It may seem obvious to any drone pilots with experience, that flying under large metal structures is not a good idea.  I unortunately do not belong to that category. At the end of this flight I decided to try it and my Spark dropped like a stone. Luckily above ground and only from about 4 metres height, slightly scuffing the props. Luckily it didn't try to RTH or it would have hit the underside of the bridge. Since then I have read about similar incidents and simply not flying under structures would seem to be the only sae bet.

did it actually just drop or become very hard to control? i cant see the video because im at work and my computer cant view youtube

Luckily you went under the bridge where there was land instead of the water!

Thor1 Posted at 2017-8-15 06:41
did it actually just drop or become very hard to control? i cant see the video because im at work and my computer cant view youtube

You don't actually see it at the end of the video but the motors continued to spin and it dropped straight to the ground.

Jimmers Posted at 2017-8-15 06:46
Luckily you went under the bridge where there was land instead of the water!

My thoughts exactly ;-)

McSchotte Posted at 2017-8-15 06:50
You don't actually see it at the end of the video but the motors continued to spin and it dropped straight to the ground.

i am also a new drone user and i would like some feedback from someone with some expertise if that's possible. like maybe hallmark or a dji rep! it wasn't a power cutoff and i don't see how the compass could have caused this. maybe the barometer somehow? although i don't know how metal could affect the barometer!

Thor1 Posted at 2017-8-15 07:00
i am also a new drone user and i would like some feedback from someone with some expertise if that's possible. like maybe hallmark or a dji rep! it wasn't a power cutoff and i don't see how the compass could have caused this. maybe the barometer somehow? although i don't know how metal could affect the barometer!

I'm no expert but there is all kinds of metal reinforcements in that bridge and we all know that causes interference with the compass and/or GPS.  The area that he went under the bridge had 3 sides of the Spark covered - the top, the left and the right.  With that being said it's hard to predict the behavior of the drone when any type of interference is present.

Jimmers Posted at 2017-8-15 07:09
I'm no expert but there is all kinds of metal reinforcements in that bridge and we all know that causes interference with the compass and/or GPS.  The area that he went under the bridge had 3 sides of the Spark covered - the top, the left and the right.  With that being said it's hard to predict the behavior of the drone when any type of interference is present.

thanks jimmers! so if all sides of the compass is surrounded by metal or some type of interference you think it could make the drone just drop without the motors shutting off?

Jimmers Posted at 2017-8-15 07:09
I'm no expert but there is all kinds of metal reinforcements in that bridge and we all know that causes interference with the compass and/or GPS.  The area that he went under the bridge had 3 sides of the Spark covered - the top, the left and the right.  With that being said it's hard to predict the behavior of the drone when any type of interference is present.

I see it pretty much as my own fault. In addition to all that metal and concrete, there are the power lines for the trains you can see in crossing the bridge. I think the technical description of what happened is "drone threw a wobbly" ;-)

the question I have is, why have I seen You Tube videos where a guy flew is spark under a steel bridge without it falling to the water below.  The guy talks about how to clear the bridge when flying.  He also shows him flying over large structures and showing how to calculate if your going to clear it without crashing into the structure; like a bridge.

There has to more to it than that.

Sparky_17 Posted at 2017-8-15 08:15
the question I have is, why have I seen You Tube videos where a guy flew is spark under a steel bridge without it falling to the water below.  The guy talks about how to clear the bridge when flying.  He also shows him flying over large structures and showing how to calculate if your going to clear it without crashing into the structure; like a bridge.

There has to more to it than that.

I've seen similar things!  While I wouldn't test it, perhaps if the OP had flown out farther where there was more space around the drone, it wouldn't have had any issues. Again, that's where the water is, so I wouldn't recommend it, but I've seen it done many times on YouTube.

I don't understand the correlation with flying under the bridge. The motors shouldn't shut off. The only thing i can think of is the Quad losing controller signal and then RTH is triggered. The DJI quads on default are set to rise 30m up and then RTH.

Many users i've seen, stand on the bridge and fly the quad under them. As a result, connection is lost. The Quad will wait a few seconds to re-establish connection. If this does not happen, then guess what.. the Quad will raise 30m up and RTH. If this happens under the bridge then bye bye spark.

Is that you standing in the field at the end, or are you with the people up on the bridge?  If on the bridge I could see the spark loosing the RC signal.. if in the field then the signal should have been OK.
The sparks GPS while good, is not the best I have seen.  I have had other GPSs that will maintain lock under a parking structure or even inside. The spark needs to be out in the open.  So going under the bridge most certainly lost GPS lock which puts you into ATTI mode, the spark will drift around in the wind in that mode so maybe it just dropped because of that.

LouisP Posted at 2017-8-15 17:15
Is that you standing in the field at the end, or are you with the people up on the bridge?  If on the bridge I could see the spark loosing the RC signal.. if in the field then the signal should have been OK.
The sparks GPS while good, is not the best I have seen.  I have had other GPSs that will maintain lock under a parking structure or even inside. The spark needs to be out in the open.  So going under the bridge most certainly lost GPS lock which puts you into ATTI mode, the spark will drift around in the wind in that mode so maybe it just dropped because of that.

I'd bet this is what happened.  

i have only 1 experience flying under a bridge, i didn't record it because, to be honest i forget to record 80% of the time, but i will say it was a success, it does dive headfirst into atti mode, the spark is definitely the wrong drone for bridges, i suggest staying closer to the ground than to the top, make sure your within VPS rage and like 10-15 feet off the ground or water and go slow.. if you can use tripod mode.. slow and low.. sounds counter intuitive if you want to avoid water, but if VPS can track it, then your spark will remain more stable even in atti...  as for where signal from RC will get lost, ..dont be on the bridge, that will shield it.. be at same level..

final point, spark ..at the moment is the wrong drone for these types of shots, i suggest a mavic pro or something higher end that has better VPS and 3D sensor system and can use flight autonomy better from within the app like following a line or something..

LouisP Posted at 2017-8-15 17:15
Is that you standing in the field at the end, or are you with the people up on the bridge?  If on the bridge I could see the spark loosing the RC signal.. if in the field then the signal should have been OK.
The sparks GPS while good, is not the best I have seen.  I have had other GPSs that will maintain lock under a parking structure or even inside. The spark needs to be out in the open.  So going under the bridge most certainly lost GPS lock which puts you into ATTI mode, the spark will drift around in the wind in that mode so maybe it just dropped because of that.

I was in the field with a direct line of sight to the drone.

McSchotte Posted at 2017-8-16 00:25
I was in the field with a direct line of sight to the drone.

It might have something to do with the space between the land and the bridge being so (relatively) small and thus you being relatively close to the bottom of the bridge itself.... would explain why in other videos (where they are much further below the bridge) this didn't happen.

I flew in a tunnel. That ended poorly- in fact, the Spark doesn't seem to recognize if it is upside-down, so it was sitting turtled on the ground, motors at full blast.

Why did you not include the end of the video?

tedder Posted at 2017-8-17 13:29
I flew in a tunnel. That ended poorly- in fact, the Spark doesn't seem to recognize if it is upside-down, so it was sitting turtled on the ground, motors at full blast.

Actually the Spark has a failsafe where when it flips more then 90 degrees it shuts itself off. So I'm not sure what happened to yours.

This is where I question if going WIFI has any benefit in this instance. Let me be clear, I am not a radio expert, but I've driven/flown many old RC in my day under, over and through metal structures and power lines using a plain old radio signal. You know the kind, where you had to match radio crystals in your remote and car/plane/helicopter. I decided to try the entry level Spark instead of going Mavick or Phantom/Inspire for this very reason, learning the ins and outs of these modern RCs.

A good lesson of selecting a proper flight environment. Practice makes perfect. Enjoy it and happy flying!

Thanks for the heads up

Even if it went into ATTI mode, I thought it would have kept its altitude??? why drop to the ground? that does not sound normal.

falling on the floor is kinda better than falling into the water

Thanks for sharing