Safety vs Law - UAV conundrums No 1413: Rising beyond 400 ft for hawks.

[AeroJ]

Now that our areas of legal flight are increasingly confined to featureless fields and whatnot, I find I am often in airspace populated by the larger hawks, whom (of course) are circling over most of the remaining attractive countryside we might be interested in, looking for small scurrying things on the ground, but also maintaining vigilant guard over their vast aerial territory, which of course has no legal upper limits

We all know that the best thing to do if a hawk is eyeing up your craft for a possible dive / strike, the very best and safest way out of that situation is the hard vertical rise above it, and then skiddaddle back home at that height, and then bring the drone down close to you or land. This is fine, and works well if I happen to be at 200 ft AGL when the situation arises. But sometimes it happens when I am at 393 ft, and of course then I have zero spare headroom to move into without breaking the law, yet, if a quick sky check reveals no aircraft in sight, the rise and flee is still the safest thing to do (IMO). We might reasonably need about 30 seconds or so of >400ft flight before we can get back down to legal maximums.

But at least for now, in the UK, my Mini 4 Pro does NOT restrict me to 393 ft AGL because our height laws mean we are OK to fly up hills and then do 393 ft above those, so I don't have that forced maximum, and can freely set mine higher, which I do, for the specific situations that demand it.

So, with all those factors in place, if you feel your craft is at risk of imminent bird attack, and you find yourself near the top of your legal range, would you temporarily exceed it by 100 ft or so to extricate yourself from the immediate danger in the best / safest way for everyone, or should absolute regard for the law take precedence whilst additionally endangering everybody - the craft, the hawk, stuff on the ground it might fall on etc etc ?

 

[Cafguy]

if you feel your craft is at risk of imminent bird attack, and you find yourself near the top of your legal range, would you temporarily exceed it by 100 ft or so to extricate yourself from the immediate danger in the best / safest way for everyone, or should absolute regard for the law take precedence whilst additionally endangering everybody - the craft, the hawk, stuff on the ground it might fall on etc etc ?

That is what I call a Pre-Flight question. You want to be on the side of safety and that side is the side that says NEVER bust the altitude rule. There are many factors to consider when flying. One of these is how do I fly and NOT violate the rules. As far as alltitude goes- They allow for Emergencies! BUT you should never put yourself in a position where it is necessary to break the rule if you have a problem. My 2 cents.

 

[akdrone]

If I were in that situation and could see my drone and there were no planes anywhere in sight and I thought my drone was in danger of being hit by an approaching hawk I would not hesitate to rise to whatever altitude was needed. The point of the regulations is safety and if that is 100% assured, moving above 400' for 5 seconds would not concern me. If an FAA official watched that I'd expect a talking to but doubt it would ever be more than that. As to "never put yourself in a position where it's necessary to break the rule", I guess one could just limit your flying to 200feet anywhere near any birds. Feel free to do that. I have never had occasion to fly near hawks that might attack my drone so it's all academic to me.

 

[Yorkshire_Pud]

Personally I regard the 400ft AGL rules as almost sacrosanct, in several thousand flights I have broken it only a few times.
One of those was in an area I know well where I have never seen a manned aircraft that was under 20,000ft+ up.
Another was an accident in the settings, I had sent the drone up a hill so had set the max height according, whilst adjusting the max height I must have touched the RTH height and set it way up there. When I brought the drone back down I sent it out over low ground. It disconnected and RTHed well above 400ft. I was bricking it the whole way down to below 400ft.
The others were forgotten experiments and I broke the ceiling only momentarily in vertical climbs to test something forgotten, I went only a few feet over 400ft and immediately brought it straight down.
Truth be told the vast majority of my flights are lower than 200ft with the max height set somewhere around there.

The point of all the above,
1) I consider it dangerous to routinely set a max height setting that is over 400ft, you should adjust it AND RTH height for each flight or if you insist on setting routine heights then set them low

RTH height can not be set higher than the max height setting.

2) If a bird of prey is interested in your drone then I doubt you will have the presence of mind or the time to go into the app's menus and adjust the max height setting so that you can breach 400ft AGL.

 

[AeroJ]

That is what I call a Pre-Flight question. You want to be on the side of safety and that side is the side that says NEVER bust the altitude rule. There are many factors to consider when flying. One of these is how do I fly and NOT violate the rules. As far as alltitude goes- They allow for Emergencies! BUT you should never put yourself in a position where it is necessary to break the rule if you have a problem. My 2 cents.

It's a good 2 cents, and thank you for it !

But I would posit that it is simply not always possible to 'not put yourself in such a situation', and nor is this entirely a pre-flight decision (for me at least). My favourite fly site for the hills of Hampshire, for example, (Stoner Hill South ridge) is in an isolated field only accessible after a 30 minute walk. On arrival I will typically watch the skies for at least 20 mins before I setup and launch to note wildlife activity, with special lookout for the large raptors. There are always some, but they are often miles away, and vastly higher than I plan to be. Obviously I won't launch if they are circling overhead or anywhere close to it, but if there are say, just 2, and they are circling a couple of km out over the valley, then I will consider it a viable thing to do to fly, with what I consider to be only slightly elevated risk... I suspect others may disagree about that.

Then I will spend some time dicking about at canopy height waiting to see if that draws their attention. 85% of the time I find it doesn't, so I consider the flight still not at major risk. At this point I may climb to 200 ft or so, and begin slow gentle filmic manoeuvres all the while noting their flight patterns to see if they are being adjusted in my direction. Again, a lot of the time, they are not and filmings continue uninterrupted, and the temptation to approach 400 ft gets (cinematically) larger !

At this point I might decide that now is a good opportunity for the one 350 ft panorama I try and get during each pack at each site. I am aware that it takes a full minute of stationary hover to complete + a little bit more for setting it up and starting regular filming again afterwards. If I am lucky the hawks will have continued their regular moves across the valley.

It is if I am not lucky here that the situation I mention can arise. If the 2 hawks do start coming over, or new ones appear that I haven't seen before, then I could find myself in the situation I describe, when at pre-flight time all looked doable...

 

[AeroJ]

The point of all the above,
1) I consider it dangerous to routinely set a max height setting that is over 400ft, you should adjust it AND RTH height for each flight or if you insist on setting routine heights then set them low

I don't do it routinely; only specifically before a flight where I know I have to fly up a hill.
BUT, and this is where we will probably disagree, ALSO if I am in an area where I know big raptors can appear.
And to clarify - I don't mean I set it to unlimited - I never set it to higher than the height of the hill +350 ft or so.
Nor do I change that in flight. I set it before launch.

If I were in that situation and could see my drone and there were no planes anywhere in sight and I thought my drone was in danger of being hit by an approaching hawk I would not hesitate to rise to whatever altitude was needed. The point of the regulations is safety and if that is 100% assured, moving above 400' for 5 seconds would not concern me. If an FAA official watched that I'd expect a talking to but doubt it would ever be more than that. As to "never put yourself in a position where it's necessary to break the rule", I guess one could just limit your flying to 200feet anywhere near any birds. Feel free to do that. I have never had occasion to fly near hawks that might attack my drone so it's all academic to me.

Yeah I think I'm kinda with you there. I would consider making that same move a thing that was fully and reasonably defensible if the CAA wanted to speak to me about it afterwards. I would hope that if those rules ARE about safety then my explanation should clear me of wrongdoing, or at worst result in a stern warning about not doing it again.
Despite the severity and seriousness of the rule I sort of have to believe their primary concern IS actually safety. Perhaps I am naïve or foolish, or just hopelessly optimistic to imagine that might be the case, but I rather cling to that hope until it is definitively dashed by something they say or do.

 

[AeroJ]

RTH height can not be set higher than tehe max height setting.

Indeed. Do we know what happens if your RTH height is the max, and your drone is above that when it gets called ? That is not something I have tested so far !

 

[Yorkshire_Pud]

Do we know what happens if your RTH height is the max, and your drone is above that when it gets called ? That is not something I have tested so far !

Barring malfunctions, your drone CAN NOT exceed the maximum height set in the app. So the proposed situation should never occur.
Of course, if the drone malfunctions all bets are off, I think the highest malfunction log I have saved reached 4,700ft.

However, if you had the drone at say 400ft with the RTH height also set at 400ft and you then reduce the max height setting to 300ft, the drone will descend to 300ft or just below it and the RTH height setting will be reduced to 300ft. I have tested that in the past.

 

[AeroJ]

Barring malfunctions, your drone CAN NOT exceed the maximum height set in the app.

Yeah yeah, but if you HAVE set it higher, for example to fly up a specific 300 ft hill with a view to doing another 300 when you get to the top, the craft WILL let you do that (or at least mine will, and it is in CE mode / no dodgy 'upgrades' straight from the factory etc etc !). So I wanna know what happens if you are at say, 500 ft (higher than your take off point, but only 200 ft above the hill the craft is physically above now) and then RTH is called, which is set to max 400 as does seem to be the case with mine too. I wanna know if it will drop to 400 ft from where it is (and possibly descend into some trees on the hill!) and THEN fly home (assuming 'preset' is set in RTH options) OR will it fly home at its current height, which will be illegal once it leaves the hill, but higher chance it won't crash ?

Also, can we adjust via stick input the RTH so that it drops as it travels back to us ? Or could we trust the 'Optimal' mode of the RTH setting to do the drop for us ?

 

[jephoto]

As far as I’m know - and others can correct me if wrong- when RTH kicks in, it will ASCEND to your preset RTH altitude- IF YOU ARE UNDER THAT ALTITUDE- but if you are at or over the RTH, it will return AT THE LEVEL ITS AT.
Then descend

 

[Yorkshire_Pud]

I wanna know if it will drop to 400 ft from where it is (and possibly descend into some trees on the hill!) and THEN fly home (assuming 'preset' is set in RTH options) OR will it fly home at its current height, which will be illegal once it leaves the hill, but higher chance it won't crash ?

If an RTH was initiated whilst the drone was above the RTH height most DJI drones will NOT descend to the set RTH height.

BUT the precise behaviour tends to be model specific, DJI have a habit of playing with RTH behaviours with/for each new model so you need to check the relevant manual.
I have a vague recollection of mention of one of the recent DJI drone that might, note might, descend to RTH height but I don't remember the precise behaviour and if that is correct then I do not remember the drone's model.
The Air 2 introduced an RTH behaviour whereby the drone would, in certain circumstances, descend during RTH whilst en route to home point but that's down a descent 'slope' and NOT vertical descent.

I would pay particular attention to any model or models that offer power saving options in their RTH behaviours.

 

[Yorkshire_Pud]

Also, can we adjust via stick input the RTH so that it drops as it travels back to us ?

My recollection is that you can BUT you need to read the relevant manual. A while back DJI changed some things with regards to RTH behaviour vs stick movements and what had previously been useful stick commands now cancel an on going RTH.

Better yet, experiment in a safe place.

 

[mavic3usa]

If you are part 107 and you do work in the city where there are several building taller than 400 feet, it only makes sense if you lose your signal due to a building blocking or interfere your drone may need to rise to 800 feet or more to prevent it from crashing into another building. Remember, the part 107 operator can fly higher than 400 feet AGL when encountering some structures in uncontrolled airspace. If you fly over a 400 feet high building with a hawk's nest on top and just as you go over the top, the hawk went to attack, the part 107 operation can legally ascend up to 800 feet to avoid the hawk for a period.

So technically by saying you shouldn't do this just because there is no building underneath you or within a quarter mile, probably doesn't make a lot of sense. Yet another reason why the law is rarely enforceable. Hopefully in the future, we can have certain areas designed at sheltered or covered operations where you can have up to 1000 feet or higher blocked off for miles in every direction because the entire area is full of high structures and mountains and it is less safe to keep drones hugging close to the ground than prohibited certain flights in the immediate vicinity to under 1000 feet. For example, the entire downtown Chicago area should have a 1500 feet dome over it where small aircraft and helicopters should fly safely but there's no reason for me to keep it down to 400 feet over Navy Pier. Maybe there are additional safety measure like enhanced LAANC or strobes or ADS-B to make this work.

 

[Yorkshire_Pud]

If you are part 107 and you do work in the city where there are several building taller than 400 feet, it

Not relevant, he is a UK flyer.

 

[AeroJ]

I suppose I could test the 'will it descend to RTH height if higher than that' at less legally borderline altitudes ! My standard RTH height for flat ground is 130 ft - would be no hassle to park at 200, then RTH and see if it drops before it gets to the landing site.

 

[Yorkshire_Pud]

I suppose I could test the 'will it descend to RTH height if higher than that' at less legally borderline altitudes ! My standard RTH height for flat ground is 130 ft - would be no hassle to park at 200, then RTH and see if it drops before it gets to the landing site.

experimentation tends to imprint the knowledge more effectively than dry reading, especially when things do not go as you expect the to

 

[Felix le Chat]

It's a good 2 cents, and thank you for it !

But I would posit that it is simply not always possible to 'not put yourself in such a situation', and nor is this entirely a pre-flight decision (for me at least). My favourite fly site for the hills of Hampshire, for example, (Stoner Hill South ridge) is in an isolated field only accessible after a 30 minute walk. On arrival I will typically watch the skies for at least 20 mins before I setup and launch to note wildlife activity, with special lookout for the large raptors. There are always some, but they are often miles away, and vastly higher than I plan to be. Obviously I won't launch if they are circling overhead or anywhere close to it, but if there are say, just 2, and they are circling a couple of km out over the valley, then I will consider it a viable thing to do to fly, with what I consider to be only slightly elevated risk... I suspect others may disagree about that.

Then I will spend some time dicking about at canopy height waiting to see if that draws their attention. 85% of the time I find it doesn't, so I consider the flight still not at major risk. At this point I may climb to 200 ft or so, and begin slow gentle filmic manoeuvres all the while noting their flight patterns to see if they are being adjusted in my direction. Again, a lot of the time, they are not and filmings continue uninterrupted, and the temptation to approach 400 ft gets (cinematically) larger !

At this point I might decide that now is a good opportunity for the one 350 ft panorama I try and get during each pack at each site. I am aware that it takes a full minute of stationary hover to complete + a little bit more for setting it up and starting regular filming again afterwards. If I am lucky the hawks will have continued their regular moves across the valley.

It is if I am not lucky here that the situation I mention can arise. If the 2 hawks do start coming over, or new ones appear that I haven't seen before, then I could find myself in the situation I describe, when at pre-flight time all looked doable...

With flights in open countryside, I've found out that the bigger birds of prey are windy buggers who'll mainly hang around at a great height and watch. The birds that will really go for it are the swifts and swallows that come in like Exocet missiles, closely followed by seagulls, ravens, magpies and the odd crow, but every time I've been 'buzzed': it's been by the little dickie birds giving it the beans a lot closer to the ground. I reckon it's because they consider the drones colour and flight characteristics (periods of static hovering) a bit too hawk-ish for their liking.
So, would I climb above the max restriction ceiling to "avoid hawk attack"? No. Would I do the same for the smaller birds? No. If one of the big hawks or buzzards really went for it: I doubt you'd have enough time to react. The smaller birds aren't attacking, they're flying to scare a 'predator' off which means they'll peel off before they hit.

Pigeons, however, are a different thing altogether. They're just Forrest Gump thick.

 

[Yorkshire_Pud]

With flights in open countryside, I've found out that the bigger birds of prey are windy buggers who'll mainly hang around at a great height and watch. The birds that will really go for it are the swifts and swallows that come in like Exocet missiles, closely followed by seagulls, ravens, magpies and the odd crow, but every time I've been 'buzzed': it's been by the little dickie birds giving it the beans a lot closer to the ground. I reckon it's because they consider the drones colour and flight characteristics (periods of static hovering) a bit too hawk-ish for their liking.
So, would I climb above the max restriction ceiling to "avoid hawk attack"? No. Would I do the same for the smaller birds? No. If one of the big hawks or buzzards really went for it: I doubt you'd have enough time to react. The smaller birds aren't attacking, they're flying to scare a 'predator' off which means they'll peel off before they hit.

Pigeons, however, are a different thing altogether. They're just Forest Gump thick.

I cant help but wonder if swifts and swallows etc. are going after insects disturbed by the drone or drawn in by the drone's down draught etc..

 

[Felix le Chat]

I cant help but wonder if swifts and swallows etc. are going after insects disturbed by the drone or drawn in by the drone's down draight etc..

Good question, but they are proper barnstormers. The way I see it is birds have been flying a lot longer than I have... they know their safety margins (pigeons being the exception again... cos they're as thick as mince). If I react by throwing the drone all over the place, it'll be my drone that causes any collision, not the other way round.

 

[chadCO]

If you are part 107 and you do work in the city where there are several building taller than 400 feet, it only makes sense if you lose your signal due to a building blocking or interfere your drone may need to rise to 800 feet or more to prevent it from crashing into another building. Remember, the part 107 operator can fly higher than 400 feet AGL when encountering some structures in uncontrolled airspace.

By the reckoning of some that isn't an excuse to break the rules, if the flight was planned there wouldn't be a structure to encounter that would empare the signal or LOS. Some live in a perfect little VR world of their own construct too.