The last waypoint is too close to the VTOL landing point

What ArduPilot says:

• PreArm: VTOL land too short, min N.Nm

In the mission, a landing item comes straight after a waypoint that is too near to it. The aircraft passes that waypoint at wing speed and needs room to slow to a hover: speed squared divided by twice Q_TRANS_DECEL. ArduPilot wants at least 0.75 of that between the two points and prints the figure. The speed is TECS_LAND_ARSPD when it is above 0, AIRSPEED_CRUISE otherwise: at 18 m/s and the default 2 m/s² that is 61 m.

What to do, most likely first

1. The waypoint before the landing is nearer than the distance in the message.

   CheckMeasure the last leg in the mission planner.

   FixMove that waypoint away from the landing point, to at least the distance in the message; put it downwind, so that the aircraft brakes into the wind.

2. TECS_LAND_ARSPD is not set, so the distance is worked out from the cruise speed.

   CheckWith TECS_LAND_ARSPD at -1 the approach itself is flown halfway between AIRSPEED_MIN and AIRSPEED_CRUISE, but this check takes the full AIRSPEED_CRUISE.

   FixSet TECS_LAND_ARSPD to the speed you want on the approach, safely above the stall: a slower approach needs less room.

The check looks at every landing item that follows a plain waypoint: VTOL_LAND, NAV_LAND and payload place, even a NAV_LAND that Q_OPTIONS bit 2 makes a fixed-wing landing.

Parameters to look at

Where to do it:Mission Energy Check