CYUL LOC 24L: DME Information

[MRFarhadi]

Hi,


I was doing a practice Localizer approach into Montréal's runway 24L the other day and as it is with LOC approaches, a DME is required for Continuous Descent Final Approach procedure. What YUL and some other airports have done, is to pair both localizer ends of a single runway into a single localizer and DME antenna; only leaving Glide Slope equipment to be separated for each approach.

What Navigraph and Aerosoft navigation data provider have done, is to pair their respective localizer only with the DME that its ident is the same. So, when using a similar frequency for both localizers, one end Will receive DME information and the other Will Not. e.g.:

- Approaching YUL 24L: LOC = IQM (110.50), DME = IOA (110.50) => No DME Information
- Approaching YUL 06R: LOC = IOA (110.50), DME = IOA (110.50) => DME is Available

What I reckon happens in real-life is that the DME is just paired with the same frequency and rest is easy: any localizer end you use for the approach, you'll still have the DME paired with it. Only the airport operator (ATC in this case) needs to remember to change the ident when active runway has changed to the other side.

As it's not possible to dial-in "110.50" into B744's CDU Radio Nav page, what alternative can I use to shoot LOC 24L into YUL?




Cheers,

[Hardy Heinlin]

Hi,

you could enter IOA on the FIX INFO page and read the direct distance in the first line under BRG/DIS.
Edit: But this DIS will refer to the LOC station position, not to the G/S station.

Or enter 110.50/057 on the NAV RAD page in 4L and consider it a backcourse approach :-)
When you enter /057 instead of /237, PSX will cause the simulated ATC to activate IOA instead of IMQ.


Regards,

|-|ardy

[MRFarhadi]

Thanks Hardy.
I already tried using FIX INFO page, but the problem is that the accuracy isn't enough as you'd need the decimal places for short distances too, as half a mile of difference would cause up to 200' of vertical error.
Trying to use the back-course would even be more of a negative training too; but honestly there'd be no other alternatives anyways. It's a problem on the navigation service provider and I'll probably be messaging them soon.

Once again, thanks for the ideas and thoughts on the matter.


p.s. Is ILS' DME channel displayed on the PFD only "coupled" with the navigation database? or it simulates listening on the paired frequency as well?
Cause if it does actually simulate utilizing the DME channel, I reckon the issue would solve itself.

[Hardy Heinlin]

The PFD shows the frequency value that is tuned in the receiver, and when the morse ID from the radio signal is decoded (after circa 10 seconds), the PFD shows that morse ID from the radio signal, not from the FMC nav database. This works even when the FMS fails.

Yes, if the other ILS also had a paired DME in the ARINC database, there would be two DMEs at the same location but with different IDs, and PSX would receive either of them.

I don't think that Lido or Jeppesen will change their system, though.

You could add that DME with Navburo, I guess.

[MRFarhadi]

So, now that only "IOA" has a paired DME (Channel 42 - Paired to 110.50 MHz), while "IMQ" doesn't have any, shouldn't a DME distance be displayed under the conditions you mentioned?

[Hardy Heinlin]

We're talking about the global database in PSX.
The global database provides data to:
• the simulated FMC nav database
• the simulated radio stations on the simulated planet
• the simulated receiver electronics
and dozens of other simulated things in PSX. The FMC model is just one of many parts in the PSX universe.

The global database in PSX comes from the ARINC master files of the respectice providers Lido or Jeppesen.

The IMQ DME is missing in the ARINC master files. Therefore it will be absent in all simulated parts: Simulated planet, simulated FMS, simulated receiver electronics, simulated ATC, Instructor maps etc. So the IMQ DME will appear nowhere in PSX.

[MRFarhadi]

Got it.

Thanks for clarification. Gonna practice another approach then : )

Appreciate your response.