Primarily for general aviation discussion, but other aviation topics are also welcome.
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By PaulB
Just looking at the latest batch of airport reports are there are 5 airproxes involving survey aircraft ... uary-2020/

Two recommendations are made:

1. The P68/C404 operating company considers further mitigations to MAC for survey operations.

2. The CAA to consider mandating additional cockpit crew to enable enhanced lookout for single-pilot survey operations.

There's also an airport where traffic info derived from PilotAware (as part of a trial) was given by an AGCS to avoid a conflict ... 019220.pdf
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By Rob P
Turweston recently became (rightly) exercised about a survey aircraft operating in their area with a blanket NOTAM that could have led the unwary into thinking Turweston was unavailable, which then spent the day surveying without once giving Turweston a call.

Obviously no compulsion on the to speak to an airfield several thousand feet below them (ISTR they were at 5 or 6,000 ft), but politeness / airmanship?

Rob P
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By GrahamB
It was probably the case that the PAW was the position source for a Mode S -ES transponder, so yes, it would have been ADSB.
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By gaznav
I believe that the Cessna 150 would have been SIL=1 or better? This is because the Cessna is a certified aircraft and so needs to use a certified GPS for its Mode S ES transponder? [edit - not correct - see @wigglyamp ’s post below this :thumright: ]

The North Weald AGRO was using one of the Airspace 4 All trial set ups which is not provided by Pilot Aware as the original post by @PaulB mentions - reference: ... -may-2019/
[Edit, the trial uses uAvionix PingStation receivers: and the free Virtual RADAR Server (VRS) software]

The most interesting thing for me is that the Quik Pilot did not notice the Pilot Aware warning - it states in the notes: “ The Quik pilot subsequently confirmed that although he did not remember seeing the traffic on his PilotAware at the time, he has since downloaded the flight log and can see that it did in fact alert, but was a bearingless target and only displayed for about 10 seconds”. So if the C150 was emitting ADS-B that North Weald could see then why did the Pilot Aware only display a bearingless target?

The Airspace 4 All kit saw the Cessna’s ADS-B so why not the Pilot Aware? This is what the AGRO said:
“ THE NORTH WEALD A/GO reports that he was keeping an eye on the ADS-B Traffic Display as part of an Airspace4all trial, ensuring that the equipment was working as it should. There were several training aircraft in the circuit, all with ADS-B SkyEcho equipment on board. During the C150’s climb- out he happened to look over at the display and noticed that there was ADS-B traffic approaching from the west, indicating 100ft above the circuit height (1200ft QNH). In line with the AIC document that was published as part of the trial, he gave Traffic information to the C150 pilot informing him that there was ADS-B traffic approaching from the west not on frequency. The instructor confirmed that he was looking, but was not visual. The AGO proceeded to give a position report in relation to known local reference points. As the C150 climbed into the crosswind leg of the circuit and reached circuit height (indicated 1300’ QNH on ADS-B TD) he became visual with the unknown traffic at a range of estimated 300m. The instructor took avoiding action by commencing a level right turn towards the southern boundary of Stansted CTA which is located approximately 1.5nm north of North Weald Airfield. Once clear of
the conflicting traffic, the C150 continued their circuit detail without further issues. ”

It’s a shame that the UKAB didn’t dig a little deeper on this one. Good work by the North Weald AGRO, though :thumright:
Last edited by gaznav on Sat Feb 15, 2020 8:50 pm, edited 1 time in total.
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By wigglyamp
gaznav wrote:I believe that the Cessna 150 would have been SIL=1 or better? This is because the Cessna is a certified aircraft and so needs to use a certified GPS for its Mode S ES transponder?

This isn't actually correct. Under EASA CS-STAN, you can connect an un-certified GPS source to a transponder in a certified ELA 1/2 aircraft and radiate SIL-0 ADS-B, as was done during the earlier UK LAA trial.

Standard Change CS-SC005a

1. Purpose
This SC is for the installation of ADS-B OUT systems. This SC allows the embodiment of different configurations for the voluntary transmission of ADS-B data (e.g. GPS position and velocity).
This SC addresses three cases:
Configuration 1: an ADS-B OUT system that conforms to AMC 20-244; — Configuration 2: an ADS-B OUT system with an ETSO-C199() GNSS position source;
Configuration 3: an ADS-B OUT system with a GNSS position source that is not approved.
Note: The aircraft identified in the applicability/eligibility section of this SC do not need to comply with Commission Implementing Regulation (EU) No 1207/2011 or its later amendments. Consequently, they do not need to satisfy the requirements set by CS-ACNS Subpart D Section 4 ‘1090 MHz Extended Squitter ADS-B Out’.
The likelihood of erroneous data being transmitted to ADS-B ground stations and to other aircraft is defined by quality indicators.
Configuration 1 installation provides quality indicators according to the principles that are defined in AMC 20-24 while controlling the latency through a direct connection between the transponder and the GNSS position source. — Configuration 2 installation provides quality indicators that are defined in ETSO-C199.
Configuration 3 sets the quality indicators to zero (0). Operators of aeroplanes fitted with a configuration 3 installation are expected to use the system for traffic awareness only. Equipment emitting with quality indicators that are set to 0 might not be seen by other aircraft systems or by ATC.
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By PaulB
gaznav wrote:Thanks @wigglyamp - edit comment added :-)

When I get a min, I'll edit my original post too. :-)
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By patowalker
What makes you think the Cessna was ADSB equipped? English is not my first language, but when I read that report I see nothing to indicate it was.

It seems to me that Pilot Aware was the key to the C150 taking avoiding action.