Voice Alerts from P3i PAW target

[Moffrestorer]

Hi Lee,

Having installed PAW behind the panel of our Eurostar yesterday, with external stub antennas from PilotAwareHardware for P3i and ADSB mounted on the stbd underwing to fuselage aluminium "fillet", I went to fly a couple of circuits just before it got dark.

There were 2 aircraft in the vicinity and I was receiving voice alerts from them. I didn't have my tablet with me so no visual indication, only the audio! Both aircraft landed in turn but I noticed that the "clock" alerts that I was getting from the gyrocopter that is equipped with a PAW, whilst correct in relative heading and distance, were being given as "level" (with me), even though he was now on the ground and I was about 1000' above and about 4 km away. This is presumably lower than the + or - 20 degree "level" detection window. Shouldn't the alerts have been saying 10 o'clock LOW, 4 km?

Incidentally, I was amazed how much better the external stub antenna was at pulling CAT traffic in from even greater distances, than the whip supplied with the TV tuner dongle, even though it's still not optimum length for 1090mhz.

[Deker]

Hi,

1000ft is 305m high and at a range of 4000m the angle would be 4.36 degrees, so "level" would be the correct audio report.... I think :-)

ATB
Deker

[Admin]

Hi Chris
Deker is correct, i thing the implementation is +/- 15 degrees is classed as level.
We are thinking of changing this to report the relative height difference, Would this be better ?
I am very interested in comments about the reporting message, because this issue is raised frequently

Thx
Lee

[Moffrestorer]

Hi Lee and Deker,

Oops! Just after making the above post, I thought I should work the angle out, then had to go out.

When you're in the circuit, fairly tight in, the angle down to the airfield just looks so much greater than a paltry 4 degrees*. Anyhow please accept my apologies.

I do feel that relative height difference would be preferable within the current audio alerting system than High/ Level /Low  classifications that we have at the moment. Seems somehow easier to contextualise.

What do others think?

Thx,

Chris

Edit: This approximates to the normal glideslope, so goes to show how different things can appear!

[Arcticash]

Hi Chris
Deker is correct, i thing the implementation is +/- 15 degrees is classed as level.
We are thinking of changing this to report the relative height difference, Would this be better ?
I am very interested in comments about the reporting message, because this issue is raised frequently

Thx
Lee

Hi Lee and Deker,

Oops! Just after making the above post, I thought I should work the angle out, then had to go out.

When you're in the circuit, fairly tight in, the angle down to the airfield just looks so much greater than a paltry 4 degrees. Anyhow please accept my apologies.

I do feel that relative height difference would be preferable within the current audio alerting system than High/ Level /Low  classifications that we have at the moment. Seems somehow easier to contextualise.

What do others think?

Thx,

Chris

I would personally have expected "Level" to be say within a set hight eg. 500ft vertically of current altitude and then LOW or HIGH to be anything outside of that range, however this might just be me interpreting things differently, i can certainly see why a funnel type system of +/- 15 deg. could be useful too

Ash

[efrenken]

...
I do feel that relative height difference would be preferable within the current audio alerting system than High/ Level /Low  classifications that we have at the moment. Seems somehow easier to contextualise.

What do others think?

Thx,

Chris

Chris and others,

My vote, if I had one, would be for "clock direction" (don't know the usual expression at the moment), distance and relative height difference.

Best regards

Eric

[exfirepro]

Having installed PAW behind the panel of our Eurostar yesterday, with external stub antennas from PilotAwareHardware for P3i and ADSB mounted on the stbd underwing to fuselage aluminium "fillet", I went to fly a couple of circuits just before it got dark.

I was amazed how much better the external stub antenna was at pulling CAT traffic in from even greater distances, than the whip supplied with the TV tuner dongle, even though it's still not optimum length for 1090mhz.

Hi Chris,

In actual fact the P3i antennas - tuned to 869 MHz - are still 'longer' than the optimum length for 1090 MHz (higher frequency = shorter wavelength) and as yours are fitted 'out in the clear', I would expect them to perform better for both systems.

On the question of traffic reporting, - my tuppenceworth, FWIW - I would also prefer traffic reports to report 'relative altitude', rather than 'level', which despite understanding the principle, I still find very inaccurate and of little help in advising me where the aircraft actually is in relation to me. I can understand and accept 'High' or 'Low', but when level is anything but, the information it provides is in my opinion potentially dangerous!

Regards

Peter

[Ian Melville]

Another vote for relative altitude.

[rogerabc]

Hello,

Just writing to add my preference for "relative altitude".

[T67M]

I'd vote for brevity with high/level/low - but accept that "level" must be +/-100ft or closer.

The problem I see with giving the relative altitude is that it's just too wordy - the PAW audio alerts at the moment are something like "two thousand three hundred feet below" and take about five seconds to speak, with the most critical word (below) right at the end. The difference between 200ft below and 2,300ft below is irrelevant to me as a pilot - I just need to know to look at the ground not the sky! It might be useful to know climbing/descending though.

[exfirepro]

Mike,

Climbing/Descending is coming - at least 'on screen'. The work to produce the arrows has been done and tested and is due to come out in the next PAW release, together with aircraft 'type-specific' icons. Unfortunately at the moment the climb/descent arrows will only show on SD for 'moving' targets (ADSB and P3i) , though we have been promised by SD that their protocols will be re-written to accommodate the arrows for 'bearingless' targets at the earliest opportunity.

Personally, I would also like climbing/descending information added to the audio alerts for bearingless targets within say +/- 500 feet of me, though I do appreciate we still have work to do to reduce the intrusive impact of excessive bearingless target audio alerts, hence Lee's request for opinions.

Regards

Peter

[peteD]

"Relative height" please, as this would be factually correct(excepting system errors), This is what is given on TCAS display, although the aural alerts are different because it gives avoiding action, which is beyond the scope of PAW

By Saying "level" when it clearly may not be, is devaluing the warning.
regards
Pete

[rogerabc]

If you can't see or don't know the position of conflicting traffic then the only deconfliction strategy is to climb or descend.
To do this you need to know the altitude of the other traffic relative to you.
That's what TCAS does.

Roger

[Admin]

Please bear in mind that the calculated altitude will be based on either
GPS, onboard Baro, or Transponder Baro

All of these have accuracy issues, for example in the case of a mode C transponder it is rounded to the nearest 100ft

So the idea behind the Audio is to prompt for a visual scan, and a screen confrimation

thx
Lee

[exfirepro]

Please bear in mind that the calculated altitude will be based on either
GPS, onboard Baro, or Transponder Baro

All of these have accuracy issues, for example in the case of a mode C transponder it is rounded to the nearest 100ft

So the idea behind the Audio is to prompt for a visual scan, and a screen confrimation

thx
Lee

In my experience most reported altitude inaccuracies are generally considerably less than 100ft and in any case, reporting relative altitude audibly - even with slight inaccuracies - is still MUCH better IMHO than a report of 'Level' when the aircraft may in fact be above, level with or below you - especially in the case of bearingless targets where we have so little to go on. Much better to hear an audio alert and be in a position to scan outside immediately before taking up potentially valuable time checking for relative altitude on screen.

Regards

Peter