Lowering Class E between Melbourne and Cairns

[jackc]

No matter what happens with the new proposal,  I will be better off with. Skyecho EC device, than without one.....

[RFguy]

My SkyEcho2 in my TEM cell at my lab, measuring  sensitivity , and antenna alignment sensitivity .  I need to write some more Mode S-ES waveform code, since the airspace above me has nothing to listen to (record and play back into my system) . 

 

 

[SplitS]

ADSB broadcasts about every half a second this is faster and more accurate than Transponders "C"

Why is the FAA transitioning away from radar and towards ADS-B technology?

https://www.faa.gov/nextgen/programs/adsb/faq/#g1

Transponders are going to be phased out it makes no sense to lower class G airspace until they sort this out in OZ.

[RFguy]

Hi Splits. Good link you posted.

Yeah, random between 0.4 and 0.6 seconds for a ModeS-ES device. Well Mode C transponder of course does not 'broadcast' it only responds when pinged, and when by an SSR - about once every 4 seconds when the radar beam comes around . (15 RPM) .

 

 

[rhtrudder]

I wonder where Dick Smith stands on these changes 

[Student Pilot]

Superfluous really, there will be no GA left shortly to transit airspace. 

[Old Koreelah]

Many of we rec. pilots have little understanding of all the different types of equipment- transponders, Mode A,B,C,S, ADS-B, SE2...

Is this just the perfect way to confuse the flying fraternity and the wider public?

 

Perhaps some knowledgeable person can point me to an easy-to-understand outline of the different technologies, which ones are favoured by the authorities and their approximate cost.

 

[horsefeathers]

Official CASA response to use of SkyEcho 2 in Class E

 

I asked a CASA rep if they could get a clarification of CASA's position re use of SkyEcho2 in Class E, as a substitute for a transponder.

Here is the email trail, my questions (in italics), and CASA's response in green. It has been anonymized.

 

========================================= email trail ========================================

OFFICIAL

 

Good morning xxxxx,

 

I have received a reply, (in green), from the Senior Standards Officer, Air Traffic Management systems, of the Flight Standards Branch for you.

 

• From my reading of the manufacturers website, https://www.uavionix.com.au/skyecho2. This is a portable ADS-B In and Out , and has been accepted by CASA as an approved Electronic Conspicuity (EC) Device as an enhancement to "See and Be Seen" from 16th July, 2020. It is NOT a transponder.  

“Correct, with more information about electronic conspicuity and ADS-B is available on the CASA website (https://www.casa.gov.au/airspace/electronic-conspicuity-devices ) as well as in this Advisory Circular: https://www.casa.gov.au/files/advisory-circular-91-23-ads-b-enhancing-situational-awarenesspdf .”

 

• .......   I am assuming that CASA intended these devices to be used in Class E in lieu of transponders, to improve visibility under 10,000 ft to VFR aircraft.

“While a SkyEcho 2 improves visibility and situation awareness in Class E airspace, it would have to be used in this airspace in conjunction with a transponder. It cannot be used in lieu of a transponder. The main reason CASA does not allow the SkyEcho 2 to be used by itself in Class E airspace is because it does not respond to TCAS interrogations.”

 

• These SkyEchos are very popular and have also been approved for use in the United Kingdom (where their CASA equivalent is subsidising the purchase of these units.

“This is precisely why EC devices like the SkyEcho 2 were adopted for use in Australia. Unfortunately, CASA is not funded to subsidise their purchase.”

 

• I would like to strongly press for a change to allow carriage of a suitably configured Sky Echo to meet the equipment requirements for Class E up to 10,000ft. The current proposal is a safety disaster in the making.

“The main reason the SkyEcho 2 is not suitable is that it does not respond to TCAS interrogations. TCAS is an important last-ditch safety mitigator for any larger passenger aircraft that may be operating in Class E airspace. Another problem is that the SkyEcho 2, as a portable windshield-mounted device with internal antenna, can suffer from shielding from an aircraft’s superstructure. This means its transmissions are not as reliable dependable as a transponder or other ADS-B device (fixed or otherwise) that has a proper external antenna.”

========================================= end of email trail ========================================

 

Anyone got a cheap transponder I can buy?

 

 

 

 

Edited February 7, 2021 by horsefeathers

[RFguy]

yep. exactly. That's why I have been going on about a Mode A transponder and a skyecho.

 

[Kyle Communications]

HF...I wouldnt be to concerned about rushing out and getting a transponder thats for sure.

This Class E clusterf**k will not get up because it is even too far ridiculous for even someone like CASA to approve. Save your pennies...well at this stage

 

[RFguy]

You can get a microair for about $500. The microair transponders seem to be pretty good and reliable, compared to their radios...

 

Or you can get a 2nd or 3rd or 4th hand old KT74/KT76 for a few hundred dollars.

Don't bother with the altitude encoder requirement at the moment..

Or a nice  GTX327 etc for 600-900$. .  

Budget about 1 amp or so from the 12V system to run it.

-glen

[walrus]

transponders roughly $3500 each for ?2000 RAA aircraft? Plus installation. $6 million?

[jackc]

6 minutes ago, RFguy said:

yep. exactly. That's why I have been going on about a Mode A transponder and a skyecho.

 

Well, I am not going to go out and buy some old relic Mode A transponder,  worse than relying on old secondhand past EOL radios......

Edited February 7, 2021 by jackc
Word spacing

[RFguy]

Yeah I would steer away of the old tube amplifier ones . There would be few that know how to fix them. (I do but they are hard to get parts for) . I would suggest something made in the last 25 years.....

Construction and quality is very good. I have inspected a bunch of 30 to 35 YO Bendix  types and they clearly had good quality control in their manufacture. The problems I have seen are related to.... poorly performed repairs , usually to components subject to voltage spikes.

[facthunter]

If I recall correctly, they require shielding to the occupants to be installed. Nev

[jackc]

3 minutes ago, RFguy said:

Yeah I would steer away of the old tube amplifier ones . There would be few that know how to fix them. (I do but they are hard to get parts for) . I would suggest something made in the last 25 years.....

Construction and quality is very good. I have inspected a bunch of 30 to 35 YO Bendix  types and they clearly had good quality control in their manufacture. The problems I have seen are related to.... poorly performed repairs , usually to components subject to voltage spikes.

I sadly see stuff for sale on Facebook Avionics and Aircraft Sites that are from questionable sources, private sales names that come up often, flippers etc.  Probably junk from overseas and resold here.

No guarantee they will be reliable, many EOL components?

i would only buy from someone I know or good word of mouth referral.
 

[WayneL]

On 07/02/2021 at 7:56 AM, rhtrudder said:

I wonder where Dick Smith stands on these changes 

Have seen a letter that Dick wrote to the Deputy Prime Minister and Transport Minister. He is on the GA (& Raaus) side. He is asking for them to look at the USA E class airspace more closely, says the proposed change here is unworkable.

Waynel

[RFguy]

Hi Nev. Not according the the governemt instrument 

The pilots are really "occupational exposure class" but there is a bit of an argument there, so we will take the "General Public Limits", as the plane may carry passengers.
From Arpansa RPS3  Schedule 3 : 45 V/M averaged over a 6 minute period or 1434 V/M Instantaneous max , or 5500W/sqM plane wave equiv Instantaneous max .
We use the Instantaneous max because the average over 6 minutes is miniscule...(duty cycle < 0.00024 %)
A 250W transponder, radiating into a notional dipole antenna, at a distance of 30cm,  will be at the worst case orientation, 357 V/M, or 1/4 of the peak permissable.
At 1 meter distant, will be 109V/M , 1 fourteenths of the permitted levels.

 

If in a circraft with non conductive skin,  I would suggest a minimum distance of 1 meter to permit better transmission and reception charactistics.

Levels > 20V/M may still generate a pop into a intercom system if shielding of the intercom is poor. That's because intercomes etc are generally poorly shielded. 

The minimum distance of a transponder antenna from a VHF com antenna should be at least 1 meter, to avoid generation of interference pulses and or giving the radio a fright every time the transponder goes off...

 

-glen

 

Edited February 7, 2021 by RFguy

[walrus]

.....and further reading of CAO 20..18 indicates No use of ADSB - Out from a mode S transponder unless it is connected to a $2000++ certified GNSS unit.

 

Then of course space based ADSB is coming which requires at least extra aerials. Then supposedly there is an Australian SBAS system which may require a different GPS.

 

And then we find that Sky Echo is just a toy as far as CASA and Airservices are concerned, and anyway airliners don't do ADSB, they do TCAS.

 

The entire ADSB thing is just a useless circus.

[RFguy]

Walrus's comments are not correct.
 

[kgwilson]

On 07/02/2021 at 10:57 AM, Old Koreelah said:

Many of we rec. pilots have little understanding of all the different types of equipment- transponders, Mode A,B,C,S, ADS-B, SE2...

Is this just the perfect way to confuse the flying fraternity and the wider public?

 

Perhaps some knowledgeable person can point me to an easy-to-understand outline of the different technologies, which ones are favoured by the authorities and their approximate cost.

 

An explanation of the different modes and what Transponders do is Here . As I mentioned elsewhere they were invested by the Poms in WW2 & originally called Parrot, hence when ATC ask you to squawk the code by pressing the Ident button it was originally  called "squawk the parrot." This is a radar based technology and it enables interrogation by ATC.

 

 ADSB stands for Automatic Dependent Surveillance Broadcast which uses GPS technology to determine position & height and broadcasts the aircrafts encoded details to ATC and other aircraft. ADSB IN/OUT broadcasts your aircraft details and receives details from other ADSB equipped aircraft and details are then interfaced to and displayed on the moving map of Navigation software systems such as Oz Runways Av plan etc. Full details and explanations of how it works is HERE .

 

SE2 is just the acronym for the Uavionix Skyecho 2  the portable ADSB in/out unit approved for GA use by CASA.

 

 

[kgwilson]

2 hours ago, horsefeathers said:

 

“The main reason the SkyEcho 2 is not suitable is that it does not respond to TCAS interrogations. TCAS is an important last-ditch safety mitigator for any larger passenger aircraft that may be operating in Class E airspace. Another problem is that the SkyEcho 2, as a portable windshield-mounted device with internal antenna, can suffer from shielding from an aircraft’s superstructure. This means its transmissions are not as reliable dependable as a transponder or other ADS-B device (fixed or otherwise) that has a proper external antenna.”

 

So they are blaming TCAS. Why did they design a system that relies on 75 year old technology. Of course it is the world wide standard for commercial aircraft and ADSB wasn't around then. The cost is somewhere between US$25k and $US150k per aircraft & only has a range of about 40NM. They are now up to TCAS IV with interfacing bells and whistles & of course it predates ADSB which has far greater range is modern GPS based technology & cheap to install in RPT & even cheaper for GA & RA.

 

TCAS is prone to errors relies on Mode C and has at least 15 major limitations. See https://en.wikipedia.org/wiki/Traffic_collision_avoidance_system#Drawbacks_to_TCAS_and_ADS–B

 

Also TCAS can interpret ADSB but as it is an old technology it doesn't have the capacity to read all of the data ADSB can send.

Relationship to Automatic Dependent Surveillance – Broadcast (ADS–B)[edit]

Automatic dependent surveillance – broadcast (ADS–B) messages are transmitted from aircraft equipped with suitable transponders, containing information such as identity, location, and velocity. The signals are broadcast on the 1090 MHz radio frequency. ADS-B messages are also carried on a Universal Access Transceiver (UAT) in the 978 MHz band.^[16]

TCAS equipment which is capable of processing ADS–B messages may use this information to enhance the performance of TCAS, using techniques known as "hybrid surveillance". As currently implemented, hybrid surveillance uses reception of ADS–B messages from an aircraft to reduce the rate at which the TCAS equipment interrogates that aircraft. This reduction in interrogations reduces the use of the 1030/1090 MHz radio channel, and will over time extend the operationally useful life of TCAS technology. The ADS–B messages will also allow low cost (for aircraft) technology to provide real time traffic in the cockpit for small aircraft.^[17] Currently UAT based traffic uplinks are provided in Alaska and in regions of the East coast of the USA.

Hybrid surveillance does not make use of ADS–B's aircraft flight information in the TCAS conflict detection algorithms; ADS–B is used only to identify aircraft that can safely be interrogated at a lower rate.

In the future, prediction capabilities may be improved by using the state vector information present in ADS–B messages. Also, since ADS–B messages can be received at greater range than TCAS normally operates, aircraft can be acquired earlier by the TCAS tracking algorithms.

The identity information present in ADS–B messages can be used to label other aircraft on the cockpit display (where present), painting a picture similar to what an air traffic controller would see and improving situational awareness.^[18][19]

[Thruster88]

I dont see why TCAS has to interrogate newer ADS-B transponders and EC devices that transmit continuously without being "pinged". Old mode C don't transmit unless they are interrogated. Perhaps RFguy could explain if an EC device would or could be made to work with modern TCAS.

[kgwilson]

38 minutes ago, Thruster88 said:

I dont see why TCAS has to interrogate newer ADS-B transponders and EC devices that transmit continuously without being "pinged". Old mode C don't transmit unless they are interrogated. Perhaps RFguy could explain if an EC device would or could be made to work with modern TCAS.

Agreed. This shoots down CASAs answer straight away. Interrogation is not required just readability of the pinged packets being sent which they can then display on their multi thousand dollar NAV screens & we can display their details on our tablet or phone. Airservices and CASA dinosaurs need to embrace the 21st century.

[RFguy]

When a Mode S transponder responds to a TACS or RADAR ping or 'all call' or specific interrogation , it will respond with the usual  Barometric altitude, Aircraft ID,  and airframe info. 

 

There is an additional unsolicited transmittion modes- that is broadcast,  call squitters,

 

There is a short squitter (DF11)  , it transmits these regularly for TCAS purposes.  When a TCAS capable airplane#1 hears the squitter from an aircraft#2 ,  it gets the ID of that plane  and  it then can do a direct interrogation of that ID , air to air  to determine distance from delay, and that airplane#1 can request  other parameters  from squittering plane#2.  

 

For Mode S-ES capable transponders: 

There is also a mode call 'extended squitter' (DF17) (ADSB)  includes position, status, velocity, opt barometric altitude, and other bigs and bobs.  Newer TCAS  systems can use the extended squitter information direction . Not all TCAS boxes out support this (ADSB-IN) .     The listening plane #1  does not need to interrogate the squittering plane#2 because the squittering plane#2 transmits all the information needed to provide TCAS function (3d position, status etc) in the 'extended' data packet.

 

This 'extended squiter' is ADSB !

 

Skyecho is a ADSB-IN box- listens to DF17 extended squitters, and it also generates unsolicited bursts ADSB-OUT DF17

 

The electronics in the Skyecho is pretty low tech, its not really capable I think of performing a time definite interrogation  reply.

 

 

 

Edited February 8, 2021 by RFguy