Flying under bridges

lertsek · Dec 14, 2018

Dropbox - Gold Hill.MOV
I edited the first few seconds just to put the fish splash at the beginning, but actually started from beyond the railroad bridge. I was a bit leery of all the metal and the glassy water, but had no problems.

ciscokid · Dec 14, 2018

very nice.

m0j0 · Dec 14, 2018

Very cool

jherridge1 · Dec 15, 2018

Hi Mojo, this is a good question. From my first-hand flying experiences, I believe there are five key factors you should consider or be aware of before flying in this situation.

1) Flying VLOS is obviously preferred for maintaining transmission connectivity.

2) Tranmission system: using an Occusync based system (Mavic Pro) performs better than a WIFI based system (Spark) for signal reliability.

3) Flight mode: be prepared to fly in ATTI mode if GPS mode is lost.

4) Bridge material: concrete structures with steel rebar tend to be more problematic than just steel bridges for me (compass calibration errors when setting up near bridge, potential video signal loss while in flight).

5) Wind conditions may play a factor depending on the shape of the bridge and land where you might experience a Venturi effect where the wind flows faster than expected, but not very common.

Clockman · Dec 15, 2018

m0j0 said:
Guys -

I'm curious. How many of you routinely fly under bridges? Do you have issues doing that? I would expect there would be GPS loss. Any other issues flying under or through structures outside. I you have videos please share them. Thank You

Flying under, over and through.

flying thru the bridge was a little dicey though.

Gavinwr27 · Dec 15, 2018

swooshdave said:
This was me flying under a couple wooden bridges. Pucker factor was high as I obviously lost sight momentarily. I guess I should get reported to the FAA for no VLOS.

You’ve got some nice footage there. Nice Guzzi as well.

Dingo · Dec 15, 2018

m0j0 said:
Guys -

I'm curious. How many of you routinely fly under bridges? Do you have issues doing that? I would expect there would be GPS loss. Any other issues flying under or through structures outside. I you have videos please share them. Thank You

this is what can happen( from youtube). personally I have flown under a large concrete bridge ok but then flying under a steel bridge/awning the mavic drifted sideways then to my surprise dropped height as well.I think the steel caused compass intererance

m0j0 · Dec 16, 2018

Clockman said:
Flying under, over and through.

flying thru the bridge was a little dicey though.

It bounced a little going through the Bridge. Was very cool though thanks.

m0j0 · Dec 16, 2018

Dingo said:
this is what can happen( from youtube). personally I have flown under a large concrete bridge ok but then flying under a steel bridge/awning the mavic drifted sideways then to my surprise dropped height as well.I think the steel caused compass intererance

Nice... that really sucked.

John Suhr · Dec 16, 2018

swooshdave said:
This was me flying under a couple wooden bridges. Pucker factor was high as I obviously lost sight momentarily. I guess I should get reported to the FAA for no VLOS.

I think I would have just walked it through

Wr4ptr · Dec 16, 2018

swooshdave said:
This was me flying under a couple wooden bridges. Pucker factor was high as I obviously lost sight momentarily. I guess I should get reported to the FAA for no VLOS.

Really nice video. Beautiful area and you got some very nice shots in there. Looked like a fun day. Thanks for sharing! (Did I miss the goose?. . .Oh, wait, I get it, it's the motorcycle. Yeah, that's nice, too).

packnrat · Dec 16, 2018

I would think a deep gourge that is narrow would be more of a problem. lost of line of sight to the gps. But if your controler disconcts a rth should save the day.

swooshdave · Dec 16, 2018

John Suhr said:
I think I would have just walked it through

Well, there's no fun in that.

DrRobin · Dec 17, 2018

Loss of GPS is unlikely except for a very wide bridge. If you are getting enough sats then there will always be 4 visible and anyway there is a time out on the GPS signal, so the position stays current for at least a second. Even if you loose GPS, your drone doesn't fall out of the sky.

You might loose the video or control signal and a RTH could be a disaster, it could just slam straight into the bridge as it ascends to the safe height.

But wait, isn't a bridge a structure and you have to keep 50m (150ft) away from structures you don't own so aren't you in slightly dodgy territory anyway. Plus if the bridge is still in use you might not be popular with the bridge owners. If a drone ran in to a rail bridge for example, Network Rail (UK), would probably have to send someone out to inspect the bridge, before they deem it safe to run trains over.

Aircraft (except sea planes) are not allowed to fly under bridges, so I expect the CAA/FAA will take a dim view of a drone flying under a bridge. Pity, because it makes for a spectacular shot.

swooshdave · Dec 17, 2018

DrRobin said:
But wait, isn't a bridge a structure and you have to keep 50m (150ft) away from structures you don't own so aren't you in slightly dodgy territory anyway. Plus if the bridge is still in use you might not be popular with the bridge owners. If a drone ran in to a rail bridge for example, Network Rail (UK), would probably have to send someone out to inspect the bridge, before they deem it safe to run trains over.

Is that 50m rule for US or UK or both?

m0j0 · Dec 22, 2018

Recreational fliers in the U.S.

Fly only for fun or recreation
Follow the safety guidelines of a model aircraft community-based organization
Fly at or below 400 feet when in uncontrolled airspace (Class G)
Fly within visual line-of-sight, meaning you as the drone operator use your own eyes and needed contacts or glasses (without binoculars), to ensure you can see your drone at all times.
Never fly near other aircraft.
Never fly over groups of people, public events, or stadiums full of people.
Never fly near or over emergency response efforts.