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

    @John, I have to disagree here.  While I support the encouragement of safe and prudent practices, we shouldn't accept an untrue safety story.

    I'm very unhappy that anyone wishing to spread FUD about unsafe drone piloting will be able to use DIY Drones as an authority on this.

  • Developer

    The validity of this one story is not what is important here. Even if this event turns out to be totally bogus, we all know that somewhere in the world, a similar event or worse has already happened and will happen again.

    My view on this is the same as always. As long as we keep lowering the user threshold and turning copters into something mainstream, more and more unwanted events will happen. That's just how it works.

    In the early days of cars, anyone with money could get one and run amok on the streets without any training or traffic laws to obey. Needless to say, that changed over time. The same will happen with this type of technology. The is to much economical pressure and possible safety issues for it to not happen.

    But at the moment the best we as a community can do, is to try and inform new users.

    Uninformed people will do "stupid" things. It's not necessarily a matter of intelligence, but a lack of knowledge to make informed decisions. Most people are sensible and just need a little bit of experience and understanding of the risks involved. This is where we should focus our energy.

    And then there are the few ones that are plain dumb asses who will do anything for a kick regardless of regulations, laws or safety hazards to themselves or even worse others. And sadly there is not much that can be done to prevent such cases.

  • I agree with Euan.  Seeing a multirotor 500' below you, against complex geography, with intermittent visibility, and to be able to claim that it is rising is a pretty dubious claim.

    Mark Harrison, agreed.

  • Moderator

    All the hallmarks of an urban legend.

    After going and reading the article, it's literally of the "friend of a friend" variety.  Let's see some facts before we get too knicker-twisted over all this.

  • @Justin: I'm not promoting a "what's the big deal" attitude, but do question the statement that any collision would have resulted in loss of life. I utilize 6 safety rules on my operations, one of which is altitude, the most important being not to fly over people.

    Building in artifical altitude limitations is a bad idea, it leads to a bunch of engineers assuming responsibility for what another person is doing. It's a much better proposal to leave all responsibilities with the operator, like this guy and increase awareness about safety. One such thing could be recyclable paper folders when an Iris or quad gets sold that have "don't do..." messages on them. I consider them more effective than artificial limitations in code.

    Where limitations in code are useful is if there are situations that could theoretically occur that are not the intention of the operator. For example the geofence.

    We probably know the urban myth of the old lady, the poodle and the microwave to dry the dog in, which is comparable in similar ways to ignorance in operation. I don't see microwaves being sold with pet detectors in them to prevent issues like that happening again. Instead, they issue a disclaimer and a manual that is supposed to be read that dictates proper use and raises awareness.

    Another bad thing about introducing these limits, assuming responsibility, is that it creates confusion in potential court cases. If a vehicle was "designed" to fly safely and look after these rules, but at some point it didn't or it was circumvented, how are they going to treat the case?

    Now imagine your surprise when you're flying in Switzerland, Peru or any mountainous area and you're trying to climb over 400ft to avoid a mountain... Unless all DTM's worldwide are integrated onboard (this flight happened FPV?), you're not going to make this effective if you assume the world is flat.

    Besides... should I not be able to execute an autopiloted flight at 1000' in the Amazon, Sahara, Australian outback, arctic, inlands of Brazil, inland China, above the sea, etc?

    There's an interesting couple of events happening in France and Holland. The one in France raises penalties for people engaging in so-called dangerous operations (flying near eifel and in cities). In Holland a teenager got apprehended by police, but their reaction was shock at how little the guy was aware of regulations, which led them to believe the right way forward is raising awareness. Some people do not visit forums like this prior to purchasing equipment, they get them online and go fly.

  • Lets hope the education happened before the fines?

  • Moderator
    Big fines will help with education, just look at France. One year in jail or a 75K Euro fine now.
  • Gonna stick my oar in here...


    I disagree that we should be hardcoding to 400ft - this is a very US-centric view, and does not apply to all countries. You are forcing less restrictive countries to abide by US rules, and this has proven to be not popular. (See: FATCA). It will only damage 3DR sales abroad.


    55mph speed limits don't mean your 200mph Ferrari has a speed limiter coded in. If you applied this to automobiles (which kill far more poeple that anything else), there would be outrage. Instead, people are trained to adhere to these limits, and are penalised when caught infringing them.


    They also tried limiting motorbikes in france to 100hp, and look what happened - unrestricted imports increased massively, french bike dealers took it in the ass. Number of motorbike deaths were unchanged. Only when they introduced improved testing and training, did deaths come down (very slightly).


    Time and time again, this intervention policy has been proven not to work. Education, Education, Education. And enforcement. That's the key. Enforcement can only be effective, if the FAA would get it's head out its ass. Education will only become effective once the rules are clear - again, FAA.


    Second, something about this story doesn't make sense - a MR sharing a thermal? The guy was able to spot a small MR 500ft below him against a complex background, with intermittent visibilty, and he was able to tell it was rising?

  • MR60

    I feel compelled to react on the focus this discussion has taken about altitude being THE issue for this community. I do not believe altitude self-censorship with code and hard coded parameters restrictions would be any solution. I believe most of this community energy should be focused on improving reliability of APM software in all possible steps to improve safety and perfectly controlled behavior of the autopilot. This would be the best bet FAA would allow uses of APM based UAVs : make APM impossible to fly away, build redundant critical functions based on voting systems, integrate parachute functionality, etc,etc

  • Wow!  Why all the self-flagellation?  He was up there having fun with his quad, bending guidlines into bananas but not actually breaking any rules.  The glider pilot was also up there for fun too.  He was VFR and had his own responsibility to SEE and AVOID, which he successfully did.  If anything, it reinforces the need for a good lookout for all concerned, glider pilots as well.

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