Get more from your Mavic
The largest Mavic community in the world
Join Us Now

So what could go wrong?

alanh

Member
Joined
Jul 24, 2018
Messages
18
Reactions
3
Location
Central Texas
This is a hypothetical scenario. The Mavic Pro is to be launched from a back yard surrounded by 55’ high trees. There is an opening in the trees sufficiently large to safely reach open sky launching vertically. The flight plan is to climb to 120 meters (396’) and then proceed horizontally for one mile against the wind, which is light and gusting to 5 MPH on the surface. The flight path will be mostly-open ranch land, with random groves of trees, none of which will exceed 80’ in height, and over some small lakes. The terrain is virtually flat. The flight will take place totally over pilot’s private property, so there are no privacy issues or risks to people. Restricted air spaces are not an issue. The flight path will be visually-checked while outbound to endure no obstacles exceed 396’ in height anywhere on a potential return path. Video will be made of ranch cattle during the return flight, during which time the craft will descend to as low as roughly 50’ AGL. DJI Go 4 will be running on a Samsung 9.7” Galaxy Tab S2.

Settings:

RC Signal Lost = RTH
P Mode
Enable Obstacle Avoidance = On
Landing Protection = On
RTH Obstacle Detection = On
Smart Return Home = On

I’m not trying to wave a red flag at the VLOS crowd – this is intended to be strictly a technical question. What is the worst that could happen and how likely is it? What else could be done to mitigate the risk?
 
Last edited:

dirkclod

Moderator
Staff Member
Premium Pilot
Joined
Oct 12, 2016
Messages
19,381
Reactions
42,268
Age
66
Location
Amory , MS
I don't think you would hit 1 mile if there is foliage on the tree's using Go app anyway .
And welcome to the forum .
 
  • Like
Reactions: Former Member

Mossiback

Well-Known Member
Joined
Oct 3, 2017
Messages
4,022
Reactions
3,101
Age
67
Location
Brier, WA USA
• The worst that can happen: Since your description means you will not have visual of your MP or the airspace, your MP may be hit by a low-flying helicopter, crop duster, birds, or any other yahoo sharing the airspace.
• How likely is it? Not very.

What is more likely is you will lose connection due to distance and trees and have to rely on RTH to bring it back.
 

ac0j

Well-Known Member
Joined
Sep 17, 2017
Messages
2,809
Reactions
2,267
Age
58
Being in side a stand of large trees, as dirklod suggests will dramatically affect range. Can you find a take off point out in the open?
 
  • Like
Reactions: conchman

wytnyt

Well-Known Member
Joined
Nov 16, 2017
Messages
1,529
Reactions
886
Location
Va.
agreed,i have a row of trees about 100 tall and only get like 3/4 mile before signal degrades,los is critical for long distances
 

Mossiback

Well-Known Member
Joined
Oct 3, 2017
Messages
4,022
Reactions
3,101
Age
67
Location
Brier, WA USA
Use Litchi. Design it as a waypoint mission. Launch and forget. No worries about disconnects.
The main problem with Litchi in this case is that the OP wants to capture video of cattle on the way back. Unless they will be in a predetermined position it would be hard to use a waypoint mission for this.
 
  • Like
Reactions: Former Member

Lapeer20m

Well-Known Member
Joined
Feb 28, 2017
Messages
1,293
Reactions
1,623
Location
Southeast Michigan
Mavic transmission signal easily goes miles over open terrain.

I just moved to a new place that has trees much like you describe. Transmission range is less than 1 mile for me. I was surprised how much the trees block the signal.
 

alanh

Member
Joined
Jul 24, 2018
Messages
18
Reactions
3
Location
Central Texas
Thanks for the welcome to the forum, and thanks for the valuable information. You have a great community here. I'm not surprised that 2.4 GHz doesn't bend well around trees. I also expect the aftermarket range extenders wouldn't help much in this scenario, right? So given that signal loss is likely to happen, how reliable is signal-loss-RTH? I've been very impressed with the landing accuracy of RTH with the optical assist, but don't have any experience with signal loss. Having had a programming career, I'd guess that the algorithm to detect signal loss and invoke RTH is extremely reliable, and the problems from RTH stem mostly from obstacles encountered in flight.
 
  • Like
Reactions: tstillman

Former Member

Well-Known Member
Joined
Dec 20, 2016
Messages
13,985
Reactions
13,059
Location
Duluth, Georgia
Thanks for the welcome to the forum, and thanks for the valuable information. You have a great community here. I'm not surprised that 2.4 GHz doesn't bend well around trees. I also expect the aftermarket range extenders wouldn't help much in this scenario, right? So given that signal loss is likely to happen, how reliable is signal-loss-RTH? I've been very impressed with the landing accuracy of RTH with the optical assist, but don't have any experience with signal loss. Having had a programming career, I'd guess that the algorithm to detect signal loss and invoke RTH is extremely reliable, and the problems from RTH stem mostly from obstacles encountered in flight.

Just have to ask, do you have DJI Refresh?
 

ac0j

Well-Known Member
Joined
Sep 17, 2017
Messages
2,809
Reactions
2,267
Age
58
Thanks for the welcome to the forum, and thanks for the valuable information. You have a great community here. I'm not surprised that 2.4 GHz doesn't bend well around trees. I also expect the aftermarket range extenders wouldn't help much in this scenario, right? So given that signal loss is likely to happen, how reliable is signal-loss-RTH? I've been very impressed with the landing accuracy of RTH with the optical assist, but don't have any experience with signal loss. Having had a programming career, I'd guess that the algorithm to detect signal loss and invoke RTH is extremely reliable, and the problems from RTH stem mostly from obstacles encountered in flight.

In MOST cases the RTH when signal loss works pretty good, UNLESS there is a compass problem.
 
  • Like
Reactions: Former Member

UAVNV

Well-Known Member
Joined
Jul 19, 2017
Messages
232
Reactions
145
Age
44
i did this using litchi waypoints, anticipating signal loss to the controller. story below:

I wanted to capture the view from above the trees, without risking loss of transmission with manual flying. This is where Litchi shines. Satellite coverage was spotty due to the canopy of trees.

I had the map cached in Litchi previous to the trip, when I found a suitable location, tested satellites above the canopy, flew just above the tree line to tag the lowest vertical height I was comfortable with, and proceeded to create waypoints right above my location.

 

alanh

Member
Joined
Jul 24, 2018
Messages
18
Reactions
3
Location
Central Texas
i did this using litchi waypoints, anticipating signal loss to the controller. story below:

I wanted to capture the view from above the trees, without risking loss of transmission with manual flying. This is where Litchi shines. Satellite coverage was spotty due to the canopy of trees.

I had the map cached in Litchi previous to the trip, when I found a suitable location, tested satellites above the canopy, flew just above the tree line to tag the lowest vertical height I was comfortable with, and proceeded to create waypoints right above my location.

Nice. But as Mossiback wrote, can't anticipate where those cows will be, so need real-time control.
 

Marko9219

Well-Known Member
Joined
May 26, 2017
Messages
486
Reactions
447
Age
67
The main problem with Litchi in this case is that the OP wants to capture video of cattle on the way back. Unless they will be in a predetermined position it would be hard to use a waypoint mission for this.
With the details unknown to me, perhaps he could program the mission to stop, shoot a 360 pano then repeat as needed to see the areas needed. I dunno Just a thought
 

RoboticTundra

Well-Known Member
Joined
Apr 11, 2018
Messages
161
Reactions
58
Age
61
RTH does not, in my experience, fly to directly over the landing spot and then descent straight down. It will fly to the approx location +/- about 10 meters, begin descending, and adjust as necessary. If the trees are tight in to the landing area it may have difficulty.
 

colinfowler

Well-Known Member
Premium Pilot
Joined
May 14, 2017
Messages
886
Reactions
549
Age
69
Location
UK heathrow west london
This is a hypothetical scenario. The Mavic Pro is to be launched from a back yard surrounded by 55’ high trees. There is an opening in the trees sufficiently large to safely reach open sky launching vertically. The flight plan is to climb to 120 meters (396’) and then proceed horizontally for one mile against the wind, which is light and gusting to 5 MPH on the surface. The flight path will be mostly-open ranch land, with random groves of trees, none of which will exceed 80’ in height, and over some small lakes. The terrain is virtually flat. The flight will take place totally over pilot’s private property, so there are no privacy issues or risks to people. Restricted air spaces are not an issue. The flight path will be visually-checked while outbound to endure no obstacles exceed 396’ in height anywhere on a potential return path. Video will be made of ranch cattle during the return flight, during which time the craft will descend to as low as roughly 50’ AGL. DJI Go 4 will be running on a Samsung 9.7” Galaxy Tab S2.

Settings:

RC Signal Lost = RTH
P Mode
Enable Obstacle Avoidance = On
Landing Protection = On
RTH Obstacle Detection = On
Smart Return Home = On

I’m not trying to wave a red flag at the VLOF crowd – this is intended to be strictly a technical question. What is the worst that could happen and how likely is it? What else could be done to mitigate the risk?
I would test your RTH to see if it returned accurately and safely. Set RTH altitude with a good separation over your trees.
You can take over the landing if it dose not look safe or accurate.
 
Lycus Tech Mavic Air 2 Case

DJI Drone Deals

1. Mini SE - $299
2. Mini 2 - $449
3. Air 2 (renewed) - $649
4. Air 2s - $999
5. FPV Combo - $1299
6. Mavic 2 Zoom - $1349
7. Mavic 2 Pro - $1499

New Threads

Forum statistics

Threads
108,309
Messages
1,282,504
Members
139,113
Latest member
soniya45