It's official: next release of INAV (1.8 or maybe 1.7.2) will incorporate an automated landing procedure for fixed wings. I was already writing about it 2 weeks ago, but now new code has been merged back and will be released.

Bear in mind, that this is not "state of the art" landing yet. It's rather a simple solution that can be used in emergency situations that will not crash an airplane, but rather put it on the ground without crashing. Procedure is quite simple:

  1. When Return-To-Home or Failsafe with RTH is engaged, go to Home position
  2. When Home is reached, start to loiter with defined radius and descend. Descent speed is limited to nav_landing_speed when altitude is above nav_land_slowdown_maxalt. When altitude is below nav_land_slowdown_maxalt, vertical speed is scaled down to one fourth of nav_landing_speed at nav_land_slowdown_minalt. So, on using default values, vertical speed is between 2m/s and 0.5m/s
  3. During descend, airplane is not allowed to raise throttle above nav_fw_cruise_thr when nose is up. This is to prevent airplane from gaining horizontal speed
  4. When nav_land_slowdown_minalt is reached, ROLL axis is locked to 0 degrees, PITCH axis is locked to nav_fw_land_dive_angle (default is 2 degrees) and motor is stopped when MOTOR_STOP is used or put to IDLE when MOTOR_STOP is not used. This puts airplane into a shallow dive to the ground

fixed wing landing in inav

That is all. Airplane should glide last few meters to the ground. Most designs should be able to do it without a problem. My testing platform did it like that:

Since there is no auto-disarm procedure yet, MOTOR_STOP is recommended to prevent propeller from breaking and motors/ESC from burning.