Setting Up Return-to-Home (RTH) Mode

I. Principle

Return-to-Home (RTH) mode is used to bring the aircraft back to the takeoff position, or return to the safe takeoff point if the SafeHome feature is enabled. By default, the takeoff position is where the aircraft was first unlocked. RTH simultaneously controls the aircraft's position and altitude. If the aircraft does not have an altitude sensor (such as a barometer), altitude needs to be manually controlled.
Under default settings, if the aircraft is less than 5 meters from the takeoff position, RTH will immediately land; if further away, the aircraft will ensure it reaches at least 10 meters in altitude. Fixed-wing aircraft will fly home at cruise throttle and will circle or land according to settings. Multirotor aircraft will begin returning home at 3 meters/second and will eventually land. If auto-unlock is configured, the aircraft will automatically unlock after landing; if not configured, manual unlocking is required after landing.
Return-to-Home (RTH) mode is activated through the RTH Control in flight modes, applicable to both multirotor and fixed-wing aircraft, with the only difference being how the aircraft climbs or descends during circling.

II. Basic Settings

Important

You can refer to the following parameters for quick setup:

3. Specific Details

3.1 RTH Altitude

RTH altitude mode has two altitude-related settings: RTH altitude and RTH Home altitude.

• RTH altitude determines the altitude at which the aircraft returns home. This setting determines the minimum altitude the aircraft will maintain during the return process.
• RTH Home altitude sets the hover altitude when the aircraft reaches the takeoff point. If the aircraft arrives at an altitude higher than RTH Home altitude, it will begin descending in a spiral pattern until reaching the set RTH altitude. The default value is 0, which means this feature is disabled. In this case, if linear descent is enabled, the aircraft will hover at the RTH altitude.
  These two settings work together to precisely control the aircraft's altitude and hovering behavior during RTH.

3.2 RTH Altitude Control Mode

RTH can control altitude in several different ways, which are controlled by the RTH altitude mode and RTH altitude parameters (altitude in centimeters).

3.2.1 Hold Current Altitude

• RTH altitude mode set to CURRENT
• RTH altitude - No setting required
  The altitude before return is the altitude at which the aircraft returns home, ignoring any RTH altitude settings.
  

3.2.2 Hold Current Altitude and Add Defined Safety Altitude

• RTH altitude mode set to EXTRA
• RTH altitude - Define the required additional altitude
  The altitude before return is the aircraft's current flight altitude plus the RTH altitude.
  

3.2.3 Predefined Altitude

• RTH altitude mode set to FIXED
• RTH altitude - Define the exact return altitude above the return point
  If the aircraft is below the RTH altitude, it will climb to the required altitude before returning home. If the aircraft is above the required altitude, it will descend during the return.
  

3.2.4 Maximum Altitude Since Takeoff

• RTH altitude mode set to MAX
  INAV versions before 4.1:
• RTH altitude - Define the exact return altitude above the return point
  INAV versions 4.1 and above:
  The aircraft will return home at the maximum altitude reached since takeoff. If the aircraft has not exceeded the RTH altitude value during flight, it will return at the RTH altitude. If RTH altitude = 0, this feature is disabled.
  

3.2.5 Predefined Altitude at Least Above Takeoff Point

• RTH altitude mode set to AT_LEAST
• RTH altitude - Define the minimum altitude above the takeoff point during return.
  

3.2.6 Predefined Altitude with Linear Descent

For INAV versions before 7.0:

• RTH altitude mode set to AT_LEAST_LINEAR_DESCENT
• RTH altitude - Define the minimum altitude above the takeoff point during return.
  If the aircraft is below the RTH altitude, it will climb to the required altitude before returning home. If the aircraft is above the required altitude, it will gradually descend (along a linear straight line) while turning to return home. This defines the actual RTH return altitude. The aircraft will descend in such a way that it reaches exactly the RTH altitude when arriving at the return point. Therefore, the aircraft can save energy by descending gently during the return journey.
  

3.3 Linear Descent

For INAV versions 7.0 and above
Before INAV 7.0, linear descent was an extension of the AT_LEAST mode. Starting from INAV 7.0, linear descent can be used with all RTH return modes and has been expanded to provide more pilot control options.
Since all RTH return modes can now use linear descent, a target descent height applicable to all RTH modes is needed. For this purpose, the target altitude for linear descent is now RTH Home altitude. This parameter must be set for the linear descent feature to work.

3.3.1 Warning for RTH Return Altitude Below 10m

If Linear Descent is enabled and RTH Home altitude is less than 10 meters, a warning will be displayed around the RTH return altitude input field. You can still enter any value (including 0), but you need to ensure this value is safe in your flying environment. If RTH Home altitude is not set, the linear descent feature will not be used during flight**.

3.3.2 Linear Descent Start Distance

An option has also been added to set the starting distance for linear descent, which is controlled by the Linear Descent Start Distance parameter.

• Default value is 0 (maintain current behavior). When this value is set to 0, linear descent begins immediately after entering RTH return mode.
• You can also specify a distance from the return point (in meters, up to a maximum of 10,000m, i.e., 10km), at which the aircraft will begin linear descent.
• In all cases, the goal of linear descent is to descend to RTH Home altitude when reaching the return point (if possible).
  

Important

Although this feature is still called Linear Descent, in some cases (such as when the flight altitude is below the takeoff point), it may behave as Linear Ascent, meaning the aircraft will climb to RTH Home altitude.

**3.4

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