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Comment by tjohns | Hacker News Reader

There's a photo of the damage here:

https://www.avweb.com/aviation-news/172-substantially-damage...

There's also a copy of the incident report here:

https://wwwapps.tc.gc.ca/Saf-Sec-Sur/2/cadors-screaq/rd.aspx...

More generally, I really hope the drone manufacturers invest in genfencing off controlled airspace and installing ADS-B receivers as part of a sense-and-avoid scheme to avoid potential collisions entirely. As a pilot, I'm impressed by the work DJI has been doing in this space.

(Though it's worth noting that sense-and-avoid won't solve the problem entirely, since there's a fair number of aircraft that are not transponder equipped. Canada also doesn't yet mandate ADS-B equipage.)

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The details in the avweb article are pretty damning... 500 AGL and one mile final is not even "near an airport," it's very obviously right in front of the approach end. Hard to imagine how anyone was operating a drone there without complete reckless disregard for safety.

Any reasonably professional part 107 operator (or Canuck equivalent thereof) would say hell no to operating in the glideslope of a runway like that.

In fact, Canada doesn’t distinguish between commercial and hobby RPAS operators. Anything over 250g needs at least a Basic license, and anything operating in controlled airspace needs an Advanced license and a filed SFOC. The basic license clarifies where you’re allowed to fly at all.

Soooo these clowns either had no clue at all about the licensing, or just straight up didn’t care. The IR says that Nav Canada (ATC) wasn’t informed of the flight ahead of time, so pretty unlikely that an SFOC was involved.

I can totally understand that they didn't care - they are police after all and peasant regulations rarely apply. But having no clue? I mean, if I just walk close to a runway I make sure to look in all hundred directions just in case, yet they flew right through it, yolo?

The airplane reported both 500AGL and 1NM (nautical mile) which is oddly the exact lower limit for altitude, and the exact limit to distance for 'advanced operating' drone from the airport, as far as I understand. Why those exact legal limits? What are the odds of that?

If the drone operator reported those numbers, they'd only be 100ft outside of where they should be legally.

Since both '500' and '1' are pretty arbitrary numbers, any reasonable margin of error puts a ton of range for the drone to be flying in safety while the pilot being at error. Or both.

This seems to be a 'threshold' issue, not some arbitrary invasion of space, but we'll have to wait for Transport Canada, hopefully the drone will have precise information. Correct me if I'm wrong.

This is not a threshold issue (other than a Boolean threshold of the drone operator needing to comply with the law and not doing so).

There is no lower limit for aircraft in the process of taking off or landing. I’m much more familiar with US aviation law, so I’ll give you US citation there, but it’s not likely to be wildly different elsewhere.

A fairly typical approach slope is 3°, which would put an aircraft around 320’ above touchdown zone elevation at 1 nm. There is of course some variation above and below that.

There’s no incentive for the pilot to shade or cheat their reported position. They would be legal at 419 feet and 1.625 nm just as well as 500’ and 1 nm.

Canadian regs (US are different here) require that if this were an airport without a control tower, the drone would need to be a minimum of 3 miles away from it. With an operating control tower, the drone operator needs permission and active radio contact with the tower.

The general safe altitude law in the US is 91.119*, which begins: Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes: (Necessary is consistently interpreted somewhat broadly rather than extremely narrowly.)

* https://www.law.cornell.edu/cfr/text/14/91.119

I would mostly attribute it to what the pilots are likely to notice - 500' AGL is a standard call-out on landing approach (not that light aircraft pilots necessary 'call it out' but their Foreflight or whatever very well may have), and the airport in question is actually uncontrolled so "one mile final" would be a common point to make a radio call.

So it's probably that it happened somewhere near those numbers, and they were the references the pilot readily knew of.

The last time drone training came up, I pointed out that drone operators have no skin in the game, and often act like it too.

https://news.ycombinator.com/item?id=27618757

I was admonished that I was describing the behavior of only the most psychopathic individuals. So clearly my fears were unfounded.

From the avweb article: "The police department has not commented any further on the mishap except to say the drone was part of a police operation in the area."

Perhaps someone would care to explain how the department's response is substantively different from "opsie daisy"? Is it just that the pilot happend to get lucky this time, and the mid-air collision only caused a massive dent on the engine cowling?

> I was admonished that I was describing the behavior of only the most psychopathic individuals.

A pretty apt description of the cops operating that drone...

At least in the US there are both LEO and military aircraft that fly around with their transponders turned off. I’m not sure that “sense and avoid” would’ve worked in this case if the cops decided for whatever reason they’d turn off ADS-B.

> that sense-and-avoid won't solve the problem entirely, since there's a fair number of aircraft that are not transponder equipped.

To be honest, I kinda hate the fact that DJI won't bring Airsense to the smaller drones. I love my Air 2S and I've seen it in action many times, helicopters often give you a 30-40 second window to get out of the way before you even see them.

I generally haven’t found it useful. Too many false positives, and too many aircraft not using transponders - especially helicopters in Class G airspace.

Personally I’m hoping for some basic radar functionality, but that is going to be tough in smaller drones!

I’m struggling to understand how Airsense would create a false positive (detect a plane that wasn’t there). It’s just listening for ADS-B out signals, which contain GPS position information.

Perhaps DJI could be being overly conservative in their algorithm, but the airplane that’s in the ADS-B transmission really is where it says it is.

I do a decent amount of flying in non-LAANC controlled and military controlled airspace (some near active airports). At least on the M300 RTK, their algorithms are total junk, and I get endless warnings (and serious ‘oh my god, reduce altitude now!’ type alerts for aircraft like jetliners coming in for approach - when I’m 90 degrees off their flight path, and 3-4 miles away. I also get critical warnings for aircraft flying overhead, which hey could in theory be a problem - if they weren’t climbing at 1k ft/min+, and at least 10k feet in altitude over me, when I’m at 200 ft AGL puttering around and the nearby trees are 100 ft tall.

It’s literally worse than useless, as it makes gives alarm fatigue. I’ve also had 3 sudden aircraft just showed up and almost ran me over events in Class G airspace, including one with a very expensive helicopter running nap of the earth - none of them were running transponders. But at least the helicopter pilot had some bitching sunglasses on.

> Canada also doesn't yet mandate ADS-B equipage

Neither does the US in an overwhelming majority of airspace under 10,000’MSL.

I chose to equip as I’m based at an airport in airspace that requires it, but if I were willing to move airports about 20 miles up the road, I could conceivably operate for years without ever needing to access airspace where ADS-B is required (and waivers are, anecdotally, readily granted at least for now).

“See and avoid” is the law in VMC, not “sense and avoid”. FAR 91.113.b*. (That’s US law; I suspect Canada is similar**.)

* - https://www.law.cornell.edu/cfr/text/14/91.113

** - Transport Canada, TP 14371E, Transport Canada Aeronautical Information Manual (TC AIM) (26 March 2020), RAC – Rules of the Air and Air Traffic Services, section 4.5.6. (Probably not regulatory, but likely based on a regulation.)

> Neither does the US in an overwhelming majority of airspace under 10,000’MSL.

This is a bad take. It’s required in all controlled airspace. That’s what’s important.

It’s like saying there are no traffic laws on majority of land in the US. It’s moot.

Edit: I'm wrong, read below.

It's required in class A, B, C, and E above 10,000' MSL. And within 30 nm of a Class B airport (mode C veil). That leaves a ton of controlled airspace in which it's not required. There are more class D airports and airports with class E surface areas, than there are class B and C airports.

> This is a bad take. It’s required in all controlled airspace.

That is incorrect. ADS-B out is required in class A, in and above classes B and C of controlled airspace, in the class B mode-C veils and class E controlled airspace that over both 10K MSL and 2.5K AGL.

It is not required in class D controlled airspace nor in the overwhelming majority of class E controlled airspace which isn’t covered by the prior paragraph.

* - https://www.aopa.org/go-fly/aircraft-and-ownership/ads-b/whe...

** - https://www.law.cornell.edu/cfr/text/14/91.225

I stand corrected.

> Neither does the US in an overwhelming majority of airspace under 10,000’MSL.

You are of course correct. But that's getting into the finer details of the FARs, and there's only so much comment space here. We could also talk about aircraft which don't have an electrical system. ;) I did mention that not everyone in the US was equipped, which seemed sufficient.

> “See and avoid” is the law in VMC, not “sense and avoid”.

"Sense-and-avoid" actually is the the correct term in this case. This is part of how the FAA wants to integrate commercial drones into the NAS. The idea is that future drones will have an ADS-B receiver and maneuver to avoid known traffic.

See the section on "detect and avoid" strategies here: https://www.faa.gov/uas/research_development/information_pap...

Though again, as mentioned... there are a good number of aircraft are not equipped, so this doesn't cover all possible cases.

Thanks for the links to the FAA UAS research and certification work. Sense and avoid is indeed correct in the research being done (though not yet the active federal law governing airspace).

You did mention some aircraft are not equipped with transponders, which I took to mean the common use of the term in aviation: a 4096 code mode A/C transponder, not ADS-B out.

Slightly under half of general aviation aircraft are not equipped for ADS-B out (the overwhelming majority of these do have a transponder) and at this point, it seems fair to conclude most of those will never be equipped. (If you chose not to equip for the Jan 2, 2020 requirement, all that would compel you now to take on the upfront and recurring expenses associated would be change in usage requiring regular access to 91.225 airspace. In fact, for many non-ADS-B out airplanes, 4096 code transponders now provide little value, so the first time they need non-trivial maintenance, I’d expect some portion of those to be removed instead of repaired because they’re now primarily a convenience item and don’t on their own provide access to any airspace by rule.)

I can readily imagine a future where UAS operations are allowed under 500’ AGL over cities (aircraft are already blocked from operating there except during takeoff and landing). I don’t expect a near-future where class E airspace is open to drones unable to reliably see/sense and avoid aircraft that don’t have ADS-B out. There’s just too many such aircraft and will be for decades to come unless 91.225 is substantially expanded.

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