On Sunday, January 10, 2016 at 12:57:03 AM UTC-5, smfidler wrote:
XC,

Again, you assume the flawless function of the Flarm system. 25 seconds, if the Flarm "network" is not perfectly functional due to say structural interference, may be reduced to 5 seconds. Or zero. Arbitrary discussions about were "safety ends" and "philosophical Flarm fairness?" (whatever the hell this should be) begins has proven quite frightening to observe.

The longer the time period the Flarm has to make a potential warning (beep as "bogey" appears), the better. This is a fact (from a safety viewpoint). Artificial reductions in Flarms engineered performance potential will by definition also increase the odds of a dangerous situation occurring. While being far better than nothing, the Flarm network is still prone to regular coverage challenges and clearly does not have, perfect, 100%, 360 degree coverage at all times. Far, FAR from it.

We need to kill this whole idea for at least one year. It's out of control. It is irresponsible (at best) to screw around with Flarms potential range at this point. The unintended consequences are potentially huge. The philosophical competitive "fairness" argument is simply no peer to safety. It's not even on the same planet as safety. Stop treating this discussion like this as a debate between equals. Start respecting the fact that Flarm, while valuable for safety, is far, far from perfect or infallible. So when you say a supposed time value that you find acceptable for your little crusade, imagine that the gliders 25 seconds away from a potential collision are not seeing each others antenna at 25 seconds for whatever reason. Or maybe you get a proximity "beep" and then lose coverage for 15 seconds.

Bottom line, some here care far more about philosophical fairness arguments than the significant safety value Flarm provides via its ability to create situational awareness for us. This crusade become an literal obsession for some.

I won't debate or compromise Flarm at this point until some sort of impartial, objective study (and extensive testing) has been completed. This was the requirement of my initial support for a limitation. Since then, the almost reckless abandon that many supporters (almost certainly coordinated in a pseudo RAS Flarm "mode" campaign) have demonstrated here is a real problem. The USRC opinion poll does not support this desperate position.

Perhaps the FAA should be involved. Has anyone discussed this topic with the FAA? I wonder what their take would be.


I was just pointing out some of the time values involved in operating with TCAS. I suspect that research was more extensive and the technology is more proven. Many TCAS resolution advisories occur before they are displayed as targets on the screen. The pilot's eyes are directed to the display (on the VSI in our case) to make a correction because it is a system used during IFR.

With FLARM the eyes are directed outside as they should be. The best way to do this is through the audio warning system. More could be done with this to improve safety. For example, there could be a warning "Multiple traffic, One o'clock high." This is another real suggestion that would enhance the FLARM system. The TCAS time values are real numbers to add perspective to the discussion.

XC