by nzav8tor » Tue Jun 04, 2013 8:46 pm
Phew self taught instrument flying, good going so far!
Firstly, the 'ON' buttons referred to in an earlier post have nothing to do with the autopilot. This is the audio panel and is unrelated to the autopilot. Its function is to set what the pilot hears in the headset and which radio is being transmitted on. So Comm 1 and 2 refer to transmitting, BOTH is to listen to the frequency on both Comm 1 and Comm 2 radios.
NAV1 and 2 allow you to hear the morse code identifier from any tuned VOR station. This is a series of dot and dash tones that correspond to the VOR name or identifier, Rotorua is RO for instance, .-. --- So when in range you would hear dot dash dot, dash dash dash every few seconds. I can't remember the exact interval but it will repeat continuously while in range.
The DME button is the same, a full explanation is beyond the scope of this quick reply.
MKR is now obsolete but refers to so called marker beacons located on an ILS approach, there are none in NZ nowdays and only a few left elsewhere. (Mostly the USA).
ADF is the same as the NAV1/2 identifier but for the tuned NDB which you will have discovered from the chart for Taupo.
The main difference between the VOR and NDB is that you can choose which radial you want to fly to a VOR (or away from it) and you have the course indicator to line you up. The Automatic Direction Finder picks up the NDB signal (Non-Directional Beacon) and simply points at it. To fly a bearing inbound to an NDB you just orientate the aircraft so the needle is pointing to the bearing you want to fly. This takes a bit of mental visualisation!
I'm not entirely sure why your AP isn't flying to the VOR but heres some steps to make sure you've got everything squared away. (I know you've been doing most of them fine!)
0. Make sure your autopilot and HSI are synced to NAV and not GPS. There is a flip switch on the panel somewhere or you can make a keyboard shortcut in the controls, buttons menu.
1. Tune up your VOR, keep in mind the range of the station at low level won't be more than 50 or 60 nm (I could be way off actually, I don't think FSX is that accurate at terrain masking and so on but the point is that you won't pick up Palmy say when you take off from Auckland!)
2. Turn the OBS knob to centre the Course Direction Indicator (CDI) making sure the little white triangle is pointing toward the top of the Horizontal Situation Indicator (HSI).
3. Rotate the heading 'bug' to line up with the direction of flight. This is the orange bug and the other knob than the CDI knob to rotate it around the HSI bezel.
4. Start by engaging HDG mode on the autopilot to fly the heading you have selected. As stated earlier you can make adjustments to keep the needle centred.
5. Engage NAV on the autopilot and it should track the needle inbound to the station.
Points to bare in mind:
If you are not on a heading to intercept the course you have selected the NAV mode will not engage. So you have to be on an intercept course, the rules of thumb are 30 or 45 degrees off desired track. Basically put the heading bug on top of the fully deflected CDI needle, engage HDG mode and hit NAV. When the CDI comes 'alive' and starts to move the autopilot will drop HDG, change to NAV and turn to intercept the track, voila.
As you approach the station (VOR) the sensitivity of the CDI increases as now the distance between radials originating at the station are much less than at range. (Imagine the spokes on a wheel and the circumference reducing the closer to the hub). So as mentioned earlier, in NAV mode, the autopilot may roll side to side as it tries to keep centered as you get closer to the station. As you cross the station, you enter the so called, 'cone of confusion' where the reading is not reliable. In a few seconds the TO/FROM flag, that little white triangle, will flip to point behind you back toward the station. Once it stabilises you can happily re-engage NAV mode and fly 'outbound' on the same radial. For this reason it is a good idea to change to HDG mode, ensuring you HDG bug is aligned with your track of course, as you cross the station, maybe from 3 miles out until you cross and the needles stabilise heading away from the station.
Let me know if you still have problems using NAV on the autopilot, we'll get to the bottom of it. Oh, if its not already obvious, you can't use NAV mode for NDB tracking, it will only take its info from the NAV 1 radio (or the GPS)!
I'm sure I put some tutorials on here several years ago. I'll see if I can dig them up.