I see there is an RTH altitude setting in DJI Fly and it is currently set to 30m. Is 30m good or should I change it? What exactly happens when the drone uses Return to Home — does it go to 30m first and then fly home? What happens if there is a tall tree or building between the drone and the homepoint?
RTH altitude is the altitude your drone climbs to before flying in a straight line back to the homepoint. The default 30m is dangerously low for most environments and should be changed before your first flight.
What happens during RTH: the drone checks if it is below the RTH altitude — if so, it climbs to RTH altitude first. Then it flies a straight line at that altitude directly to the homepoint. Then it descends to land.
The danger: the drone does not navigate around obstacles during RTH — it flies a direct straight-line path. If any obstacle between the current position and the homepoint is taller than the RTH altitude, the drone flies directly into it.
Recommended settings by environment:
Set RTH altitude every time you fly from a new location — the right value is specific to the obstacles at each site.
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How to set RTH altitude in DJI Fly: tap the three dots in the top right of the main screen to open settings, select the Safety tab (shield icon), and find Return to Home Altitude. Change from the default 30m to an appropriate value for your location.
Also confirm the homepoint has been locked before takeoff. In DJI Fly, the homepoint shows a home icon with a checkmark and the GPS coordinate on the map when it has been acquired. If you take off before GPS lock is established, RTH may not navigate correctly — the homepoint could be set to an incorrect position or not set at all.
Many pilots use a consistent high altitude like 100m as their default to avoid accidentally leaving a dangerous low setting in place from a previous session. The downside is a longer climb during each RTH event, but that cost is always less than a crashed drone.
What happens when RTH altitude is too low is not theoretical — it is one of the most common causes of drone loss. The scenario: you lose signal while flying 200m away at 50m altitude with buildings between you and the launch point. The drone waits 3 seconds then initiates RTH. It climbs to 30m. The buildings are 40m tall. The drone flies directly into the building at 30m altitude while trying to return.
A 100m RTH altitude would have cleared all obstacles on the same path. The conservatively high RTH altitude is your primary safety net against signal loss events. Set it as high as local regulations allow. The cost of a high RTH altitude is a few extra seconds of battery use on each return. The cost of setting it too low can be a lost drone or worse, a crash into a building.
Technical behavior details: if the drone is already above the RTH altitude when RTH triggers, it does NOT descend to RTH altitude — it maintains current altitude and begins flying home immediately. RTH altitude is a minimum, not a fixed target. Flying at 80m with RTH altitude at 30m means the drone returns at 80m if RTH triggers.
RTH altitude also applies during low battery events: battery RTH calculates the battery percentage needed to return from the current position at standard speed and triggers RTH when reserve is reached, climbing to RTH altitude before flying home. The calculation is based on a straight-line return — maneuvering en route or headwind can consume more battery than the calculation expected. This is why landing early when battery reaches 30-40% is safer than relying on the low battery RTH trigger to manage the landing precisely.
Mountain and complex terrain: RTH altitude needs to account for the maximum terrain elevation difference between you and the homepoint, not just static obstacles. If you launch from a valley floor and fly over a ridge that is 80m higher than your launch point, your RTH altitude needs to be above 80m to clear the ridge during the straight-line return home.
Mental exercise for every flight in complex terrain: trace the straight-line path back to your homepoint from wherever you might be when RTH triggers. Identify the highest obstacle or terrain feature along that path. Add 20-30m buffer above it. That is your RTH altitude. If you cannot do this exercise confidently for your planned flight area, fly conservatively and stay close to the homepoint rather than relying on RTH as a safety net over unknown terrain.
Regulatory consideration: FAA rules limit recreational drone flights to 400 feet (121.9m) AGL in uncontrolled airspace. Setting RTH altitude above 400 feet causes the drone to violate the altitude ceiling during an emergency return. The practical safe range for RTH altitude in uncontrolled US airspace is 80-120m AGL — high enough to clear most obstacles, safely below the 400-foot ceiling.
In controlled airspace (Class B, C, D, or E with surface extensions), your LAANC authorization specifies an approved altitude ceiling. Confirm your RTH altitude stays within the approved altitude for your authorization. A RTH event that causes the drone to climb above the LAANC authorization ceiling is still a regulatory violation even though it is an emergency. Fly conservatively enough that you avoid the airspace in the first place.
For the full explanation of how RTH works including homepoint setting, all three RTH triggers, and precision landing, see the guide on how drone Return to Home works.