What are the criteria for the colours white/green/amber/red in terms of vertical and horizontal separation?
Kind regards
C.
Hi ‘C’,
That’s a bit more difficult to answer as it depends on several different things.
If, as you say, you have read the PilotAware Manual, you will be aware that there are two types of notifications - for ‘Known Position’ and ‘Bearingless’ Targets and traffic data is sent to the Nav System accordingly. The first point I would make is that the
Relative Altitude of the other aircraft (in relation to your own) is
always reported - both in the audio alerts and on-screen - next to the aircraft symbol for ‘Known Position’ aircraft, and at the 12 o’clock position on the ‘Ring’ for ‘Bearingless’ targets.
If you are referring to the coloured rings for ‘Bearingless’ targets,
these do not denote distance (either vertical or horizontal), but are an indication of ‘Degree of potential danger’ based primarily on strength of received signal from the target aircraft’s transponder. This in turn will be influenced by the output power of the transponder and will also be affected to a varying degree by the antenna installations in
both aircraft and the relative orientation of those aircraft to each other. The ‘distance’ at which these warnings are triggered is also governed by your chosen Mode CS Horizontal ‘Range’ setting in PilotAware/Configure. You should also be aware that high power (CAT) transponders can transmit Mode-S at up to 500 watts, which will over-ride the preselected range selection and can cause the rings to go rapidly through green/amber/red - or straight to red, often when still outside visible range - unless you have ‘Ultra-Short Range’ selected. There is no easy solution to this problem, but you will soon get to recognise the distinctive ‘signature’ of this type of traffic.
In practice, it is a case of preselecting a range setting (I usually suggest Medium Range) and getting a feel for the distances reported in your aircraft. Users will often then opt for a shorter reporting range.
For a number of reasons, PilotAware has always been against trying to provide ‘anti-collision’ warnings, preferring instead to provide information to the Pilot, who can then make their own decisions. SkyDemon, however,
has developed their own ‘anti-collision warning’ algorithms,
for ‘Known Position Aircraft’ by calculating danger of collision from the position and direction of both aircraft. This triggers the colour changes for visible (on screen), moving, ‘Known Position’ Aircraft and associated visual ‘Banner’ alerts when using their system. White aircraft represent ‘No Perceived Risk’. The aircraft then changes through Green/Amber/Red if a ‘potential’ collision risk is identified and increases. I can’t however provide any other info on the specifics, and suspect that SkyDemon won’t divulge details for reasons of commercial confidentiality. With experience, however, you can probably work out approximate ranges and bearings for yourself. Suffice to say that in my experience over several years of use, both sets of ‘warnings’ are pretty reliable.
Hopefully this helps clarify things.
Best Regards
Peter