What is Atti Mode?

'Atti Mode' is DJI term for Attitude Mode - where your drone's GPS system is disable so it will not remain in a stable hover situation, allowing it to be subject to the effects of wind drift. It's a CAA requirement that we assess each RPAS Pilot's ability to safely operate their drone when GPS signal is lost, and an Atti Mode situation arises. The goal is for you to develop skills to operate your drone safely if it reverts to Atti Mode. You will need to perform a range of tasks within Atti Mode.

Not all drones will have the functionality to manually select Atti Mode, including the DJI Mavic models.

Operating under trees, near buildings and structures, or near high tension power lines can cause signal loss, as well as a failure with the drone's GPS system, and it can happen at any time so it is important to practice. We recommend at least 6-8 batteries worth of practice to become proficient. We can provide instructors if you require tuition.

Why the CAA assesses ATTI mode

Most people can fly their multirotor quite adequately while the GPS stabilisation system is working. The question is what happens when that system fails through shielding, interference, or a fault. It does not happen often, but it can and does happen. As the pilot you must be capable of operating your drone at a reduced level of automation, and getting it to a place where it can safely land and be retrieved.

Because of this, the CAA requires that every flight assessment using a GPS stabilised multirotor includes a portion flown in the aircraft's basic flight mode.

In ATTI mode, instead of holding a fixed GPS or vision-sensor position when hovering, the drone simply tries to stay level and at the same altitude. If there is any wind, the drone will move with it and you will need to counteract that with the controls to hold position.

Some drones cannot manually select ATTI mode - including the DJI Mavic, Phantom and Spark series - yet they will still drop into it on a GPS failure or magnetic interference. To prepare for your assessment you need access to a multirotor with selectable ATTI mode, or an equivalent mode.

How to practise ATTI mode

This is not something you can master in a couple of flights. Build up gradually:

• Choose a large area well away from buildings and people, on a calm day to begin with. Increase the wind speed you practise in as your skills improve.
• Make your take-off and landing in P mode for the first few flights, then switch to ATTI mid-flight.
• Use small, frequent control inputs as soon as you detect drift. Correct early rather than letting the drone drift and then trying to arrest it.
• If you get into difficulty, switch back to P mode.
• Practise hovering over and moving between cones laid out in a 20 m square. Any visible object will do if you do not have cones.
• Practise flying in all orientations, including with the drone coming towards you, so you get used to compensating for drift in every direction.
• Once you are comfortable in all orientations, progress to a horizontal figure of eight around two cones. That gives you practice in left and right turns and in controlling the drone as it flies both towards and away from you.

The flight test can be a stressful time, but it need not be if you are well prepared.