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CAA relaxes simultaneous transmission rules for transponders/ADS-B

https://www.gasco.org.uk/flight-safety-extra/flight_safety_extra_august_2019/caa_relaxes_ec_rules

“Mark Swan, Director of Safety and Airspace Regulation, announced in June that the CAA will be relaxing the rules around simultaneous transmissions from EC devices that meet CAP1391 requirements.

The move follows a set of tests using the devices and will initially cover Permit to Fly aircraft equipped and operating with Mode A/C and non-ADS-B compatible Mode S transponders.
The CAA will publish details for aircraft owners on how they can take advantage of the change in the coming weeks. The CAA said it will also be working with EASA to relax the rules around EASA aircraft.

By the end of the year, it plans to extend this freedom to all Mode S transponders that cannot readily be made compatible with ADS-B as a result of the new CS STAN changes. "

Since I now have ADS-B in on my plane, this will be very welcome!

Andreas IOM

What traffic system are you using?

Oxford (EGTK), United Kingdom

PilotAware Rosetta. It does a pretty good job receiving ADS-B transmissions (and I now have an Android phone with Skydemon that clips to the top of the instrument panel – so it’s just below the windscreen level so easy to look at, and gets connected to the audio aux in).

Last Edited by alioth at 04 Aug 20:00
Andreas IOM

What exactly is this scenario about (technically)?

Is it running a (obviously certified) Mode S transponder with an “uncertified” ADS-B OUT device (SIL=0) which transmits its own stuff without any linkage to the Mode S transponder? If that is the case then active-TAS + ADS-B IN systems will be unable to merge the two targets, because the merging algorithm uses the 24-bit ID. That would not be clever.

I would hope the ADS-B transmitter would at least pick up the 24-bit ID etc from the Mode S transmission (or have it user-configurable).

I can see why the CAA would want to relax this application scenario. There is a widespread belief that these low cost ADS-B gadgets help with inter-aircraft conspicuity, while any informed person will know that ATC can’t make use of SIL=0 emissions, but using Mode S makes you very easy to catch if you nip some airspace Under the new CAA infringement policy there is a lot of pressure to turn off transponders.

Administrator
Shoreham EGKA, United Kingdom

“Under the new CAA infringement policy there is a lot of pressure to turn off transponders.”
RUBBISH.
There is a lot pf pressure to stop people infringing. Nothing else.

Avionics geek.
Somewhere remote in Devon, UK.

Peter wrote:

Is it running a (obviously certified) Mode S transponder with an “uncertified” ADS-B OUT device (SIL=0) which transmits its own stuff without any linkage to the Mode S transponder? If that is the case then active-TAS + ADS-B IN systems will be unable to merge the two targets, because the merging algorithm uses the 24-bit ID. That would not be clever.

I would hope the ADS-B transmitter would at least pick up the 24-bit ID etc from the Mode S transmission (or have it user-configurable).

It’s mainly aim at running a CAP1391 device while running a mode a/c transponder or a mode s transponder not capable of ADS-B.
You are supposed to enter you ICAO hex address in the CAP1391 address.
The leading CAP1391 device is SIL=1.

So mode a/c + CAP1391 , no quick easy merge.
Mode S + CAP1391, merge should be possible (assuming the ADS-B transmission is not ignored because SIL=0 and certified receiver)

I can see why the CAA would want to relax this application scenario. There is a widespread belief that these low cost ADS-B gadgets help with inter-aircraft conspicuity, while any informed person will know that ATC can’t make use of SIL=0 emissions

AFAIK, there is no UK ATSU using ADS-B in except Aberdeen for the North Sea oil rig helos.

Nympsfield, United Kingdom
6 Posts
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