Helicopter almost collides with drone

Originally published at: https://boingboing.net/2020/08/31/helicopter-almost-collides-wit.html


I’m surprised that the passage of the chopper didn’t seem to disturb the drone.


If the tower is 440’ tall and the drone is roughly even with it, it may well be right at the 400’ height limit. It may well be the case that the helicopter pilot is in the wrong here, since he nearly collided with another aircraft which appeared to be nearly stationary.


I hope you simply forgot your /s tag. A helicopter pilot travelling at helicopter speed is very unlikely to see a small drone until too late.

Maybe drones sold in the US should have an altimeter and the 400ft limit programmed in as part of their collision avoidance and airport geo-boundary software. And maybe any drone that doesn’t have such software should be banned from flying over, say, 200 or 300 feet.


Flying within 400’ of a structure sets the flight ceiling at 400’ above the peak of of the structure so the drone was flying legally. They carved out that exception to allow for visual inspections.

edit: but that looks way farther than 400’ from any building. buuuuusted


My DJI Spark (entry level) has some sort of altimeter, it stops climbing at 400’ but it does look like I can override it (never needed to).

All flights within controlled airspace must be submitted and approved through the FAA.

In an airplane the local barometric pressure must be dialed into the altimeter or the altimeter will not read correctly. I don’t do this with my drone, I’m guessing drones use a different technology to determine altitude??? Is it possible a drone can be 20ft off of actual altitude?

Both helicopters and drones can fly at 400 feet… Seems like this sort of thing is bound to happen? I’m guessing a helicopter travelling that fast might be going up and down a few feet rather than bullseyed at exactly 400? Alternatively, if the drone operator has similar software as the Spark, I don’t understand why the operator would take the steps to override the software for only 20-40 more feet???

(Just realized minimums for helicopters and planes is 500 feet)

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It might use GPS for that - and keep track of the altitude at which the flight started to get the altitude above ground level. That said, I’ve always found GPS altitude to be wonky and subject to variation.

May I ask what type of visual inspection? I mean flying a drone directly over a structure at more than 20 ft but no more than 50 ft would yield better visual inspections. How exactly would 400 ft yield better information for a structure? Using 400 ft would allow a wider range but if the rule is for an inspection, why would anyone need to be 400 feet above the structure?

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The payload carried by the chopper looks like some imaging/sensing device I’ve already seen on (or rather under) military helicopters. To me it looks they were conducting some survey above the coast line. Had the drone damaged it, the drone owner would probably be in very big trouble by now.

Yup… did some reading and DJI drones report altitude in relation to the point of launch height. So if a drone launched from a position 40 feet higher than the base of the building it would report an altitude of 400ft at the top of the 440 ft building.

Similarly, launching from a 30 ft pier would make the drone’s max altitude 430ft above sea level.

I’m probably missing something, all this seems like it is relying on the rarity of events to be “safe”.

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Video link for the BBS



The FAA works in mysterious ways! I can’t give you a exact answer to their rationale, but imagine a large tower block or arena. Getting a shot of the entire property could require you to be more than 50’ above. Take an overview shot at peak+400’ before dropping down to get specific detail shots as needed. My reference to visual inspection is more relevant to the extended height around a building. A pilot can inspect the entire height of a building, not just the bottom 400’.


Drones never have right of way.

What if the chopper pilot was not cleared to fly below 500ft but was under?

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I’m pretty sure that’s a local news chopper. The thing mounted on the front is a camera and gyro on a gimbal. We have a few here in LA like this with no local news branding on them.


Ah. I can see using a drone to get a wide view of a property, but your post I was responding to specifically said 400’ for a (my assumption) structural examination. I assumed this meant that they were trying to examine something in particular in the structure, not looking for a wide view.

I live in SoCal near enough to beaches that I’ve seen numerous helicopters fly by low over the ocean. It’s surprising that the FAA would get this wrong.

(Actually stayed at this hotel on points, right tower about second floor from the top and there were a few helicopters buzzing by so, FL pilots do the same thing.)

Assuming it’s operating under VFR rules, there is a 500’ limit over populated areas (1000’ over cities/towns), but not over water. Additionally, per Wikipedia (I don’t have the US FAR handy and I don’t feel like looking them up), ‘Other aircraft, such as helicopters, powered parachutes, and weight-shift-control aircraft, are not required to meet the FAR 91 minimums, so long as their operation is conducted without hazard to persons or property on the surface.’ Which, given it’s flying out over the ocean, I think the helicopter is meeting.


What if the chopper pilot was a wizard with a nuke? Did you think of that?

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Yeah, I see a lot of CG choppers screaming up and down the coast when I’m there. Seems like the drone pilot was taking unnecessary risks. Did they have a visual observer to warn them before the chopper got that close? Did they have good eyes on their bird at that altitude that far out?

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Then I would set the oven to broil and let the cat inside.