). After reaching, plane will turn to radial, and continue flight under VOR control. Needle (102-G) will show deviation from selected radial.
It's will work, if our departure airport is near from VOR beacon. Contrary, if we has fly 1000 km before entering to VOR zone, we get difference between magnetic heading (which VOR use) and gyro heading (which nav system of TU-154 use as default). Now, for correct navigation, we should take in mind "fork" (read about it in documentation!) or switch our HSI (PNP, 102) to magnetic heading by turn sw. 416 to down position.
So, what is the method for flying FROM the VOR source?
It's simple. Suppose, we want fly on radial 90 (magnetic heading 90). We set 090 to (445-left), and 90 to PNP (HSI, 102 D-C-F). Our plane is situated in East from VOR.
In this case, our plane will go to radial, and fly under VOR control - FROM beacon.
If we want fly TO beacon, you should set 090 to (445-left), and 270 - to PNP (HSI, 102 D-F-C). In this case, you will fly TO beacon. After reach beacon, nav receiver will switch green lamp TO -> FROM, but plane should continue flight under VOR control until plane has left nav signal.