I still don’t get it. You can switch to “25.0 mode” for those areas.
You’re overthinking things, and you know too much.
The average radio operator just dials whatever the controller or the map tells him to. If the map says 118.200 he dials 118.200. If the map says 118.205 he dials 118.205. No need to remember or even know about the existence of 8.33 kHz or 25 kHz, or whether 118.200 overlaps with 118.205, or shares the center frequency, or not. All that knowledge is buried deep inside the radio unit. As long as the operator dials the right frequency, all will be well.
And “G-ABCD contact XXX on 118.205” is also a lot shorter than “G-ABCD contact XXX on 118.200 with 8.33 kHz separation”.
It’s working for maritime frequencies as well. Just dial channel 16 and the radio not only selects the right frequency or frequencies (note the possible plural), but also simplex or duplex mode, and the proper bandwidth. In fact, I even recall that certain maritime channels had different transmit powers than others. All being taken care of. No risk of operator mistake.
Did you know that by selecting 121.5 you are actually selecting a 100 kHz separated frequency? Probably not and in all fairness, it’s not something you should need to worry about. Especially not when you actually need 121.5 in a hurry.
You can switch to “25.0 mode” for those areas.
Exactly. All this .000 plus .005 mess is there just to (temporarily) allow 8.3 radios to use legacy 25.0 frequencies without having to explicitly switch between 25 and 8.3 modes at a higher config level on the device. Which then creates a new legacy we will be stuck with for decades.
Would have been neater to require users to switch between 25 and 8.3 modes, and use a different designator temporarily, eg. 130.000A for the old 25 and 130.000B for the new 8.3. Then drop the A/B suffix in 2018.
It’s a mess.
Would have been neater to require users to switch between 25 and 8.3 modes
That would require another switch on the radio, labelled something like “A” or “B”, or “narrow” or “wide”.
The proper solution would be to have pan-European frequency allocation. 8.33 is not actually required at all. I recall an AOPA study which proved it. It came about 100% purely because each country in Europe wants sovereignity over frequency allocation. The USA has far more aviation but doesn’t need 8.33. As usual we are paying a price for pointless politics. In this case it is a job protection scheme within each national CAA.
No, just a better shortcut than burying it deep in the menus like the 430/G1000 etc does now. A long press of one of the buttons would do. Instead we have a mess that we have to put up with forever.
Peter wrote:
In this case it is a job protection scheme within each national CAA.
You see job protection schemes in every questionable decision. 
I believe it is more a question of not wanting to give up decision power, or not being able to agree on how it is to be done.
ortac wrote:
No, just a better shortcut than burying it deep in the menus like the 430/G1000 etc does now.
The only thing that’s hidden deep inside the menus is the setting that controls your ability to select 8.33 channels in the first place. When that setting is disabled, you can only select 25 kHz frequencies, which means that going from, say, 118.200 to 118.300 requires four clicks of the little button. With that setting enabled, the three additional 8.33 frequencies in between the 25 kHz frequencies become available. Which means that going from 118.2 to 118.3 now requires sixteen clicks.
But it’s a one-time setting. Once its done you don’t need to worry about it anymore. The unit will select the proper center frequency and bandwidth for you, as long as the dial shows the number the controller or the map is telling you. The only real thing you’re going to notice is that you have to twist that little knob four times as much as previously.
A long press of one of the buttons would do. Instead we have a mess that we have to put up with forever.
It’s only messy if you design radios for a living. But the interface that is presented to the user has not changed a single bit. The big button is for the MHz (the numbers in front of the dot) and the little button is for the kHz (the numbers after the dot). There is no new terminology being introduced. Radios did not get an extra knob (or an extra function to an existing knob, like a long press) to select bandwidth, so we did not need terminology to tell the user which setting to set on that knob. It’s still as easy as before. Just dial the number that you’ve been told, and all will be well.
You can argue about whether the move to 8.33 kHz was necessary in the first place, and you can also argue about whether we should’ve gone to 12.5 kHz or 8.33 kHz or 5 kHz separation, and I’ll gladly join that discussion over a few beers. But once the decision had been made that we needed more frequencies, and once it was decided that we needed 8.33 kHz separation to achieve that, the solution that they came up with was actually fairly clever IMO, and completely workable for all radio operators (pilots mostly) within the existing way of working. No new skills to learn, no new knobs to understand, no new phraseology to roll out. And completely backwards compatible.
Airborne_Again wrote:
I believe it is more a question of not wanting to give up decision power, or not being able to agree on how it is to be done.
It’s the question who carries the cost. Pan-European frequency allocation would mean consensus between the countries in participation in overall cost of changing frequencies of stations, updating charts, plates, AIPs, navigation databases etc. New spacing means cost only to operators.
BackPacker wrote:
You’re overthinking things, and you know too much.
This is by far the best answer in this thread 
A lot of people here have solid to excelent background in electronics and we’re attracted to discussions like this one.
you can also argue about whether we should’ve gone to 12.5 kHz or 8.33 kHz or 5 kHz separation
It’s actually a very good point that 12.5kHz would not have needed the “fake” +5kHz frequency setting, because even old radios would have had enough selectivity to not pick up adjacent channels.
The 12.5 channels could have been shown as
130.000
130.013
130.025
etc.
LeSving wrote:
I still don’t get it. You can switch to “25.0 mode” for those areas.
Probably to reduce the probability of accidentally tuning the frequency in the wrong mode. Also, they would have to somehow designate whether any particular frequency is 25 or 8.33 spacing because there will remain some 25 kHz spaced frequency assignments even in the EU. Which could create a mess on the charts.
On a different note I’m quite sure I posted something here right after #8 but I don’t see it and the numbering isn’t interrupted which would indicate deletion/ moving of the post. I’m confused.
