We have a theory, if a drone cannot land safely, it has no business flying. Assuming your drone does fly safely, you can manually manage the flight and landing, or you can utilize a built-in feature for many machines, RTH. Just what is RTH? Simply enough, RTH stands for Return to Home.
RTH is an automated flight feature that sounds simple enough, but there is more to it than just hitting a button, let’s talk about the capabilities of RTH to help you land safely.
What is RTH?
Return to home as a concept is fairly easy to understand, computationally, however, there is a lot going on. For starters, where is ‘home’ exactly?
The RTH function on your drone can be a lifesaver. Particularly if you lose sight of your machine in the air (which you should never do, remember those FAA rules) or your remote loses connection to the drone. A tap of a button on the remote or in the software should soar your drone back to a home location.
As I said, your drone needs to know where home is. This can be done in one of two ways, fundamentally. Your drone may be equipped with tech like GPS that records your take-off location, the drone then returns to that point. Other drones may track your travels, then manage to reverse your flight back to where you started.
On our daily flier for the longest time, the DJI Mavic Pro, a combination of GPS and image capture is used to determine where home is. When it leaves the ground it sets the GPS location, it then is able to see forward and downward. When the Mavic Pro returns to home, it narrows in on the GPS coordinates and then does its best to match the images as it comes in for a landing. I dare say, it is very accurate, almost always landing within about ten inches of my launch points.
A few drones use your remote or another physical beacon to hone in on, this for both location awareness and for landing accuracy.
If you are flying for pay, or any other form of compensation, you must operate under a different set of rules and possess a commercial drone license. We call it the Part 107, it’s not too hard to get, but it will take some time to learn all the rules. We want to help you learn the rules and get your commercial license, check out our drone pilot training material.
How to use RTH
For most drones and situations the default RTH trigger is a button. Many drones use RTH for safety as well, if your battery is low or you lose connection to your remote control, the drone can fly itself home.
Watch out for that tree!
You might be wondering about mid-air collisions when your drone is autonomously soaring back to its home spot. Particularly of concern if your drone does not have obstacle avoidance sensors on board.
The most common obstacle avoidance technique for RTH is to set a specific altitude. Many drones default to 20 or 30 meters, about 60 or 90 feet above the ground. Living in the Pacific Northwest of the United States, I try to go even higher, if possible, we have some massive trees around here.
Depending on your flight location, the idea is simply to ensure that your RTH altitude is greater than the tallest tree or building in your flight area.
Are you moving?
I often fly in a large area with hiking trails, you might have your drone following you while you snowboard or mountain bike. It would suck if your drone decided that the top of that big hill was home and took off without you. There are solutions available that differ by drone, but the idea is to frequently update your home location. You could turn off RTH for that flight as well.
Also take note of where your drone will end up if it does head for home, rather, will you be able to see it make it all the way back? The FAA says you must always be within line-of-sight of your drone, if your set home location is behind some trees or on the other side of a building, you cannot legally utilize the RTH feature of your machine. Sorry. Learn more about the FAA’s rules from the links below:
Warning, look up!
The biggest problem I have with RTH capable drones is when they cannot be overridden. I had an incident once where my flight was to hover a few feet from the ground, then land. I just needed a couple photos of the machine in the air. The low battery warning came on, which was fine, I still had ten times the juice I needed to land, but the RTH kicked in and the drone flew up.
It seems ludicrous that a drone that is 5 feet in the air and just 3 feet over from its Home location should shoot straight up to 60 feet just to move over and come back down, but that’s what happened. Or, that is what would have happened, I was under a tall tree canopy, probably forty feet above my flight plan. If this drone would have let me bypass the automatic RTH and manually land, we would have had no issues at all. Long story short, I caught the drone as it plummeted to the ground.
The lesson is easy, your RTH elevation and flight path must both account for flying over objects and staying under objects. Keep it safe out there.
A few great RTH drones
Before we call it quits for the day, let’s look at a few of the best drones for RTH flying.
DJI Mavic 2 Pro and DJI Mavic 2 Zoom
The recently announced DJI Mavic 2 series of drones includes the Pro and Zoom models. The 1-inch camera on the Mavic 2 Pro is one of the best we’ve seen, and the 2X optical zoom on the Mavic 2 Zoom is a feature that few other drones can offer. From there, aside from a couple Quickshot modes, these two drones offer the same flight experience. Equipped with OcuSync 2 and all-direction obstacle avoidance sensors, this will be one of the safest RTH experiences you can find.
Related reading: DJI Mavic 2 review
DJI Mavic Air
There is a good chance you are going to see this drone a lot across our site. Like the DJI Mavic Pro before it, the new Mavic Air packs in the best flight features that DJI has to offer, save for Ocusync, but that’s another story. Utilizing the same DJI GO 4 app as most other recent DJI drones, the Mavic Air defaults to a 30 meter RTH altitude, and the machine is aware of how far it is from its home point so can automatically engage RTH when your battery gets to a critical level.
While airborne, you can enjoy the updated 4K camera, the new Quickshot flight modes and more from this $799 drone. Update to the DJI Mavic Air Fly More combo for $999 to get additional batteries and more.
DJI Mavic Pro
Update: DJI has released the DJI Mavic Pro Platinum. This newer version is more efficient and quiet in the air, but is mostly the same drone.
DJI really has done a great job with the Mavic Pro. There are limitations, but as an all around flying machine, balancing features with ease of use, portability, camera quality and price, I can think of no better. The combination of GPS and visioning systems provides accuracy that exceeds my needs, landing itself safely inside my portable heli-pad each and every time.
DJI has the new Mavic Pro Platinum shipping to users now, we have not been informed of any adjustments to the RTH functionality, but we’ll be sure to test when we have our hands on a unit.
Yuneec Typhoon H
Update: Stay tuned for the Yuneec Typhoon H Plus. The updated drone was announced at CES 2018, and will hit the market later this year.
The Yuneec Typhoon H is a fun and stable flying hexacopter drone. We almost put the newer and more capable Yuneec H520 on this list, which is an impressive commercial drone that packs in some very advanced flight automation. At InterDrone 2017 we watched a demo of the H520. After setting the flight plan in the remote control, the drone handled the rest, taking off, flying a grid and landing back in place all on its own.
The Typhoon H is older, we have to admit, but packs most of the same tech as the H520 in terms of RTH functionality. GPS and more bring that drone back to land close to its take-off location. The Pro model packs Intel RealSense visioning systems to ensure no mid-air collisions as well.
Check out the Yuneec Typhoon H for $799 today.
Yuneec Typhoon H Plus
More recently, Yuneec released the Typhoon H Plus. The newer model is a rebuild of the original Typhoon H in almost every way. The larger, more powerful Typhoon H Plus, with updated 4K camera enjoys a new remote and updated software as well. All considered, the Typhoon H is a great drone, but the Typhoon H Plus is an upgrade that enables new uses for your flying needs.
Check out the Typhoon H Plus for $1899 with Intel RealSense today.
Looking at drone flight a little different than most manufacturers, AirDog builds a machine that compliments your outdoor lifestyle. There are many different automated flight modes, plus some great manual tracking modes that most all fall back on a home location for safe landing. You can see the drone in action a little when we demoed it just ahead of their Kickstarter launch.
The AirDog ADII is $1599.
DJI Phantom 4 Pro
If you thought the RTH and visioning systems were good on the Mavic Pro, wait until you try the Phantom 4 Pro. Obstacle avoidance sensors are deployed on all sides except upward, so you are almost certain to not crash during automated flight.
The Phantom 4 Pro, as with most in the Phantom drones line, is a great machine to consider beyond the scope of RTH functionality. Check out the DJI Phantom 4 Pro for $1319 or add a display to the remote in the Phantom 4 Pro+ for $1549. Regular price is $1499 and $1799, watch for sales often around $1300 and $1600.
Hubsan may be known for it’s affordable toy-class machines, but the H501S Brushless is well beyond the average of their entry level fliers. GPS and other functions make for a reliable drone that has a decent camera, but is still a little shy of capturing the same quality as the rest of the drones on this list.
Check out the Hubsan H501S Brushless for $175 today.
We’ve been flying the GDU O2 lately, and have been impressed with the results. This compact machine is designed with propeller arms that slide in and out of the body for transport. It is a solid unit that flies quite well. We have not yet tested it at great range, but for a hundred yards or so it returned to home without issue, landing about 6 feet from its take-off point.
Check out the GDU O2 for $732 on Amazon today.
Time to go home
Tap that RTH button, it’s time to wrap up this article and head on home. Be sure to look into your settings when you fly, automation is fun and all, but you are still responsible for your drone making it back to earth safely.
Have any fun RTH success or failure stories you’d care to share? Hit the comments below.