This incident kinda ties into a dilemma that has been nagging at me since I started.
Is RTH the most appropriate "Fail Safe" response from a TX - FC system??
Given the number of GPS related fly-away/screw-ups and general advise to NOT fly in GPS mode, it seems a bit nonsensical to rely on this very mechanism when things turn to poo.
I can understand that a perfectly functional GPS and RTH combo is a great comfort BUT there are plenty of cases where this has either not worked or worse, actually caused an accident when mistakenly engaged (copter landed, suddenly decides that it needs to RTH and tries to get to 30m in a hurry)
So the only other option I have is to set my receiver to kill the throttle if the transmitter signal stops. I can't see any other way of stopping a thrashing copter, or dropping a craft heading into a dangerous area in the case of GPS failure.
There may not be a right answer to this but I'm really interested to hear what other think.
Charles.
IMO, a big part of the problem with this whole situation is that so many of these controllers that are more or less Plug and Play do nothing to educate their users, even advanced users, how these systems actually work. Worse than that, they actually obfuscate the situation, actively hiding what is going on behind the scenes from the user.
For example, the location this was shot at was a TERRIBLE location to use GPS. Same situation with the video last year with the skyscraper. If I was being paid to operate in that location, I would likely turn the GPS off completely, and fly in full manual mode. But that brings up the second and third problem with these systems. These systems do not tell their users they should learn to fly in manual mode. To do so, would be an admission that their system is fallible. It also hurts the idea that the system is easy to fly. Furthermore, many of them don't even *offer* a non-GPS flight mode! Something I read about the DJI A2 seems to indicate that their "Atti" mode still uses GPS! But just try and find out for sure from DJI!
Was this event caused by GPS problems? Who knows. Which is another problem, because users of these systems are not trained to figure out why it happened so they can *learn from their mistakes*, and/or the system designer does not give their users the tools to find out what happened.
I see this more and more, and it really frustrates me. People just buying their way into this industry, without any foundational knowledge whatsoever about how these systems work. It seems to me that most people think these things are endowed with black magic. I got interested in the industry 3 years ago, but I still haven't been paid to do a single shoot, because I'm still not at the point yet where I think the system is good enough. The problem there is that I know too much, and am a perfectionist.
The idea of carrying a towel around to throw over an errant copter, or a shotgun, seems insane to me. How often does this stuff happen? If you guys think that type of thing would make your operations safer, I really think you should have a second look at your systems and procedures. Can you imagine getting on an airliner and they hand you a parachute "Just in case something goes wrong". As I said, I've been doing this for 3 years, not just using the systems, but writing new code, etc. and I've NEVER wished I had a towel handy.
The fact that we don't already know exactly what went wrong in this case, 2+ weeks after the fact, is a demonstration the user and systems creator have both failed in some pretty fundamental ways.
And yes, it should absolutely possible to have these systems with an auto-land failsafe. That's what ours does. If you're flying in a GPS mode, and it suddenly looses GPS or has a massive GPS glitch, it will stop using GPS data, will just try to land straight down. The user can also easily take back FULL MANUAL control. That should always be people's first instinct. Not grabbing a towel.
). pilot of that sort of things have no right to be stressed. 
