VOR DME approach question

[bobsk8 21]

Today I flew an approach to Rwy 7 at MKJS which is a VOR DME approach. I almost always fly ILS approaches, so when I was flying this approach where there is no ILS I noticed that I got a glide slope indication on the display. My first question is, since there is no ILS, where does this vertical guidance come from , is it calculated by the FMC from the DME information and the altitude at the runway? The other question is, I armed the approach, but it didn't lock to the glide slope indication, so does that not lock vertically in this type  of approach?  

[Francescom 4]

Today I flew an approach to Rwy 7 at MKJS which is a VOR DME approach. I almost always fly ILS approaches, so when I was flying this approach where there is no ILS I noticed that I got a glide slope indication on the display. My first question is, since there is no ILS, where does this vertical guidance come from , is it calculated by the FMC from the DME information and the altitude at the runway? The other question is, I armed the approach, but it didn't lock to the glide slope indication, so does that not lock vertically in this type  of approach?  

The "Glide Slope" indication that you have on the PFD is the "Vertical Deviation" and It has a different shape, rectangle instead of diamond, both Magenta.

 

Vertical Deviation comes from the VOR Procedure in the Navigation Database. When you Select the VOR APP the system loads also the Vertical Profile.

For VOR procedures anyway, I Suggest to follow the Charts for the right Descent Profile since, also in the Real Bus, the Vertical profile is not fully correct (some Company are allowed to follow horitontal profile but not vertical). 

Generally when I do a VOR APP I select the procedure on the MCDU but I use VOR MODE on the EFIS Control Panel and on the ND and I follow the procedure manually with Chart.

For this kind of Procedure after a check of the Wind and GS during APP, TRACK, FPA mode is very useful to perform the APP.

If you Select APP Mode during VOR APP the A/P will follow the horizontal and vertical profile of the Nav.Database Procedure until MDA then it will disconnect automatically and the system reverts to basic mode HDG/Vertical Speed. Dirrerence from ILS can also be seen on the FMA, during a VOR APP the FMA Displays NAV instead of LOC in the third column and "FINAL APP during final APP .

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[bobsk8 21]

Well thanks, now I understand. 

[fabioleroy 0]

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Hi Francescom,

I'm sorry for my off topic question. It seems you have a different font from the mine in the PFD, you take these shots from the game, right? If so, how did you get this? The readability of this font is better from the one I'm using

Thanks so much,

F;

[The Dude 6537]

Those are not screenshots from the "game". They are from another program.

[Francescom 4]

Yes Frank, this Screen coming from other source

[PMSoares 74]

Bobsk8, you should be able to follow the vertical path accordingly. Bear in mind that you must be in a compatible altitude in order to have the auto-flight system doing it. If you're too high on the profile, you may not be able to capture the vertical path. A good rule of thumb is to multiply your altitude difference (in thousands of feet) by three in order to know how far you should be from the waypoint/station. For example. You´re at 15.000 ft and you should be at 3000 ft at a given waypoint. How far from this waypoint should you be? 

 

15.000-3000=12000

12000/1000=12

12 X 3 = 36

 

You should be at 36 Nm from the waypoint if you're right on a good vertical profille.. If you're closer taht 36 Nm, you're high. If you're farther than 36 Nm, you're low. Allow 5 Nm for deceleration and configuration if the waypoint is a IAF or FAF. 

 

The reverse calculation also is useful. For example. I'm at 42 Nm from a waypoint which should be crossed at 8000 ft. What should be my current altitude? 

42/3=14 X 1000 = 14.000 ft   So we should be 14.000 ft higher than the crossing altitude of the waypoint. 14.000+8000=22000.  So, at 42Nm from a waypoint that must be crossed at 8000 ft, we should be at 22.000 ft. 

 

Have a nice flight!