On Saturday, February 4, 2017 at 2:21:30 PM UTC-5, wrote:
On Friday, February 3, 2017 at 6:23:50 PM UTC-8, Tom BravoMike wrote:
If, theoretically, all those '10 or less in a gaggle' are equipped with ADS-B Out and In, and 'a good tactical display', will the information/warnings provided be still inferior to that of FLARM? Just curious...

Tom BravoMike

Yes, ADS-B will be inferior for a variety of reasons:

1) ADS-B doesn't do path prediction on the transmit side (straight, turning, climbing, descending, etc.). FLARM does.

2) ADS-B doesn't provide collision warning. For glider scenarios, this is almost impossible to do without some form of #1. At best a computer using ADS-B could give traffic alerts based on proximity, which for glider scenarios would generate a lot of false alarms if you tried to use it for anything beyond simple proximity alerts.

3) Most of the collision warning processing is done by FLARM, not the display. Imagine the challenges and confusion potential if each display used its own collision warning algorithm. Since there is no provision in the ADS-B specification for anything other than absolute position display based on GPS location. FLARM sends RELATIVE position and collision warnings to all displays so there is no ambiguity. In addition, there is no plan to provide this functionality that I am aware of across display manufacturers.

4) FLARM de-duplicates FLARM and ADS-B 1090ES and Mode-S transponder traffic based on ICAO ID. If you go a la carte, you would need to do this within each display. There are no plans that I am aware of to do this.

I'm sure there are other challenges. I do think it would be useful to MUX UAT (and possibly TIS-B) traffic into a FLARM NMEA stream, but it has challenges. I'd take whatever FLARM provides natively first, add a transponder second and then see if I need anything else, like ADS-B Out, TIS-B, UAT, or FIS-B (for weather radar, TFRs, etc - but that's a whole new set of display challenges).

9B

There is inherently no technical reason that an ADS-B based system can't provide just as sophisticated collision warnings as FLARM. Both systems rely on GPS position data transmitted once per second. I'm not an expert on this, but FLARM may transmit more predictive data that makes threat analysis in the receiver easier, but there is no inherent technical reason that an app connected to an ADS-B receiver can't track multiple threat targets and compute exactly the same trajectories that FLARM provides.

The BIG advantage of these ADS-B receivers is that they provide accurate position data for non ADS-B OUT, but transponder aircraft, received from ADS-B ground stations via TIS-B. Due to the half baked ADS-B IN implementation of PowerFlarm, which does not support TIS-B, transponder equipped aircraft can only be identified with an approximate range and altitude, so you have no idea if the target is in front of you, to the side, or behind you, nor which direction it is headed, etc...

Then of course PowerFlarm doesnt' provide weather radar, METARS, TAFs, and TFRs which are also standard with most ADS-B IN receivers.