Questions regarding autopilot and NAV radios (VOR/ILS/DME)

[sebihepp 1]

Hello,

 

I have some questions about using the navigation radios. To fly a specific radial or an ils, I just enter the frequency and course in both, NAV1 and NAV2, and press the VOR/LOC or APP button. That's working perfect.

 

But let's say I want to fly radial <xxx> of VOR/DME <zzz> and after <ddd> DME <zzz> turn into ILS <iii>. Therefore I want to tune VOR <zzz> first and ILS <iii> as standby. After <ddd> DME <zzz> I switch Frequency and intercept the ILS. But... I need to adjust the course first. And that's twice. I can't switch radios, because the course would be wrong and I can't switch course, because the plane would turn immediately, because of the changed course. For now I set the current heading, press HDG SEL and then tune the ILS <iii> and thereafter press APP again and hope, I was fast enough to not overshoot the ILS.

 

This way seems... uncomfortable. I would like to tune NAV1 to VOR <zzz> and NAV2 for ILS <iii> and then use a switch to switch between them. Or to switch between two VORs.

 

What do you do in such a situation?

 

best regards

sebihepp

[jkowalski801 0]

Generally swapping NAV freqs with VOR/LOC active seems like a no-no to me and I would think that using HDG SEL in between is a better idea. However if you feel like pulling off such stunts the you actually can and that's because to intercept a LLZ you DON'T dial the course as it serves NO purpose! So technically you should be able to just switch the freqs and that's it. Although I never tried it personally.

[Spin737 102]

to intercept a LLZ you DON'T dial the course as it serves NO purpose!

On some planes that's true. Not on the 737.

 

sebihepp, do you have a chart we could refer to? There's usually a "Lead Radial" which is where you could retune the radios or some area where you should have enough time to set up the instruments. Also, you could simply follow the VOR course in first in VORLOC and once you get a good heading established, you could simply track via HDG SEL and have the LOC armed.

 

Or you could simply use LNAV.

[jkowalski801 0]

On some planes that's true. Not on the 737.

 

Thanks for correcting this.

 

sebihepp, I think you may find the following quote from the FCOM of some interest:

 

 

Note: If change to a localizer frequency is desired when captured in

the VOR mode, disengage VOR LOC mode prior to selection of

the localizer. VOR LOC mode can then be reengaged.

[sebihepp 1]

okay, thanks. It is about the published ILS 07 of Stuttgart (EDDS) 23 SEP 2010 (should be actual). You fly R230 of LBU and after 15 DME LBU you turn left into ILS. I won't upload the chart, because of the copyright. But you should be able to get it via VATSIM, IVAO or www.ead.eurocontrol.int

 

When I disarm VOR/LOC, what does the autopilot do then? I mean in this case it hase no other mode active. Does it default to HDG SEL? Perhaps it is better to use HDG SEL in this case to make sure the autopilot doesn't do anything unexpected.

 

What do you mean by using LNAV? Is there a way to programm radials and distances into the FMC? - I just read the second tutorial. The Questions is answered there at page 96 and following.

[Spin737 102]

You need to work with the FMC on this one. Do some of the tutorials.

 

Normally, you would go to the DEP/ARR page and select the ILS7 approach and then you'd also select the LBU transition. By selecting the LBU transition, and linking it up to your route, the LNAV will then be able to follow the course you describe. When you come around the turn, you'd select APP on the MCP when the LOC and G/S pointers are in view. The APP mode will take over from the LNAV when it captures.

 

Easy! :)

[Tabs 2,790]

The real 737 absolutely does require the course input for a localizer - there's a shortcut for doing it built into the NGX due to the fact that the FSX scenery BGLs and the real life navdata have different courses due to magnetic variation changes over time. The NGX reads the scenery BGL and tunes the actual course that's in the sim world.

 

The option is "SET FSX LOC CRS" on the SIMULATION page. The real life airplane does not have this option.