Although this mode is not specific to DJI drones only, we will look here at the specifics of the on-board system at the Chinese giant. Return to Home is a useful safety feature present on DJI drones.
However, it is possible that the way this system works is misunderstood by first-time users, which unfortunately can sometimes lead to drone crashes. which could have been avoided.
You should have a better understanding of this basic functionality which equips a large majority of drones today, and not only DJI.
This is a feature well worth detailing and understanding as it just might save your day one of these days.
So we’re going to take an in-depth look at this system and how it works.
There are 3 types of “returns home” at DJI, all of which have 3 different causes:
This type of RTH is the one best avoided and easiest to anticipate. As the name suggests, this RTH is triggered when the DJI Intelligent Flight Battery is depleted to the point of affecting the drone’s return to base.
When this happens, a notification will appear on your screen in the DJI GO/4 app and the drone will automatically start climbing to your chosen height (RTH altitude) and automatically return if no action is taken after a 10 second countdown. If the battery power is very low, the drone will land automatically and this cannot be overridden by the pilot if the battery is really too low (less than 8% in general).
Remember to set alerts in your DJI Go 4 App! A first has 30% battery to start your return and a second around 15% to start the descent and land the machine. These figures, given as examples, are of course to be put into perspective if your return is facing the wind and if you are flying far in distance!
You can also assign shortcuts to the buttons on the bottom of your remote controller for easier access to battery data in flight.
Failsafe RTH occurs when your drone loses signal for 3 seconds or more when using the remote control or 20 seconds when using Wi-Fi.
When it kicks in, it will do one of three things, depending on how you’ve configured it (This is still adjustable through your DJI Go 4 App).
First of all, if you have it set to RTH it will rise to the selected RTH height and start coming back towards you and once you get the return signal you can cancel it and take control again. Second, if you have it set to “Hover” or “Hover”, your drone will just hover at its current position, so you can walk towards it and restore your signal.
However, if you are unable to restore your signal and the Battery RTH is triggered, the drone will return to Home or Land depending on your Battery RTH settings. Third, it can be set to land, so it will only land in its current position.
I personally only use (and advise you to do the same) the automatic return to Failsafe, especially since I own the Mavic Air, which very (too?) often loses the signal in flight in urban areas. The second option is not very useful in my opinion and the third is not possible if you are flying over water…
This is the only form of Return Home that I personally use, in case of loss of signal in flight. I usually let it come back for a bit and cancel it to regain control as soon as the video feedback comes back on my smartphone.
This is a user-triggered RTH when you press the RTH button on your remote or in the app. Once the button has been pressed, the drone begins its flight back to its home point.
It can be stopped at any time by pressing the Flight Pause button on the remote control or by pressing the Stop icon in the app.
If you are flying the Phantom 4 Pro or Advanced, the drone will mimic its flight path for approximately 30 seconds before beginning its ascent and returning directly to you.
You have to remember that if your drone is within 20 meters of you when you press the RTH button (or if you lose signal) it will land right where it is, but if the landing zone is dangerous, it will try to find a safe place to land or just stay at a low height until the pilot takes control and initiates the landing manually.
RTH Settings in DJI GO/4
To the right of the “Home Point Settings” text are 2 icons. The first (with the arrow) will position the RTH point at the same place as the position of your drone at takeoff. The second (with the person) will position the RTH point at the same place as the person wearing the radio control.
This is convenient if you change position during the flight. Watch out for your Home Point if you drone from a boat!!! Your GPS location coordinates should change.
Sometimes you will surely not be able to get more than 10 satellites to set your home point (the bar does not turn green and DJI Go 4 does not want to place your point on the map) and it will be difficult for you to set your home point.
To avoid “wasting” your dear battery and/or having to restart the machine, you can make it take off without having set the home point and as soon as you obtain a good GPS signal (the bar turns green), remember to adjust by pressing the button with the person which will adjust the RTH point to where the remote control is located.
DJI Go 4 Settings
Now that we’ve looked at the different types of return-to-home modes available, let’s take a look at the DJI Go/4 settings that affect this infamous RTH.
Vision Positioning System
DJI VPS needs to be enabled if you want to use Landing Protection and Precision Landing. The only real reason to turn off this feature, which primarily helps with flight stability, is if you plan to fly over a reflective surface like water, as light reflecting off the water tends to skew the data received by the sensor.
This is another useful setting as the drone will scan the ground before landing to ensure the landing area is appropriate. If not satisfied, the drone will try to find a more suitable landing area.
This is when the drone stops briefly after takeoff and takes a picture of its landing area so it can be more accurate when it returns, matching the image to what the sensor sees below it.
The RTH Obstacle Check setting
This means that your drone will check for obstacles during its return and if it detects one, the drone will ascend to avoid it. If you have enabled this setting, it means your bird will still check even if you have disabled the Obstacle Avoidance feature for the drone.
All of these settings are enabled by default and it’s generally a good idea to keep them enabled at all times. It’s worth checking every once in a while that you haven’t accidentally turned one off. The Spark is an exception to the above though, as it doesn’t have these settings, just a single “Sensor State” setting, which allows the sensors to be enabled or disabled.
I personally deactivate a good part of these options (except the VPS) because I most often launch manually and not from the ground.
How to use DJI Homecoming safely?
First of all, you should ALWAYS follow a pre-flight routine before setting off and setting your maximum altitude back home is one of the most important points!
You must remember to register your “Home Point” and for this, it makes you at least 10 GPS satellite connections. Remember to activate the 3G/4G connection too in order to have access to the map to check if the point is in the right place! Yes DJI in the past has experienced bugs that placed the RTH point miles away from the remote control…I’m not drawing you a picture when the pilot hit the RTH button in mid-flight…
Your Home Point can be the location of your drone before takeoff or it can be where your remote is during flight, always check that it is placed correctly on the map.
Be sure to set your homecoming altitude so that it is higher than the tallest obstacle around you. Usually, I set it at 10m above the highest obstacle, if in doubt it is better to see too high than not enough (respecting the maximum authorized flight height of course). Now your RTH should be safe to use.
Keep in mind here that this is above all in-flight assistance and that problems can occur in flight (and yes, technical problems unfortunately happen with electronics…).
There is no substitute for good manual piloting and apart from the rare cases where you will lose the signal, you should always keep your drone in sight and be able to bring it back to base manually! Do not take advantage of the assistance to rest and not to develop your pure driving skills, it is heresy in my opinion.
Hoping to have helped you. Good flight !