There are three different heights values to be aware of when planning and flying a mission with the Phantom 4 RTK drone: Mission Height, Maximum Altitude, and Return-to-Home Altitude.
First, be sure to check the airspace and DJI "altitude zones" before you get on-site and while planning your mission to make sure that none of these three heights surpass the airspace ceilings set by the Federal Aviation Administration (FAA).
This is "the altitude of the aircraft during the operation", which you set during mission planning. The Mission Height is set in meters, regardless of other controller settings.
In the US, FAA regulations prohibit Part 107 drone pilots from flying above 400ft (approximately 120m). Similarly, the Civil Aviation Safety Authority (CASA) regulations in Australia prohibit drone flights above 120m.
While flying, you can see the current drone height (vertical distance from the drone to Home Point) in the lower part of the screen, marked H.
In the image below, the current height is 0.0ft because the drone was not in flight.
This is the maximum altitude the controller will allow the drone to reach during its missions. Unlike the Mission Height, the Maximum Altitude is set in feet.
Remember that Part 107 pilots cannot fly above 400ft (about 120m), so do not set the maximum altitude any higher than that unless you have explicit authorization from the FAA or other environmental reasons to do so.
The controller will show a message if you reach maximum altitude: "Maximum Flight Altitude reached. Adjust your altitude using Aircraft Settings if required."
You can change the Maximum Altitude in the Aircraft Settings from the Fly screen.
Please note—If the GNSS signal is weak and the Vision System is activated, the drone will not go higher than 26ft/8m. With a weak signal but deactivated Vision System, the altitude will be restricted to 98ft/30m.
The Vision System is the collective name for the sensors on the drone body, which use ultrasound and image data to help keep the drone in its current position, as well as scan for obstacles.
This is the altitude at which the aircraft will return to the Home Point either at the end of the mission or when you call the drone back home. This article details how to change the Home Point.
The Return-to-Home altitude is more relevant for manual flight missions. If you manually fly your drone, please exercise caution and turn on the obstacle avoidance system for safety.
For non-manual flight missions, the Return-to-Home altitude is something to check if you are having issues with airspace ceiling restrictions and cannot determine the cause.
You can change the Return-to-Home altitude in the Aircraft Settings from the Fly screen.
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