I got *VERY* lucky!

[Greg-614]

Took my first run under a bridge tonight and slipped up and ascended too quickly at the far end. WHOOPS! Thankfully it still flew and even though I could have easily recovered had it gone real bad, I'm very very fortunate the the only 'damage' was scuffed up blades, which I immediately came back, landed and swapped them out.

WHEW! Lesson learned, perform a better recon and pay close attention to where you are!!! ?

 

[lannes]

Flying under a bridge may cause magnetic and gps interference as well from the rebar or metal structure

 

[Greg-614]

Flying under a bridge may cause magnetic and gps interference as well from the rebar or metal structure

Yep. I ran it a second time and without my fat fingers, it worked fine.

 

[HoosierFlyer]

Flying under a bridge may cause magnetic and gps interference as well from the rebar or metal structure

Would like to see proof of it happening. Ken Heron on YouTube flies under bridges allllll the time without any issues.

 

[Greg-614]

Would like to see proof of it happening. Ken Heron on YouTube flies under bridges allllll the time without any issues.

I can see how it could, don't know that it's a matter of fact thing though based on my experience tonight. This was MY fault, I never lost connection or had any GPS errors, etc. Now, this was a short bridge so it may not have had enough time to get into trouble electronically.

 

[GadgetGuy]

I can see how it could, don't know that it's a matter of fact thing though based on my experience tonight. This was MY fault, I never lost connection or had any GPS errors, etc. Now, this was a short bridge so it may not have had enough time to get into trouble electronically.

Depends upon the speed at which you fly under the bridge. MA2 max in N mode is 27mph or 40 feet per second. Any GPS or signal issues require some 3 seconds of loss to trigger any change in flight. So, if traveling in max speed in N mode, you can travel 120 feet before RTH would be triggered. If the bridge width is shorter than that, it shouldn't be a problem. If you need a wider width, fly in S mode to almost double that width! The faster you fly, the safer, as long as you don't ascend too soon! The delay in FPV will mess with you, along with the limited field of view. Stay low, until well past the far side of the bridge! If you can see the underside of the bridge from the front as you go under, you shouldn't strike the bottom surface of the bridge. Try low tide instead of high tide for more clearance under salt water foot bridges!

 

[Greg-614]

Depends upon the speed at which you fly under the bridge. MA2 max in N mode is 27mph or 40 feet per second. Any GPS or signal issues require some 3 seconds of loss to trigger any change in flight. So, if traveling in max speed in N mode, you can travel 120 feet before RTH would be triggered. If the bridge width is shorter than that, it shouldn't be a problem. If you need a wider width, fly in S mode to almost double that width! The faster you fly, the safer, as long as you don't ascend too soon! The delay in FPV will mess with you, along with the limited field of view. Stay low, until well past the far side of the bridge! If you can see the underside of the bridge from the front as you go under, you shouldn't strike the bottom surface of the bridge. Try low tide instead of high tide for more clearance under salt water foot bridges!

Great info! Thanks!

 

[bp328i]

Depends upon the speed at which you fly under the bridge. MA2 max in N mode is 27mph or 40 feet per second. Any GPS or signal issues require some 3 seconds of loss to trigger any change in flight. So, if traveling in max speed in N mode, you can travel 120 feet before RTH would be triggered. If the bridge width is shorter than that, it shouldn't be a problem. If you need a wider width, fly in S mode to almost double that width! The faster you fly, the safer, as long as you don't ascend too soon! The delay in FPV will mess with you, along with the limited field of view. Stay low, until well past the far side of the bridge! If you can see the underside of the bridge from the front as you go under, you shouldn't strike the bottom surface of the bridge. Try low tide instead of high tide for more clearance under salt water foot bridges!

RTH wouldn't be triggered by a loss of GPS, it would just go into ATTI mode.

If you lose connection between the MA2 and the controller then you have a whole different set of issues to worry about if you're under a bridge at the time.

 

[Greg-614]

Looking for some advice. As I said, the only visible damage are some scrapes on the rotors. I believe contact was extremely brief. A visual inspection fire not reveal anything. Should I have the motors tested to make sure the sudden drag did not happen them? Could an experienced person tell from the logs if they bound up are all? Thanks!

 

[FlyoverDRN]

Looking for some advice. As I said, the only visible damage are some scrapes on the rotors. I believe contact was extremely brief. A visual inspection fire not reveal anything. Should I have the motors tested to make sure the sudden drag did not happen them? Could an experienced person tell from the logs if they bound up are all? Thanks!

Just fly it. If there are issues, it will loose some serious flying time, due to the drone trying very hard to maintain a level flight, by fighting a bad prop or a bad motor.

 

[Greg-614]

Just fly it. If there are issues, it will loose some serious flying time, due to the drone trying very hard to maintain a level flight, by fighting a bad prop or a bad motor.

Good point, thank you. I threw new blades on last night and it seemed to perform fine. I did have a drop out of connection for the first time, but it restored a few seconds later.

 

[Made2Phly]

It also depends on the bridge. With my MP and M2P, I have had no problems under interstate highway-type bridges. I also flew under a metal decked bridge suspension bridge without incident.

But beware the old railroad bridge without a speck of concrete. I got some errors when underneath it, but the bridge was not too wide, and I was out the other side before any calamity. ensued.

 

[BigAl07]

Looking for some advice. As I said, the only visible damage are some scrapes on the rotors. I believe contact was extremely brief. A visual inspection fire not reveal anything. Should I have the motors tested to make sure the sudden drag did not happen them? Could an experienced person tell from the logs if they bound up are all? Thanks!

Chances are one of the "Idiot Alarms" will alert you if one (or more) of the motors are dragging any. I ran into what I call the beginnings of a Birds Nest and had a few strands of very finely pulled weed/grass wrap around a motor while in flight. I got a couple of "Motor Overload" (or something close to that) and landed. That's when I noticed the "debris" around the motor.

The Idiot Alarms/Switches are fairly robust on these systems.

 

[Greg-614]

Chances are one of the "Idiot Alarms" will alert you if one (or more) of the motors are dragging any. I ran into what I call the beginnings of a Birds Nest and had a few strands of very finely pulled weed/grass wrap around a motor while in flight. I got a couple of "Motor Overload" (or something close to that) and landed. That's when I noticed the "debris" around the motor.

The Idiot Alarms/Switches are fairly robust on these systems.

Thank you, they do seem to be able to tell you slot about what's going on. I appreciate the info!

 

[Greg-614]

It also depends on the bridge. With my MP and M2P, I have had no problems under interstate highway-type bridges. I also flew under a metal decked bridge suspension bridge without incident.

But beware the old railroad bridge without a speck of concrete. I got some errors when underneath it, but the bridge was not too wide, and I was out the other side before any calamity. ensued.

Thanks! I'll keep those in mind!

 

[GadgetGuy]

RTH wouldn't be triggered by a loss of GPS, it would just go into ATTI mode.

If you lose connection between the MA2 and the controller then you have a whole different set of issues to worry about if you're under a bridge at the time.

Never said loss of GPS would trigger RTH. Loss of signal under the bridge will trigger the loss of signal setting, which defaults to RTH. Hence, the detailed explanation of all the factors, which are exactly the ones I explained, not a whole different set of issues, as you claim!

 

[bp328i]

Never said loss of GPS would trigger RTH. Loss of signal under the bridge will trigger the loss of signal setting, which defaults to RTH. Hence, the detailed explanation of all the factors, which are exactly the ones I explained, not a whole different set of issues, as you claim!

So I guess here you would just be incorrect then? Because if you lose signal you're not traveling an extra 120 feet and the only other thing you mentioned was GPS.

Any GPS or signal issues require some 3 seconds of loss to trigger any change in flight. So, if traveling in max speed in N mode, you can travel 120 feet before RTH would be triggered. If the bridge width is shorter than that, it shouldn't be a problem.

RTH does not kick in after 3 seconds it takes 11 seconds after loss of signal, but once you lose signal the MA2 just stops and does nothing for 11 seconds (you can't fly blind or with no signal for 3 seconds). After those 11 seconds the MA2 will first move back 50 feet on it's original flight route to try to acquire the signal, if the signal is not re-acquire the MA2 will then RTH, Descend, or Hover (whatever the operator set as their fail safe).

The different set of issues I was speaking about was if you have the fail safe set to RTH and the height is above the bridge height (MA2 flies up into the bridge), Descend (water or something else below the bridge), Hover (hopefully you can get close enough to regain signal).

 

[GadgetGuy]

So I guess here you would just be incorrect then? Because if you lose signal you're not traveling an extra 120 feet and the only other thing you mentioned was GPS.

RTH does not kick in after 3 seconds it takes 11 seconds after loss of signal, but once you lose signal the MA2 just stops and does nothing for 11 seconds (you can't fly blind or with no signal for 3 seconds). After those 11 seconds the MA2 will first move back 50 feet on it's original flight route to try to acquire the signal, if the signal is not re-acquire the MA2 will then RTH, Descend, or Hover (whatever the operator set as their fail safe).

The different set of issues I was speaking about was if you have the fail safe set to RTH and the height is above the bridge height (MA2 flies up into the bridge), Descend (water or something else below the bridge), Hover (hopefully you can get close enough to regain signal).

You are twisting my words to suit your narrative. During the time signal loss is taking place for 3 seconds, the aircraft continues flight on the same course and at the same speed last recorded by the stick inputs. What hypothetically happens after 3 seconds if signal is not restored, is irrelevant, as long as signal is restored within 3 seconds, which is why I specified bridge widths to correspond with signal recovery within 3 seconds, based upon flight speed under the bridge. Any GPS loss has no effect upon the speed and has no relevant effect upon the direction of flight under the bridge, unless you are also tightly flying between bridge support structures with a major cross wind! Capiche?

 

[bp328i]

You are twisting my words to suit your narrative. During the time signal loss is taking place for 3 seconds, the aircraft continues flight on the same course and at the same speed last recorded by the stick inputs. What hypothetically happens after 3 seconds if signal is not restored, is irrelevant, as long as signal is restored within 3 seconds, which is why I specified bridge widths to correspond with signal recovery within 3 seconds, based upon flight speed under the bridge. Any GPS loss has no effect upon the speed and has no relevant effect upon the direction of flight under the bridge, unless you are also tightly flying between bridge support structures with a major cross wind! Capiche?

First: I'm not twisting anything.

Second: 3 seconds has NOTHING to do with the Mavic Air 2 or DJI Fly, there is no 3 second process.

Please show me one place DJI refers to this 3 second process you're speaking of in regards to the MA2.

There is no 3 second signal loss time, you have signal or you don't. If you can control your MA2 then you have signal, if you can't then you don't have signal, end of story. When signal is lost the MA2 does not continue on it's course, it stops.

Again, there is no 3 seconds with the MA2 and DJI Fly app, 3 seconds is the required disconnected time in the DJI GO4 app before RTH is initiated and since the MA2 doesn't use the DJI GO app your "detailed explanation" does not apply here and is completely incorrect in regards to the MA2.

If people could stop giving information that relates to the DJI GO 4 app in the Mavic Air 2 section, that would be great. That information is incorrect when it comes to the Mavic Air 2 and the DJI Fly app.

 

[GadgetGuy]

First: I'm not twisting anything.

Second: 3 seconds has NOTHING to do with the Mavic Air 2 or DJI Fly, there is no 3 second process.

Please show me one place DJI refers to this 3 second process you're speaking of in regards to the MA2.

There is no 3 second signal loss time, you have signal or you don't. If you can control your MA2 then you have signal, if you can't then you don't have signal, end of story. When signal is lost the MA2 does not continue on it's course, it stops.

Again, there is no 3 seconds with the MA2 and DJI Fly app, 3 seconds is the required disconnected time in the DJI GO4 app before RTH is initiated and since the MA2 doesn't use the DJI GO app your "detailed explanation" does not apply here and is completely incorrect in regards to the MA2.

If people could stop giving information that relates to the DJI GO 4 app in the Mavic Air 2 section, that would be great. That information is incorrect when it comes to the Mavic Air 2 and the DJI Fly app.

Glad we at least agree that 3 seconds is relevant on every other DJI aircraft. However, the 3 seconds has nothing to do with the GO 4 connection. It is hardwired into the drone and the RC connection. The GO 4 app connection is irrelevant to it. You could unplug your tablet and completely control the aircraft solely with the RC via VLOS, and no RTH will be triggered until you ALSO lose the RC connection for 3 seconds/11 seconds depending upon the aircraft. What would be the point of waiting in a hover for 11 seconds?

What proof do you have to support your claims that the MA2 is entirely different, other than that the loss of signal must be a full 11 seconds for failsafe RTH to be initiated? I can find nothing to support your claim that the aircraft comes to an abrupt full stop the instant signal is lost (physically impossible, as the braking distance would come into play, giving you further distance until a full stop). On the contrary, it should continue flight with the existing stick inputs for a full 11 seconds, rather than just 3 seconds, making any "under bridge flying" even safer. The whole point of the 11 second delay is to continue course and pass any obstruction temporarily blocking signal (like passing behind a building) without unnecessarily initiating failsafe RTH, and not to have the aircraft first hover needlessly for 11 seconds, before retracing the last 50m!

Failsafe RTH
If the Home Point was successfully recorded and the compass is functioning normally, Failsafe RTH automatically activates after the remote controller signal is lost for more than 11 seconds. The aircraft will fly backwards for 50 m on its original flight route, and then enter Straight Line RTH.

https://dl.djicdn.com/downloads/Mavic_Air_2/20200511/Mavic_Air_2_User_Manual_v1.0_en.pdf