Where is magenta line in VOR?

[Danesh_D]

Hi all,

I am newbie so sorry if my questions are silly. I tried to land with Boeing 737. I set the destination in "Select Approach" GPS and it showed the way to destination with a purple line. The problem is when I intend to land in destination airport, however I have specified the destination and the aircraft is on autopilot and both "Heading" and "Approach" are on, but the magenta rectangle in VOR which shows if you are exactly on the runway or not will never appear. Alsoin VOR DME doesn't show the distance between aircraft and airport. How can I activate it to a perfect landing? BTW, is it called ILS landing?

Regards,

D.

[a1]

there is a really good tutorial.

http://www.simviation.com/cgi-bin/yabb2 ... 1111322151

it should answer everything.

[Danesh_D]

I know. I exactly followed that but it didn't work for me like that. Its weird!

D.

[TSC.]

Sounds like you haven't got the Nav1 radio tuned to the correct frequency, or you have tuned it, but not flicked it over to the active.

Have you looked up the correct frequency & runway heading on the map?



TSC.

[Danesh_D]

Yeah. Thanks for the tip. I set to frequency of destination airport and magenta line showed up and by holding "APP" button in autopilot it pur the aircraft along the runway. Now, the problems are:

1. DME still doesn't show the correct distance between aircraft and the runaway.
2. When the aircraft is pretty close to runaway, the magenta line suddenly disappears and "APP" button turns off. It seems the autopilot leaves the control of the aircraft suddenly. However, the aircraft is not completely in the correct way and it need small changes.
3. In landing tutorial "APP" button is always on and magenta line never disappears.

Am I doing something wrong?

D.

[ashaman]

1. DME still doesn't show the correct distance between aircraft and the runaway.

How great is the error? If the error is small, remember that a DME equipment measures the distance between your plane and the VOR itself, like the hypotenuse of a scalene triangle, not the distance on ground.

This generates an inevitable distance error that is bigger the closer you get to the VOR.

2. When the aircraft is pretty close to runaway, the magenta line suddenly disappears and "APP" button turns off. It seems the autopilot leaves the control of the aircraft suddenly. However, the aircraft is not completely in the correct way and it need small changes.

The signal of a VOR disappears right over the VOR itself, as it is an array of directional radio beams. If the signal disappears, maybe is because you are so near the VOR that you find yourself in a "dead zone", so to speak.

3. In landing tutorial "APP" button is always on and magenta line never disappears.

This ties itself to the last part of the previous question. You're following a VOR radial, not an ILS, and it's only normal that the plane it's not perfectly centered with the runway nor the signal behaves like the signal of an ILS. the landing tutorial uses an ILS, that's why you find some differences.

ILS is ILS, Vor is different.

[Danesh_D]

Well, I followed exactly the tutorial step by step. I thought I am following ISL and not VOR! Well, I am a little bit confused. How can I follow ILS for landing? Also, what are differences and why you say that I am landing based on VOR? I should also say that DME doesn't show any value at all. It is always "---"!

D.

[Brett_Henderson]

Many ILS do not have DME. Some do, but it's not needed, as you've got a glidescope to guide you down. The only reference for distance to the runway you need on final, is to not get too low, too far out.

Besides that though.. I can see a few confusions here. Normaly, this is where I suggest that you practice this stuff in the 172 using a good old fashioned VOR/ILS gauge.. not the HSI (especially not the glass HSI) that you find in the more advanced planes... and not in conjunction with a GPS. That's where I think the confusion lies. If you're using the CDI (magenta box) to get lined up with the runway via GPS, the nav/gps switch is no doubt in the "gps" position. This renders it useless for the ILS until you switch the nav/gps button back to "nav". I suspect that's why the CDI "suddenly disappears ". GPS approaches are fine too (the ones you can select in the GPS and that show up as a white course line), but they are not precision approaches. In fact, they aren't much better than a VOR or NDB approach.

Instrument approaches are very VERY realistic in the sim which makes just jumping into a 737 and doing a GPS/ILS approach not something I'd advise. You miss out so much on the learning and fun working up to that type of approach. Crawl, walk and then run  :)

[ashaman]

...why you say that I am landing based on VOR?...

Sorry, but what's this thread's name? You can't go around asking about a VOR procedure and then mean ILS on the sly, you know.


Or perhaps did I read wrong? :-/


As for the DME, as Brett already wrote, it's not a mandatory equipment, neither for the ILS's nor the VOR's (though VOR with no DME are rare, are not unheard of, and so are the ILS's). If you're not receiving a distance at all, then the ILS or the VOR you're tracking is devoid of DME. Simple as that.

[Nav]

Well, I followed exactly the tutorial step by step.

Speaking as the author of the tute, Danesh, with respect, I suspect that you maybe rushed though the very first bit! It says:-

[i]"This shot shows a default 737 at 2,500 feet and 220 knots, 21 miles out of Miami Intl., inbound to Runway 9L.