Editor’s Note: This is a guest post by Chris Anson. Check out his work right here.
Here’s the challenge: Your drone can be flying along and all of a sudden you lose GPS signal or some other reason and your drone app tells you that it has changed to ATTI mode or it tells you that GPS mode is no longer working and tells you to switch to ATTI mode. What do you do? When this happens in an emergency situation and the pilot doesn’t have any experience in flying in ATTI mode, it often leads to crashes.
What is ATTI Mode & Why is it Important?
ATTI mode is a flight mode that a DJI drone can change into if a good GPS connection is lost. On some models of DJI drones, it is a physical switch that can be flipped that puts the drone into ATTI mode. In either case, ATTI mode disables the GPS, GLONASS and obstacle avoidance systems in the aircraft, but the aircraft will typically maintain altitude and attitude.
How Does this Affect Me Piloting the Drone?
What this means is the pilot has to compensate for the wind. It will drift with the wind while maintaining a stable attitude and altitude.
The drone should maintain altitude, though not as accurate as GPS, the pilot will have to keep an eye on that as well. In GPS mode the pilot can be hands off of the controls. The drone will stay pretty much where it is. In ATTI mode, hands off will allow it to drift on its own. Same goes for keeping an eye on altitude.
Does this Ever Happen in Real Life?
Yes, it happened to me last week when I was flying near the Fremont Bridge in Portland Oregon. This is a massive metal structure and metal things this size can affect the aircraft’s GPS and Compass. I was cautious.
In setting up to shoot this location, I found a launch/landing spot about 300 yards from the bridge and set up my aircraft. I started everything up and did a sensor check. My IMU and Compass gave me excellent readings so I was good to go.
On my first 3 sets of batteries, I had no problems and captured both video and panoramas without a hitch. On my final flight of the day, I was shooting 360 Panoramas. I positioned myself about 800 feet from the bridge and started my panoramas. As the mission began I watched the aircraft drop about 30 feet straight down. That made me take a quick breath. I checked the app and didn’t see any problems so I continued recording. Once the panorama was complete, I started back to the landing spot.
On the way, I got a warning in the Go 4 app that the aircraft had lost GPS and that I needed to switch to ATTI mode. At the same time, I saw the drone start to tilt at an odd angle and then received a compass error. I immediately switched to ATTI mode. There was a medium wind and so the aircraft started the quickly drift back towards the bridge. Because of my practicing flying in ATTI mode, I was able to regain control of the aircraft, bring it back and land it safely. Had I not known how to control the aircraft in ATTI mode I may well have lost the drone into the river.
When I landed drone and checked the sensors, GPS, Gyro, and Compass were all disabled. I shut the drone, remote and iPad down and restarted everything. On restart, the GPS and Gyro were working in the excellent range, but the Compass required recalibration. I tried recalibrating at the location, but there was too much interference. I was able to recalibrate and test everything upon return to my home office and everything was working correctly again.
How do I Practice ATTI Mode?
If you have never flown in ATTI mode and want to start practicing, here is what I suggest to my clients and friends. First be aware that in practicing this you might crash your drone. You must take on that responsibility. If you are willing to take that risk then read on.
My first suggestion is to find out if you know someone who has experience in flying in ATTI mode and can help you. This can really accelerate the process. In either case, the next thing to do is find a big open field with few trees and tall obstacles nearby and do it on a calm wind day. Take the aircraft off in GPS mode and pick an altitude where you have some height, but that you can clearly see the aircraft and how it responds to your stick commands. Now orient the aircraft with the nose of it away from you. This orientation will help you as you learn to enter the correct stick commands to offset the drift from the wind. This way, pushing the right stick forward it will go forward and away from you. Pulling the stick back towards you will bring the aircraft towards you, etc.
Now begin by switching your aircraft into ATTI Mode and see what the aircraft does and how it drifts. Do this only for a few seconds before you switch back into GPS Mode. This will give you an idea of how the aircraft is drifting. Be sure you can switch back and forth without looking down at the controller before moving on. This is really important because if you find yourself in trouble or just get disoriented then you can switch immediately back into GPS mode, bring the aircraft back near you and start again. You may also find this process to be stressful at first, so be patient and take your time. It takes a lot of concentration, so if you get tired land and take a break before continuing.
Start out practicing for a few seconds and as you get better and more confident, increase the time.
Fly safe and have fun!
Chris Anson is a FAA licensed Part 107 Pilot. With a background in landscape photography and video, at the beginning of 2017 he turned his focus to taking them into the air using a drone. He also earned his FAA Part 107 Drone Certificate allowing him to do commercial work. His transition to flying drones was aided by having flown large 6’ rotor span radio controlled helicopters for 5 years. His focus is working as a contractor for other companies both piloting as well as piloting his own equipment and capturing stock videography and photography. He currently flies a DJI Inspire 2 drone with Zenmuse X5S camera. See examples of his work here http://www.tag-drones.com/