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Flying under bridges...eek!

Thwyllo

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So, for Air users specifically; before I try it, only to watch my pride and joy fall into a river, what has been people's real-life experience of flying under bridges in terms of potential or actual signal loss?

How close did you get to the bridge to control the drone, did you lose signal, even if just momentarily, and what sort of bridge was it? Large, small, metal, stone etc..?

Thanks!
 

Mike_Flys

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So, for Air users specifically; before I try it, only to watch my pride and joy fall into a river, what has been people's real-life experience of flying under bridges in terms of potential or actual signal loss?

How close did you get to the bridge to control the drone, did you lose signal, even if just momentarily, and what sort of bridge was it? Large, small, metal, stone etc..?

Thanks!

I had a friend loose a mavic Pro that way.
I have flown with floats when flying over water ever since.
27750258_10215393345371993_9177578821875296889_n.jpg
 

Thwyllo

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It's not the water that bothers me it's the signal loss, and for clarification I'm not talking about going under an 8-lane highway bridge with a railway underneath, just smaller wood or stone bridges say 10-15 feet wide.

How did your friend lose his - was it a big bridge and did he have an irretrievable loss of signal?
 
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ScottC63

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So, for Air users specifically; before I try it, only to watch my pride and joy fall into a river, what has been people's real-life experience of flying under bridges in terms of potential or actual signal loss?

How close did you get to the bridge to control the drone, did you lose signal, even if just momentarily, and what sort of bridge was it? Large, small, metal, stone etc..?

Thanks!
Hi Thwyllo,
I'm new to the world of drones and just joined the Mavic Pilots group yesterday. So take my comments with that in mind. I'm just learning my way around here and noticed your post as one of the most recent and wanted to say hello and and share my two cents. As is the case with any good pilot, you are doing the right thing by pre-planning your flight into a situation that you have not experienced previously.
A couple things I would consider and / or keep in mind before giving this a try would include:
  • How far away from you (and the controller) would your "Air" be from you when it went under the bridge?
    • Obviously the closer you are to the drone, the less likely it is that you will lose signal.
    • Consider your position with the controller during the adventure. Try to position yourself so that the the time the drone would not be in direct line-of-site of the controller would be minimized and of course have a Visual Observer positioned so they are in a position to monitor the bird anytime it would be out of your line-of-site.
  • What are the surroundings like?
    • For example, is this in a heavily wooded area or would there be clear sky and limited (or no) obstructions around the bridge?
    • This would be important in weighing the risks. If you did lose signal and there was little or no obstructions along with clear sky above in the area, the risk involved with an automated Return to Home would be reduced some-what. Of course a RTH being initialized while still under the bridge or with other overhead obstacles nearby could potentially prove disastrous.
  • Now I am definitely just thinking out loud here as I am not very familiar with the Intelligent Flight Modes on my Mavic Pro never-mind on the Air. Is there a I.F.M. that may allow you to preset your course under the bridge? It *may* give the drone a little more incentive to follow through and continue out from under the bridge into clear sky if it does lose connection to the controller. At least long enough so that if an automatically initialized RTH were to happen, it would be more likely that it would be clear of the bridge. Again...just thinking out loud as a new guy. I imagine there are far more experienced pilots that can weigh in with hands on experience with this sort of thing.
Good luck and fly safe!
- Scott
 
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Thwyllo

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@ScottC63 some useful feedback, thanks.

Pilot in shot, always a PITA I guess. My initial thought was off to the side on the bridge approaches or on the bank, but the wide angle perspective will always have me sight. So I either try to look nonchalant (!) or accept the issue and go with it..that means maybe sitting on the middle of the bridge with my body between me and the drone (so the controller can't be seen) for a short period then, as soon as it's gone under the bridge, diving across to the far side to resume "business as usual".

If anyone has crashed doing that I just need to know, otherwise it's going into my schedule :)
 

GavieboyDji

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I'm sure the drone doesn't just lose connection when you fly under bridges it just drops into none GPS mode and if it is dark then into attitudes mode I've done it loads with my spark and mavic pro.
 

Mike_Flys

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It's not the water that bothers me it's the signal loss, and for clarification I'm not talking about going under an 8-lane highway bridge with a railway underneath, just smaller wood or stone bridges say 10-15 feet wide.

How did your friend lose his - was it a big bridge and did he have an irretrievable loss of signal?

And that’s why the floats.
My buddies first Mavic Pro is at the bottom of the Saint Johns River. He flew it under the bridge and it took off on its own out of his control and it crashed into the water.

I have never experienced controller signal loss on my Mavic Pro or my Mavic Air.
I have lost video signal, and actually quite frequently with the Air to the point I don’t trust.
And I have flown my Mavic Pro into a tree branch causing it to fall into the Dora Canal... if it didn’t have its floats I wouldn’t be flying it today.

Signal loss especially on. The Air is a real concern around structures. If your over water what it may do if you loose signal should be a concern as well.

Biggest downside to floats on the AIr is it really kills the flight time. A getterback if you can find one maybe a better choice.

Also if you have insurance of any type find out if you have to produce a broke Drone to file a clam.
 

Mike_Flys

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I have been flying RC helicopters nearly 20 years. And DJI drones since the Phantom 1. I have owned dozens.
I have modified them and even built my own from scratch. Point is I have a bit of experience.

The radios have come a long long way, however anytime you put a structure in between the radio and the Drone you increase your risk for some sort of interference.

Ideally DJI copters RTH if they loose connection, but I have had them take off and fly in a direction I didn’t send them and have had them just sit there and not respond to the remote input.

Ideally if you stay line of sight you should be fine.

Mike
 
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ac0j

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I have seen a few videos of crashes while going under bridges.
I think the common thing that happens is first you lose connection to the drone because it is blocked by the bridge. Compass and GPS errors insue. When the mavic cant see the remote anymore, it hovers for a bit, then RTH is initiated. If you are under a bridge when this happens the mavic attempts to climb to the RTH altitude and crashes into the bridge. The uneducated Mavic owner will say "it was out of control flying on its own"

For the following months you will have to argue with DJI about not replacing your drone for free.

I wouldnt risk it unless your OK with the potential loss of your investment.
 
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Thwyllo

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Point taken, although as I said earlier, I'm only taking about a ten foot wide bridge, not a massive road bridge. I might try it on a dried up riverbed first and see how it goes.
 
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dwallersv

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Biggest issues are problems with VPS (doesn't do well over water), and metal in the bridge messing up the compass.

It can be done safely. Turn off VPS. Transient compass errors will be ignored by the aircraft if its moving fast enough and can determine course from GPS, with the compass sensor loss being brief. So don't go under the bridge, stop, and linger.

Of course, if it's a wooden bridge, probably not any compass issues. I've shot some awesome footage under an old wood covered bridge, spending 10 minutes or so under there. VPS off of course.
 
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Thwyllo

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And @Milkman670 wins the internet today ;)

How far away from that bridge were you - I'm guessing a distance because of course then your signal could more easily follow the drone through it, but as I was about to say to @dwallersv I'm only aiming for a transit flight,a bit slower than yours but no more than 2-3 seconds underneath. So that's it, key seems to be LOS through the bridge and up out of any trouble straight after (edited out of course!).
 
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Milkman670

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And @Milkman670 wins the internet today ;)

How far away from that bridge were you - I'm guessing a distance because of course then your signal could more easily follow the drone through it, but as I was about to say to @dwallersv I'm only aiming for a transit flight,a bit slower than yours but no more than 2-3 seconds underneath. So that's it, key seems to be LOS through the bridge and up out of any trouble straight after (edited out of course!).
Bridge was about 2km and I did have some connection glitches, that's why the stop just before to line up for strait shot under. A train going over would have been interesting.
 
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Rjfisher

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So, for Air users specifically; before I try it, only to watch my pride and joy fall into a river, what has been people's real-life experience of flying under bridges in terms of potential or actual signal loss?

How close did you get to the bridge to control the drone, did you lose signal, even if just momentarily, and what sort of bridge was it? Large, small, metal, stone etc..?

Thanks!
I haven't had an issue. Just flew under one back in April without issue.
Ryan Fisher on Instagram: “#tbt to my birthday weekend where I got to spend some quality time with @kayla.fisherb and relax in Leavenworth for a bit. #pnw #birthday…”
 
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cHaNcHeN

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I have been flying RC helicopters nearly 20 years. And DJI drones since the Phantom 1. I have owned dozens.
I have modified them and even built my own from scratch. Point is I have a bit of experience.

The radios have come a long long way, however anytime you put a structure in between the radio and the Drone you increase your risk for some sort of interference.

Ideally DJI copters RTH if they loose connection, but I have had them take off and fly in a direction I didn’t send them and have had them just sit there and not respond to the remote input.

Ideally if you stay line of sight you should be fine.

Mike
What if you switch the RTH to Hover just before you pass under the bridge so if you lose the signal instead of the drone climbing up in a certain altitude it will just stop & hover until you get closer to the aircraft & retrieve back the signal. Some shots just way look better under the bridge.
 

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