The lift motors are carrying the aircraft while it gains airspeed

What ArduPilot says:

• Transition started airspeed N.N
• Transition airspeed wait

A transition is the change from hovering on the lift motors to flying on the wing. In its first stage the lift motors hold the aircraft up while the forward motor speeds it up to AIRSPEED_MIN. “Transition started airspeed X” is sent when assistance switched the lift motors on, usually because the airspeed X is below Q_ASSIST_SPEED; “Transition airspeed wait” when no assistance applies. Normal after leaving a Q mode. In the middle of a fixed-wing flight the same line means the lift motors came back on: speed assistance has no message of its own.

What to do, most likely first

1. In cruise: the airspeed dropped below Q_ASSIST_SPEED, in a slow turn, a steep climb or a gust from behind.

   CheckThe number in the message is the airspeed at that moment; compare it with Q_ASSIST_SPEED and with the speed you meant to fly.

   FixIf the aircraft really slowed that much, find out why: too little throttle, too steep a climb. If it was flying normally, Q_ASSIST_SPEED is too close to the speed you fly: keep it about 3 m/s under AIRSPEED_MIN.

2. The airspeed sensor reads too low: a blocked or leaking tube, or a sensor that was never calibrated.

   CheckIn the log, compare airspeed with ground speed: in calm air they should be close. Lift motors that run through the whole flight point to this.

   FixRepair the tubing and calibrate the sensor before the next flight.

3. There is no airspeed sensor, and the airspeed ArduPilot estimates from GPS and wind is off in gusts and turns.

   FixFit an airspeed sensor, or set Q_OPTIONS bit 12: speed assistance is then ignored whenever the airspeed is only an estimate, while altitude and angle assistance keep working.

Parameters to look at