3D Robotics

Glider pilot surprised by drone in thermal

3689577497?profile=originalA disquieting report from our friends in the manned soaring world. Yet another reminder to STAY BELOW 400 FEET!


From Soaring Cafe:

One of the pilots in our local soaring club was surprised to discover that he was sharing a thermal with a model aircraft [commonly referred to nowadays as 'Unmanned Aerial Vehicles' (UAVs)] at ~2,500′ MSL (~1,800′ AGL). With the proliferation of such aircraft, glider pilots may need to be especially vigilant for unmanned aircraft. As one of our club instructors informed us, in the United States, UAVs are required by the FAA to remain below 400′ AGL or have a Certificate of Authorization (CoA) to operate at higher altitudes (but see the link in the quote below for clarification on the FAA’s stance regarding UAV operating altitudes). CoAs are currently only issued for restricted areas in the Continental U.S.mIn any case, we need to be on the lookout for unmanned aerial companions while soaring.

Here’s the pilot report:

Today I had what looked like a fast quadcopter join me in a thermal above Cecil Ashburn Drive.

I think I was at about 3,100 feet MSL. The copter was about 500 feet below and gaining.
At first I though it was a bird, then a mylar balloon, then a manuevering craft with a red blinking light.
He was turning the same direction I was, but turning at a different rate so I couldn’t continuously see him.
I bugged out.

The thing that bugs me is that if there was a midair, he’d be out a copter, I’d just be out.

Anybody know what the rules are in this situation?
Prior arrangement for formation flying.
Glider versus powered right of way.
Anything goes if you can get away with it.

Here’s a link to the quadcopter community’s thoughts on the rules.


The quadcopter folks agree that AC-9157 does specify a limit of 400 feet and line of sight, But they say that the process that makes an AC is not a rule- making process with a public comment period and so is not binding on the general public. They claim that the FAA has admitted that this is correct in court. They say this leaves 14 CFR part 91. Does a particular section come to mind in there that might apply?

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  • Moderator
    Plus, there are many of us you are not within the FAA jurisdiction, so hardcoding similar limits within the software would seem unnecessary, and even intrusive.
  • Wow. Major props to that guy for keeping his cool. 

  • @justin: You mean like one of these bird strikes from my alert subscriptions of near traffic accidents, this one from yesterday?: https://www.youtube.com/watch?v=cm5PaXDBPT4My biggest issue in the story is the over-generalizing statement: "if there was a midair", which I interpret as "if there was any midair". If the quad touches any part of the hull I suspect it's game over for the quad, not much damage to the glider. The biggest threat would be a windshield collision and this depends how fast the glider flies in relation to the quad.

    50% of bird strikes are related to predatory birds, which have no fear. I suppose that anyone flying FPV head-on with any aircraft isn't going to try to play chicken, so we need to consider the possibilities of hitting multirotors from the side or the back, out of view of the main camera and the consequences of such a collision.

    I'm not disputing the 400' rule here, which I promote myself, but I notice from the comments a kind of consensus that borders on collective reprehension, rather than an objective consideration of the events and a rational evaluation of the (actual) risks. It's a bit like knee-jerk legislation that requires people to blow into alcohol detection tubes in cars prior to allowing them to drive, but then for everyone even for people who don't even drink.

  • Hi Rob, I agree that the firmware should come with a "parameter" preset to 400' AGL or more correctl above launch level.

    But it should be parameter, because there are adequate instances (hills and mountains) where 400 AGL might be reasonable but 400 above launch level would not and besides, our firmware shouldn't actually make rules, just give them the opportunity and point them in the right direction.

    If we get into the business of trying to limit what they can and can't do it will open a really unpleasant can of worms.

    @ Brent, it is not at all clear that Trappy is an offender yet let alone "one of the worst ones".

    I truly wish him the absolute best in his "test" case.

    And interestingly enough most of the long distance attempts I have heard of are actually being done within the law (Line of sight and below 400 feet) - generally a really, really boring endeavor, they should get a badge for staying awake.

  • @Mark, they don't sell F3 Soaring planes for $299 at the local hobby shop where you charge the batteries and go fly it at that altitude with no previous experience.

    @Bill, yeah, I'm aware Skookum did it for liability reduction, and 3DR boards don't come with firmware. But isn't that just kind of a cynical view on the whole thing?  "We've covered our own butts, so why do any more than that?"  Isn't anybody compelled to do better?  At least Skookum's restriction can't be removed, so they've done a solid job.

    I'm completely aware that we can't stop people who want to remove the limit. And I'm not really suggesting we try.  I wouldn't want the limit to be permanent, even if we could. Heck, I don't want the limit for myself, because I might have need to exceed it in some instances (I don't know what yet, but I concede the point that it shouldn't be absolute).  But we can at least put in place a minimum level of effort to do so.  Is it too much to say that, if you can't compile the code yourself, or at the very least find a parameter in the advanced parameters list and change it yourself, that you're not qualified to exceed 400 feet?

  • Moderator

    @Gerard, they get sucked into the engine!  oh wait...

  • @Gerard... You apparently haven't seen the damage that a bird can cause.
  • @Bill Bonney:

    Thanks, I never thought of that. 

  • Is it true though that a glider can be taken out by a quad?  I seriously doubt that. 

  • How about the 100KM badge? are those guys noobs also?

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