Questions about alerts during close encounter with Ikarus

[Young_C]

Hi All,
I made a flight yesterday to Skegness, and PilotAware gave a great improvement in situational awareness. I had a close encounter with an Ikarus C42 (G-JENK) near The Wash, see video below:

https://youtu.be/hfj9Ky92FrE

I have a couple of questions about PilotAware's operation:

1. I have set the Vert Disp Range to +/- 1000' but still got audio alerts outside this range, e.g. at 0:45 on video there is one at 1200' below. Any ideas why? (I've noticed this on other occasions when flying over airfields, it seems to warn about traffic on the ground far below my level, which is a bit annoying, it would be useful if these could be suppressed.)

2. The Ikarus tracking disappeared at close range (1:17) and reappeared (1:35). I'm not sure why, perhaps the starboard wing blocked the reception to the ADS-B antenna?

Thanks,
Chris.

[Deker]

I'm wondering why you didn't make an early alteration to your course so you didn't have a close encounter with Ikarus in the first place?
Isn't that the whole idea of electronic conspicuity!

[Young_C]

I was testing the system and had the traffic in sight throughout so didn't need to change course.

[exfirepro]

Hi Chris,

Re your earlier post...

Have you read the section in the Operating Instructions about PAW’s Visual and Audio Alerts? If not, please do so. You can find the information on pages 28 - 30 of it here...

https://pilotaware.com/Documents/Operating%20Instructions%2020190621.pdf?_t=1561197960

For ‘known position’ aircraft (i.e. PilotAware, ADSB, or FLARM/Mode-S/3D Rebroadcast), Audio Alerts report the aircraft’s position as it ‘breaks in’ through any of the boundaries of one of the three warning cylinders around your aircraft. These alerts are then repeated if the aircraft continues to close with your own either horizontally or vertically.

For ‘Bearingless’ Traffic i.e. pure Mode-C or Mode-S transponders, with no ‘range’ data the alerts are given in a different format, indicating degree of perceived risk and relative altitude, such as ‘Traffic Notice 500 feet below’. Whether or not you receive these alerts depends on your ‘Mode C/S Horizontal Sensitivity’ and ‘Mode C/S Vertical Display Range’ Settings on your PilotAware / Configure Screen - (see pages 13 - 14 of the Operating Instructions).

In your video, the first ‘Bearingless Target’ alert - at 0.46 reports a fairly strong signal (hence ‘Danger’) from 1000ft below. This alert wasn’t preceded by a typical ‘Notice’ or ‘Alert’ warning as the aircraft approached and is typical of a first alert from a high power CAT transponder - probably from an aircraft on the ground at a nearby airport. The following report ‘Notice’ at 1200 ft below indicates that the risk is reducing - because you and the aircraft are moving apart (I’m guessing you had your Mode C/S Vertical Display Range set at +/- 2000ft). You can reduce the likelihood of these high power alerts by reducing your ‘Mode C/S Horizontal Sensitivity’, but this will also reduce warnings from closer GA aircraft, so better IMO to learn to recognise this ‘signature’ - i.e. a sudden ‘Danger’ warning without a prior ‘Notice’ or ‘Alert’ message as High-Power CAT at distance, which you can generally ignore PROVIDING THE REPORTED RELATIVE ALTITUDE ISN’T CLOSE TO YOUR OWN.

Edit: I meant to add - the Traffic ‘disappearing’ at close range as it passed behind you was almost certainly due to screening between your two aircraft’s antennas which can be caused by aircraft engines, bodywork, undercarriage, pilot and passenger bodies or simply sub-optimal antenna placement in either aircraft.

Other than that, the system has done exactly what it was designed to do.

I hope this helps explain what was going on.

Regards

Peter

[Young_C]

Hi Peter,
Thanks for your response.

Yes I've read the manual, my question relates to the Modes C/S Vertical Display Range settings on p14. Although I set this to +/- 1000', I still get alerts outside this range, in this example the 'Notice' at 1200'. FYI I've attached a screenshot of my settings.

Based on your explanation, could it be because the original 'Danger' detection was within this range and PilotAware continues to report it as the traffic moves out of range subsequently?

Also thanks for your comment about the close range screening, which makes sense.

Best Regards,
Chris.

[exfirepro]

Hi Chris,

Yes, that’s certainly the most likely explanation in this case. There are still certain other anomalies with audio reporting, one of which I did notice in your video and to a much greater extent during a couple of my own recent flights in tandem with another aircraft, which I need to work through with Lee when he gets the time, but as your video shows, all seemed to work fine as far as alerting you to the converging aircraft and helping you avoid a potential airprox (or worse). Best of all, except for glancing at your PAW Radar Screen, you were able to remain ‘eyes out’ for most of the time.

Best Regards

Peter

[Admin]

Chris,

Can you provide the track file, this may have been a Mode-S/3D rebroadcast, and you were on the edge of a receiver
I can probably tell from the track contents

thx
Lee

[Young_C]

Hi Lee,
I've uploaded the file to Aircrew and made it a public flight. However I cannot see it on the list, the filename is 2020-07-17_10-24.trk

It is 10.17MB so too big to attach on this forum. If you cannot see it on Aircrew please give me your direct email and I can send it to you.

Thanks,
Chris.

[Young_C]

BTW the Aircrew site shows this number during playback:
592ab71e