What May Be U.S.’s First Drone-Linked Aircraft Crash Is Being Investigated | Hacker News Reader

What May Be U.S.’s First Drone-Linked Aircraft Crash Is Being Investigated

bloomberg.com

60 pointscdcro71 comments

Summary: Flight instructor saw a drone during low-altitude hovering exercises with a student, tried to land, and hit a bush. Much like lasers I suspect the psychological role of drones as a pilot distraction could be as great or greater than the actual risk to an airframe. Article has good links to various drone collisions (all resulting in limited damage to the larger vehicle) as well as FAA study showing drones could be more dangerous to airframes than birds because of harder materials.

>Flight instructor saw a drone during low-altitude hovering exercises with a student, panicked, tried to land, and hit a bush

The pilot didn’t panic. The drone was directly in front of the helicopter.

I was making an unfair inference about the pilot's mental state, so I removed it. With that being said I still strongly question the relation of the drone to the crash physically and believe the effect of the drone on the pilot's decision-making is the interesting part of this story. Landing as an evasive maneuver doesn't make a lot of sense to me and the actual cause of the crash seems to be a situational awareness issue.

The fact is that the operation of drones is legally prohibited in certain ways to avoid any chance of drones and aircraft intercepting each other in flight.

Whoever the operator of the drone is, they are wholly responsible for illegal operation of their drone and the results thereafter.

> Whoever the operator of the drone is, they are wholly responsible for illegal operation of their drone and the results thereafter.

Absolutely correct in a general sense.

In this story though, it’s not exactly clear who is at fault though with the details given.

- Helicopter was doing hovering drills

This means they were below 400ft

- Crash occurred in a remote area per article

This implies they were not near an airport, but it’s inconclusive based on the article alone. It’s entirely possible the DJI pilot was flying on his/her own land.

- both instructor and student said they saw the drone

Doesn’t indicate how far away the drone was however. I have a feeling though either the quadcopter pilot was either flying FPV (aka in violation of the line of sight rule) or wasn’t giving appropriate clearance to the helicopter, so ultimately they could partially be at fault.

Overall, it seems to me the root cause was the instructor overreacting. The instructor should’ve landed the helicopter if they didn’t have situational awareness enough to know a tree was nearby.

Replace “drone” with any other object in the air (say a kite flown by a kid or a bird or whatever) and would you have the same “blame goes to the other party, not instructor” perspective?

I wish people wouldn't armchair-quarterback people in situations that are (likely) completely outside of their experience.

I've gone through some helicopter safety training for SAR, and been picked up and dropped off by a UH-60. The pilots spend a lot of time briefing us on all of the things they are nervous about, and there are a lot of things that they're nervous about. All of our gear has to be tight and secure. Don't have our trekking poles on our backs (common). Some of it is about passenger safety -- where and how to approach depending on the situation -- and some of it is about the safety of the craft.

When doing a hoist by air, there are a lot of things that can go wrong and many of them will be fatal for the helicopter. We have a tag line that is used to stabilize a litter as it's being lifted, because rotor wash makes the litter spin dizzyingly (and here's what that looks like: https://www.youtube.com/watch?v=msw31_dw7hE), and occasionally the tag line or something else will get loose and end up in one of the rotors and then a lot of people have a really bad day (https://www.youtube.com/watch?v=NyuQ-XG7LbY -- the pilot here is a total badass).

The areas around, under, and above the main rotor are completely unpredictable and if the drone ends up in that and gets bounced into the fragile tail rotor, it could kill the pilot and student. The pilot knows nothing about the skill or knowledge of the drone operator; putting the helicopter on the ground is safe and prudent in that situation.

>I wish people wouldn't armchair-quarterback people in situations that are (likely) completely outside of their experience.

I have flown a helicopter on numerous occasions. One does not want to be surprised by things while doing that.

Could an experienced pilot keep his cool in this situation? Of course. Is the pilot’s brain a huge factor here? Absofuckinglutely.

But yes, if you’re just doing hovering exercises, there’s absolutely no reason not to just put it down if you see something unsafe nearby — you’re usually only ~10ft above the ground anyway.

That first video looked terrifying. Is the cable also twisting and tangling while that’s happening, or is the litter spinning freely around it?

Edit: I was expecting it to stop twisting and begin turning the other way, like string that I've played with, but it just ... never did. I can't imagine the tension that would put into the cable.

Yeah, I don't enjoy roller coasters, that would not have been my favorite SAR experience.

Assuming they connected it in the usual way, it would have been twisting, but not so much tangling. It might tangle once everything was on the ground and the tension was off the line. I don't know what the hoist line material is; I'd guess a kernmantle of some kind but I'm probably wrong.

I think that's ridiculous. Pilots are correctly very reluctant to hit things. Historically, we have wanted them to do their best to avoid that.

You could argue that we should now train pilots to carefully pause and consider whether the thing they are about to hit is safe to hit. But for that, you'd have to show that the additional reaction time in avoiding collisions is really net safer. And if you did argue that, you couldn't judge the current pilots by your proposed new standard.

For those interested, by the way, in really thinking through accident retrospectives, I strongly recommend Sidney Dekker's "Field Guide to Human Error": https://www.amazon.com/Field-Guide-Understanding-Human-Error...

I read it just out of curiosity, but it turned out to be very applicable to software development.

Well by avoiding trying to hit one thing, they hit the ground. That's (arguably?) worse than hitting just about anything else other than perhaps another large aircraft or a missle.

In this case, maybe. But you have to do a sum over all cases to prove that your proposed solution is better. Otherwise it's just a way, post facto, to blame somebody. An error which is one of the biggest topics of Dekker's book.

You do realize that the ground has a fixed force based on the landing -- while an accident at 1000 ft with a non gliding helicopter means falling to terminal velocity with certain death?

To be fair, though, making evasive maneuvers to avoid a drone isn't irrational. If the drone hit the tail rotor, it could have caused the pilot to lost control.

Not long ago, a Hydro One helicopter crashed and killed four people after a tool bag came loose and hit the tail rotor [1]. It's likely that this tool bag was significantly heavier than a drone, but if you're keeping incidents like that one in mind while flying and you see a drone in your path, it's probably rational to try to evade it immediately rather than trying to decide in real-time whether the drone is massive enough to cause damage.

[1] https://www.thestar.com/news/canada/2017/12/21/unsecured-too...

The trick is that there has never been any confirmed dangerous collision with a quadcopter, all the tests have shown them less dangerous than geese, and accidents in the wild have never impacted the air-worthiness of the aircraft.

We will probably end up with the 400 feet AGL banned for aviation, and 300 feet AGL limit for recreational flying, and 100 feet of buffer.

General aviation pilots violate regulations all the time without being disciplined, and kill people once in a while, and it's a bit hard to put all the burden on the recreational remote controlled aircraft pilots.

here is a guy with a cool head on the situation: https://www.youtube.com/watch?v=K0gOxuyr438

That was a great video, thank you for the link!

I think that's a pretty sensible set of rules, but it turns gray in situations like this helicopter hover training one where civil aviation pilots have a legitimate need to be under 300ft AGL for a length of time. My intuition (and this is what I was trying to push with my comments around the collisions in the article never affecting an airframe) was that drone pilots need to be better educated around staying the hell away from other flying vehicles (which I treated as a given, probably leading to downvotes) but also that helicopter pilots will need to be trained to treat drones like geese and not to react as strongly as this pilot did, since, to your point, it's going to be hard to put the entire burden on RC pilots.

However, based on the other comments in this thread, this seems like a very controversial stance for the HN crowd, and I do sympathize with the argument from the helicopter pilot in this thread that they've already got enough on their plate without needing to handle mental interrupts from other junk flying around. The proliferation of recreational drones with terrible inexperienced pilots is definitely a problem we'll have to handle in the coming years.

there is a little issue, you don't hover an helicopter next to people and, and you don't land next to untrained people (because they could rush to the tail rotor). And they turn a lot around a site before landing, where was the pilot of the RC quad, and why didn't they see them?

Generally GA aircraft have a 500’ AGL limit to adhere to; and it’s higher above built-up / high density areas.

I get the feeling the pilots (recreational) in my area really don’t like drones. I file my flight plans electronically and, maybe this is coincidental but, every time I file a flight plan a small aircraft will apear right overhead flying low within a few minutes. It happens every time. Sometimes multiple aircraft will arrive and buzz me.

I of course have to stay under 400 feet but get this, those pilots are often flying at right around 400. I don’t know what’s going on but it’s weird. I plan to monitor the radio traffic in the area next time if I can find a way to do that.

Would love to chat more about this privately. My contact info is in my profile.

Can a drone stay in level flight in the downwash of a helicopter's main rotor? I'm not sure what their relative velocities are.

Depends on the drone and also which helicopter and how close the helicopter is to the drone (and also the ground, because of vortex ring state).

Give me criteria for the later part and I’ll be happy to calculate the likelihood.

They were flying in a remote area, low to the ground. If it wasn't by an airport and below 400 feet, I'm not sure there was any wrong-doing on the drone's part. Sometimes they're called 'accidents' aka s* happens.

That's deeply ignorant. Instead of speculating and arriving at the ridiculous idea that the only regulation is staying below 400 feet and away from airports and then anything goes, how about finding the regulation?

§107.23 Hazardous operation. No person may: (a) Operate a small unmanned aircraft system in a careless or reckless manner so as to endanger the life or property of another;

§107.37 Operation near aircraft; right-of-way rules. (a) Each small unmanned aircraft must yield the right of way to all aircraft, airborne vehicles, and launch and reentry vehicles. Yielding the right of way means that the small unmanned aircraft must give way to the aircraft or vehicle and may not pass over, under, or ahead of it unless well clear. (b) No person may operate a small unmanned aircraft so close to another aircraft as to create a collision hazard.

I mean come on. If there is an accident someone made a mistake. And if the regulations don't make clear who did what wrong, then the regulations have a mistake in them and need to be extended or clarified.

> staying below 400 feet

As someone that has spent a lot of time flying model sailplanes, I want to point out that there is no regulation which prevents a hobbyist from flying above 400ft AGL, as long as you abide by the guidelines established by the AMA or another "nationwide community-based organization".

The FAA boils everything from section 336 (the "Special Rule for Model Aircraft") as follows:

- Fly for hobby or recreation ONLY

- Register your model aircraft

- Follow community-based safety guidelines and fly within the programming of a nationwide community-based organization Fly a model aircraft under 55 lbs. unless certified by a community-based organization

- Fly within visual line-of-sight

- Never fly near other aircraft

- Notify the airport and air traffic control tower prior to flying within 5 miles of an airport

- Never fly near emergency response efforts

FAR 101.41 (b) subsumes any such guideline as a regulation. AMA's see and avoid guideline says any flight expected to go above 400 feet requires a spotter, so if you don't do that, you're violating FARs. Operating an sUAS with autopilot (among other things) has its additional advanced flight system programming guidelines, which have a hard 400 foot ceiling when operating within 5 miles of an airport. This is legally identical to having a regulation preventing operation above 400 feet AGL.

If you violate the applicable community guidelines, you're violating FARs. That's what this part says.

And then there is the catch all FAR 101.43, which is a big black hole of liability that you can also easily run into if you're unfamiliar with the national airspace system and your surroundings. If you fly a sailplane or m/sUAS above 1200' AGL in a published victor airway (this is Class E airspace), I'd argue that's a clear altitude violation of this regulations.

I disagree with your interpretation. Here is the exact verbage you are referencing from the AMA:

A spotter should be used to assist in monitoring the surrounding airspace for manned aircraft whenever a flight is expected to exceed 400 feet above the ground and that operation is expected to be in proximity to known manned aircraft traffic such as at a mixed-use facility or within three miles of an airport. The spotter must have sufficient visual acuity and be mature enough to take this responsibility very seriously.

So unless you are operating at a mixed-use facility or within three miles of an airport, you do not need a spotter to fly a model aircraft above 400ft AGL.

> If there is an accident someone made a mistake.

Yep the instructor smacked the chopper into a bush/tree/etc. The drone didn’t cause the crash, the instructor’s reaction caused it. We don’t know enough about what happened to know how far away and what actions the drone took which caused the instructor to panic (and overreact?)

I think part 107 only applies to regulated commercial operation of drones/UASs. Private operation is still unregulated.

No, in that case it's regulated under part 101.

They weren't flying in a remote area. It was a small island with a big residential development.

Maybe my reading comprehension skills fail me but here's what the article says:

"In the Charleston incident, the student was practicing low-altitude hovering in a remote area, according to the police report. As she turned the aircraft around to continue the lesson, a small white drone appeared, the instructor told police."

I've been wondering this for a long time - what's to stop a terrorist from flying and attaching a drone with an explosive payload to a large commercial flight? Especially at night while the plane is taxiing?

Nothing, apparently. I wonder though if it would be large enough to be picked up by the radar used at most airports to track planes on the ground.

All of the consumer grade drones (aka ones under $2,500) don’t show up on radar. They are too small and don’t have enough radar reflecting substances (think about a typical airframe, the motors and battery are the only really metallic parts of any size and they are still very very small compared to any aircraft).

The NSA and other intelligence services tapping the communications between the terrorists and ensuring that they're arrested before the plan starts.

The weight of the payload.

A few ounces of shaped charge at altitude would likely lead to explosive decompression.

At lower altitude, less impact, though it would still be problematic.

Keeping the charge on the target aircraft whilst it climbed to cruising height is likely the hard part.

Many consumer grade drones can’t fly high enough to get to an altitude where “explosive decompression” would be an issue. 5k ft is pretty doable, 10k ft is unlikely, 15k+ altitude is basically not tangible currently.

If the drone mates with the aircraft on ground (say, during taxiing), then all it has to do is hang on to some prespecified pressurisation point.

The fact most drones have a very small lift capacity is the biggest issue.

As to how to stop it, it’s just like any other terrorist attack. SIGINT is the main tool.

Url changed from https://www.techspot.com/news/73326-authorities-investigatin..., which points to this.

I wonder why the pilot didn’t attempt to go straight up.

Or just realise that a 1.9kg toy should be ignored rather than evaded. What happens if a goose or swan or pelican flies near a helicopter?

This feels like a "I flipped my car dodging a squirrel" situation to me, as well, although the FAA models do support the potential of 1.9kg toys to cause fairly substantial damage. I think that given all documented collisions mentioned in the article resulted in zero-to-minor damage to the larger vehicle, drones are probably best ignored as well, but to make such a sweeping generalization in something as safety-critical as aircraft will probably require years more research.

More accurately, an rc car, not a squirrel. Squirrels are part of nature, but an rc car on a highway is an act of negligence.

Here's what happens when a Blackhawk hits one with it's rotor: https://petapixel.com/2018/01/02/dji-drone-collided-us-army-...

How much do you think that cost to replace? I love my drone as much as the next guy, but someone who flies one next to a helicopter with people in it needs to go to jail.

Edit: Here's a main rotor for an R-44 for $47,000... https://m.ebay.com/itm/R44-Robinson-Helicopter-Main-Rotor-Bl...

Also a black hawks blades are probably going to be significantly stronger than those on an r44.

That's serious damage. I'm a pilot but not an engineer, I would not fly an aircraft with that kind of damage without A&P consult, and there's a decent chance only ferry flight would be legal if it were flight worthy at all.

The centrifugal force stress at the hub (root) of a blade is thousands of times the weight of the blade. Easily there's tens to hundreds of tons of force "trying" to pull the blade apart and this not so little nick, makes that much more likely to succeed.

Helicopter pilot here. We take evasive action. In forward flight that's probably going to be a quick stop to give me time to see what the bird's doing and then flying away from the bird. If I were working on hovering maneuvers and a large bird flew near I would set down until it left.

Airplane pilot here. I suspect there's enough noise and downwash/turbulence that a bird doesn't get anywhere particularly close to a hovering helicopter.

If the drone is clearly outside the radius of the main rotor, you'd set down. What if it's above the rotor coming toward you? Probably set down and hope it doesn't get sucked in? What if it's below the main rotor coming toward you? You may not want to set down unless you know (?) the downwash is something the drone can't put up with, but how much time are you going to have to decide whether to risk striking it with a rotor vs throttle up delay and ascending away from the drone?

I think the behavior of various sized drones in proximity to helicopters is going to become a necessary training item. There will be planned and unplanned close proximity of s/mUAS and the worst enemy is going to be having never thought of or discussed these operational what ifs.

Helicopters are hard. It might not have had enough time to do that (before hitting the drone)

Helicopters are slow, and they probably didn't have the rotor speed needed to yank the collective.

Hitting a 2kg drone would result in expensive repairs, e.g. $30K for replacement rotor blades and you still might crash.

I probably would have taken the hit but I'm much better off than the average R22 pilot who often operate or razor thin margins.

That said; my bet is that there was no drone. My guess is the student made a small mistake, the teacher took over and made a bigger mistake, and both want to keep their jobs/future carers. Drones make an easy target to lie about and are hated anyway. Not to say there are no irresponsible drone pilots, just currently I think it's more likely heli-pilot error at this stage. My hope is the GPS tracking in the phantom well let us know for sure.

Was it 2kg or 0.5kg drone? Is there much difference between two, afaik all of them are more or less plastic.

If planes and helicopter are ok with hitting birbs, perhaps we should regulate drone manufacturing to be more like birbs: https://www.youtube.com/watch?v=jl-27Bk_RME

Drones have harder parts and I would expect hardness to play a big role in damage done. But it doesn't even need to be hard, raindrops can also do a fair amount of expensive damage.

I'm curios on the 10+ downvotes this received since posting; would someone care to give me a reason. Thx

I did not down vote. My guess is the mudslinging:

My guess is the student made a small mistake, the teacher took over and made a bigger mistake, and both want to keep their jobs/future carers. Drones make an easy target to lie about and are hated anyway.

Ah, I consider them human with human faults and incentives. One really sad aspect is that a major killer of helicopter pilots is cutting corners on preventative maintenance in order to save money. I feel like we need to be honest on what people are like.

When making such points, it usually helps to talk about the systemic or situational factors pressuring people to do such things and to frame it as one plausible explanation that fits the scenario as presented rather than as an accusation.

You need to be very careful about making public accusations (or sounding like you are). That can seriously harm people's careers and lives.

I suspect that filing a false report with the NTSB would be a crime, in which case you'd be accusing the crew of breaking the law, perhaps even perjury.

I hope one day drones are regulated similarly to guns, i.e. de facto banned unless some exception applies, such as:

- you're in the middle of nowhere

- you're doing it exclusively on a property you own (and the property is large enough)

- the use case is in the public good (e.g.: police can use guns)

In other cases, the downsides are large given potential for abuse/voyeurism/sabotage, and upsides seem nil.

> I hope one day drones are regulated similarly to guns

What country are you in?

USA, which, contrary to popular belief, has lots of restrictions on the use (though not necessarily ownership) of guns. Try discharging a weapon anywhere near a major metropolitan area and let me know how it goes :)

> Try discharging a weapon anywhere near a major metropolitan area

I used to do it all the time in a major city. Shooting ranges exist inside major metropolitan areas you know.. ;)

Yes, I know that isn’t what you meant, but broad waving statements deserve this kind of response imho.

Yes, and those could fall under the properties you own exception (or have permission to use from the owner).

Again, wrong. If I own a property in a major metropolitan area, I generally can’t discharge a firearm in the city just because I do it on my own property.

This is why I said, in my original comment, "and the property is large enough" (implying it doesn't interfere with others; or you have a permit, ...).

I'm sure you knew that though. What exactly is your point? Would you like me to rewrite my original post in fully specified legalese just so you can't nitpick? :P

Where did you say “the property is large enough”?

https://news.ycombinator.com/item?id=16404025

Done here.

That seems very excessive, though regulation so far has been positive. Not that this is you, but fear of "voyeurism" is often said by people who aren't familiar with drones. I've owned multiple drones and would never consider them a spying tool since they aren't discrete/sound like a flying lawnmower. Additionally, most drones are equipped with wide-angle lenses which means you'd have to get pretty close to spy.

My main worry about drones comes from terrorists using them where crowds of people are gathered (concerts, events, etc), as other people have mentioned.

It doesn’t really matter how discrete or not they are if even if you know about it you can’t do much about it.

I’m also not convinced by a “don’t worry the camera is bad” argument; looking at drone footage online it seems to have plenty of resolution to distinguish people in one’s backyard, for example, and I’d expect those to only get better over time.

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