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0 votes
asked by (19 points)

My Coms frequency looks like it is stuck at 121.500 on the Cesna 172S (Steam-guage). When I try to change it, I am able to enter a new standby frequency using the Com/VOR Localizer rotary, but once I click the Flip-Flop key, the active frequency does not change and the standard frequency is reset to 121.500. Oddly, this does not seem to occur for Nav/VOR frequencies. Does anyone have an idea why this could be happening? I am following the manual instructions quite carefully and find this quite puzzling. 

1 Answer

+1 vote
answered by (2.2k points)

Hi MikeZ

I'm not with Laminar Research, just a fellow simmer in the UK and apologies if you know this already, but 121.500MHz is a frequency band reserved for emergency communications for civilian aircraft in distress.

To tune into the emergency channel very quickly, the COM1 flip-flop key is pressed and held, so that 121.500MHz is set up automatically in the GNS530 panel.

If you simply wish to switch between the COM1 standby and active frequencies, then the flip-flop key is pressed and released in quick succession.

Bottom line: short press of flip-flop key to change frequencies, long press to select the emergency channel.

The same thing applies for COM2 in the GNS430 unit below

Hope this helps?



commented by (19 points)
Thanks Greengolfer!

I did not know this, but it is relevant and good to know. I did not see this in the Xplane manual , but I can see it in the real Garmin GNS 530 manual. I guess a good explanation could be that the interface is interpreting my clicks as long clicks. In the manual the definition of a long click is two seconds and a long click will set the active frequency to 121.500. It would be useful if someone could confirm that a long click does this on their version.

On puzzling thing is that clicks occasionally lead to the standby frequency going to 121.500 and leaving the active frequency unchanged. This appears to not be something that should be happening in a real unit. Can anyone confirm that?

Thanks again,

Mike Z
commented by (2.2k points)
Hi Mike

I use the left mouse button when clicking on the flip-flop switch, very quick click to change frequencies, press and hold to select the emergency channel 121.500.

If I press and hold the flip-flop switch for a second time, then the active frequency stays on 121.500 and the standby frequency also changes to 121.500.

Not being a 'real world' flyer, I can't really say if this is correct or not when compared to a real aircraft?

commented by (19 points)
Hi Greengolfer,

Yes, I can see that. Thanks again for explaining this. I am not completely sure what is going on but I suspect that some of my clicks have been interpreted as long clicks. So this now makes so much sense. It would be great if this was in the manual.