Return-to-Home sounds like a single command: climb, fly back and land. In practice, the path depends on the aircraft, its distance from the Home Point, the selected RTH mode, the quality of satellite positioning and whether the vision system can see well enough to help.

That makes the RTH altitude an important pre-flight setting, but not a universal safety ceiling. A number entered in the app cannot inspect a crane that arrived this morning, a ridge hidden behind the take-off point or a cable that the obstacle sensors may never detect.

The aircraft may not use the number in the way you expect

DJI’s current RTH guidance distinguishes between Optimal, Preset and straight-line behaviour on supported aircraft. Under Preset RTH, an aircraft more than 50 metres from the Home Point may ascend to the configured RTH altitude if it is flying lower. At shorter distances, some models return at their current altitude or land immediately. If the aircraft is already above the configured altitude, it may stay at its current height rather than descend first.

Advanced systems can plan a route around obstacles when lighting and the environment suit the vision system. When they do not, the aircraft may switch to a more direct return. Product families also use different distance thresholds and sensor combinations. The correct logic is therefore the logic in the manual for the exact aircraft and firmware you are flying—not a rule remembered from another drone.

Height is measured from the recorded Home Point

The displayed RTH altitude is normally referenced to the recorded Home Point, not to every piece of terrain along the route. If the drone launches in a valley and flies toward rising ground, a setting that clears the trees beside the pilot may not clear the slope farther away. Moving between different elevations makes this easy to overlook.

Before take-off, confirm that the Home Point has been recorded where you expect. Then look at the whole likely return corridor: terrain, buildings, masts, cranes and other obstacles. Set a height that gives appropriate clearance while remaining within the applicable operating limits. If the route or legal ceiling makes that impossible, change the flight plan rather than treating a larger app number as the solution.

Obstacle sensing does not remove the planning job

DJI warns that insufficient light can prevent vision systems from avoiding obstacles during RTH. Thin branches, wires, reflective surfaces and obstacles outside the sensing directions can also remain difficult. Strong wind, weak GNSS and GEO restrictions may change what the aircraft can do on the way home.

A useful pre-flight check is short:

• Confirm the Home Point and the signal-loss action.
• Read the exact model’s RTH distance thresholds and sensor limits.
• Inspect the likely route, not just the space above the launch pad.
• Choose an altitude that clears known obstacles without exceeding the flight’s legal or operational limit.
• Keep enough battery and wind margin to return without relying on a last-minute automated recovery.

RTH is a recovery aid, not a substitute for knowing where the aircraft is and what lies between it and home. The safest setting is the one matched to the actual route, aircraft and conditions before the propellers start.

Sources

• DJI Support: Drone RTH Logic
• DJI Support: Flight Safety Guidelines

Editorial note: RTH behaviour varies by aircraft, firmware and operating conditions. This article explains planning principles from manufacturer guidance and is not a flight test of a particular model.