RC madness
On Wednesday, December 23, 2015 at 12:28:10 PM UTC-8, wrote:
On Tuesday, December 22, 2015 at 7:50:19 PM UTC-5, jfitch wrote:
On Tuesday, December 22, 2015 at 2:15:16 PM UTC-8, wrote:
SNIP Not trying to be difficult but I must be missing something. If they're that close to you (i.e., within 2 km), they're visible even with Stealth.
From the Flarm documents, V6.0 page 19 (maybe this has changed?):
"Targets with enabled “Stealth Mode” are only displayed..... if they meet at least one of the following requirements:
- target is a threat
- target is within 100m horizontal and 50m vertical
- target is within 2000m horizontal and 300m vertical and within ±45° of own flight track."
So the guys going your way - the ones ND is going to pull up sharply into - you don't even know are there. They aren't a threat because they are paralleling your course. Even if they are close enough to appear, their relative altitude is intentionally wrong.
Now I am going to repeat for the 20th time or so, I don't believe Flarm is a huge increase in safety. It is a big sky and most accidents are spin/stall, not head on. I don't even call my Flarm an anti-collision device, I call it an in-flight entertainment system. But certainly beyond a doubt, it improves situational awareness always, and particularly in the scenario described. On The White Mountains and the Sierra convergence lines, I don't think there have been any head-ons than I can recall. Its a big sky. But plenty of people have had to change their underwear at the end of the day, I can assure you. It was enough of a concern that a rather elaborate procedure was devised in the area, reserving a radio frequency and involving reporting points etc., all of which seemed pretty ineffective, while non-stealth FLARM pretty much solves the problem completely and with no distraction.
From your experience, at about what distance does Flarm give conflict alert in a high speed head on situation? I understand that some gliders show on display at "long" range, presumably before alarms go off by some amount. I'm trying to get a practical understanding of the best case sensing and how it compares with alarming.
Anyone with real world experience, please ring in.
Thanks
UH
I have never had an unexpected head on warning. The expected ones seem to happen about as claimed, around 12 - 15 seconds prior to impact. The reason I have never had an unexpected warning is that any glider with non-stealth Flarm shows up on the tactical display many miles out - at least 5 and often 10 or more. Most gliders flying in this area fly with non-stealth Flarm. I consider unexpected warnings to be a direct result of loss of situational awareness, after which one should evaluate what he/she is doing wrong.
Prior to Flarm, flying a very fast narrow street like the White Mountains, it was not at all uncommon to have a glider flash by going the other way maybe a few wing spans apart, with 2 - 3 seconds from visual recognition to passing. You are looking for a nose-on white glider against a white cloud background. No doubt there were others that I never saw. With Flarm, you see MANY more gliders that you never would have seen, and close crossings are easily avoided.
Now I will pre-empt the responses about head down time. I consider the Butterfly and other dedicated Flarm displays to be quite deficient for tactical, situational, and collision avoidance use. I don't have one. Flarm targets appear on the moving map tactical display at all times, and are emphasized on that display if the get close. A one second glance is more than enough to evaluate the whole fleet. The vario has voice warnings for collision threats of both gliders and GA aircraft. It does not add to heads down time.
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