8.33 Radios for GA.... When? Why?

[phiggsbroadband]

Does anyone know when and why 8.33khz Radios are required for GA aircraft ?


I understood that frequencies were being issued for stations in contact with Commercial Air Traffic (say above FL240.), but don't know how or why this affects GA aircraft.


Does it also mean that aircraft not fitted with a radio at present, will need to have them fitted?

[dont overfil]

Does anyone know when and why 8.33khz Radios are required for GA aircraft ?


I understood that frequencies were being issued for stations in contact with Commercial Air Traffic (say above FL240.), but don't know how or why this affects GA aircraft.


Does it also mean that aircraft not fitted with a radio at present, will need to have them fitted?
Last I heard was the end of December next year. However, most of the planned dates for various changes have been put back so don't panic yet.
I have not heard of any plans to make radios compulsory in class G but increasing amounts of class E radio is required.

[Johnm]

The reason for 8.33 radios is because Europe can't get its act together on allocating frequencies on European rather than a national level, so they can't reuse frequencies on the basis of ensuring that two users of the same frequency are far enough a part for it not to be a problem.

[Silvaire1]

The US does not and will not need more than 760 channels because physics doesn't require it anywhere in the densest US airspace. It's obvious to me that no more than 760 aviation band allocations are located within any circle of VHF radio reception in Europe, and that 2280 available aviation band channels are not necessary within any such circle.

It's also obvious that the 8.33 MHz name was created, as opposed to the normal tradition whch would label them as 2280 channel radios, to discourage people from thinking about the geographic reality.

When the axe does eventually fall there's a market for the used 760 channel radios in the US, Barnstormers and Trade-a-Plane are places where they could be advertised. Prepayment and selling to individuals might help avoid opportunistic games. Apparently radios checked and shipped to US dealers have been known to 'fail' during transatlantic shipment.

[TheOddOne]

I understand that a UK work-round is that you will be considered compliant after 31 Dec 17 if you carry a 8.33 portable in the aircraft, so you can still use your panel 760 set to communicate with all the stations still on 25khz spacing. We've just bought a 8.33 portable for Club use.

One question that I asked an equipment supplier but they were unable to answer... What happens to the 25khz spacing radios we all use for Air/Ground (mostly ICOM AC110). They didn't know. Presumably, provided there isn't a nearby 8.33 with an adjacent channel, you can still keep transmitting on the old 25khz channel without interfering with anyone. ICOM do now market a new 8.33 radio for ground installations but why spend money if you don't have to?

TOO

[Jan Olieslagers]

The urgency depends on where you are, or, more precisely, where you fly. Eindhoven EHEH already has an 8,33 frequency for its tower.

[n5296s]

@Silvaire +1

It just doesn't make sense to me. Presumably someone must be making either money or career advancement out of this.

[wigglyamp]

It would make no sense for Europe to introduce this for commercial gain when the vast majority of the new equipment required to meet the mandate is supplied by the U.S.

[trevs99uk]

In the UK the number of Frequencies allocated must have gone down in recent years with most of the smaller Airfields reverting to the Safety Com frequency due to OFCOM,s excessive fee,s.

[trevs99uk]

The CAA have applied to EASA for some exceptions to the 8.33 requirement..

[Whopity]

The problem of channel assignment is constrained by physics rather than politics. Interesting how no other organisation involved in Telecommunications has adopted a spacing of 8.33 KHz!

[Heston]

Read this

http://www.lightaircraftassociation.co.uk/2013/Magazine/May/radio.pdf

[chevvron]

Interesting how no other organisation involved in Telecommunications has adopted a spacing of 8.33 KHz!
My original (1986) Icom IC A2 was configured for 12.5 khz channel spacing which would have provided plenty of extra channels over 25 khz; why they went for 8.33 instead we'll never know.

[chevvron]

'cos they ran out of 12.5 kHz spaced channels. You tried getting a frequency assignment recently?
Personally no, but as far as I'm aware, no 12.5 khz channels were ever assigned.
In any case, that Icom got nicked from the flying club at Redhill when I left it there by mistake; thing is I'd still got the battery as I'd used the radio itself in a microlight which already had one, so it was of little use to whoever nicked it!!

[Whopity]

8.33 was a non industry standard Botch. after 12.5 it would be 6.25, which works for digital modes and NBFM but requires one sideband to be suppressed for AM. Not sure how they intend to accomodate offset transmitters which still require 25 KHz receiver bandwidth!

[riverrock83]

In the UK, OFCOM charge airfields less for 8.33 frequencies than 25kHz frequencies so there are a few around (Cumbernauld near me for example). However last time I was in that area - Glasgow asked me to call Cumbernauld on the 25 kHz version anyway.

The reason for 8.33 was so that you could replace each 25 spaced frequency with 3 new ones - so to try and future proof.

8.33 is complicated by what you select on the dial doesn't match what your radio receives / transmits over, so it is backwards compatible with offset frequencies (such as those used by 121.5 and London / Scottish Info).

If you select an old 25kHz channel on the radio, it receives in a 25kHz spacing on the frequency you have set. eg select 135.000 and it will use the 25kHz band, just like before.
If you select a new 8.33kHz channel is receives in an 8.33kHz spacing, but works out the correct frequency to listen to. eg 135.005 listens / transmits on 132.000 but with the narrower spacing.

And I don't know what you mean by non-industry standard, as this is the standard that they created :}

[Whopity]

And I don't know what you mean by non-industry standard, as this is the standard that they created The Telecoms Industry normally decides chanel spacing based upon available technology, to ensure compatibility between systems and services and to allow manufacturers to make suitable compatible components. 8.33 was dreampt up by Eurocontrol without reference to anyone else.

[chevvron]

The Telecoms Industry normally decides chanel spacing based upon available technology, to ensure compatibility between systems and services and to allow manufacturers to make suitable compatible components. 8.33 was dreampt up by Eurocontrol without reference to anyone else.
Eurocontrol? Not the ITU or ICAO?