VTOL Approach Speedweight is Causing Stall

Hi, I have a problem with the speedweight during approach (AP 4.3.3).

  1. Before 11:39, aircraft is loitering to final altitude before approach and land
  2. Right at 11:39 entering VTOLLAND, with VTOL Approach distance of 200m
  • Target airspeed was dropped by 10% to 15.75 from 17.5 ( I am not sure why, but this one is still fine)
  • TECS.w was dropped to 0 !!
  • Altitude is dropped a bit due to decrease in airspeed and I think because of the momentum when descending
  • due to 0 speedweight, aircraft is trying hard to pitch up to compensate for altitude loss.
  1. at 11:46 desired pitch reached maximum, and airspeed was already slightly below fbw_min (14 m/s) and then aircraft stall, then stall prevention was triggered to recover aircraft.
  2. 11:48 aircraft regained speed again and perform approach then land.


  • Current fix for me is to limit the sink and also by limiting the TECS pitch max and min,
  • I tried to change the TECS_LAND_SPDWGT as well, however this parameter has no effect to this condition.
  • It seems that the aircraft changed the flight mode to VTOL, thus disregarding any TECS speed weight,

Is there any parameter that I should change to increase the speedweight during the approach ?

I think it should enter VTOL state with lift motors running before stall. Maybe take a look at transition tuning.