User guide

23 Free flight
If the problem persists, it may be necessary to replace the mother
board.
Alert messages
Note: Alert messages are simple warnings. They do not stop you controlling the AR.Drone.
Message
Explanation/Correction
VISION ALERT
The vertical camera cannot carry out a speed measurement.
This problem can occur at low lighting levels.
Note: The AR.Drone may drift horizontally without any action on your part.
Fly the AR.Drone at a height between 1 and 6m.
Use the AR.Drone in better lighting conditions.
ULTRASOUND
ALERT
The altitude measurement is not available.
The ultrasound signals are disturbed.
The device may fly too high or too low.
Note: The AR.Drone may climb or drop without any action on your part.
Fly the AR.Drone at a height between 1 and 6m.
Check that the altimeter is not obstructed (leaves, dust, etc.).
If the problem persists, it may be necessary to replace the navigation
card.
BATTERY LOW
ALERT
The battery is nearly discharged.
Note: When the battery is discharged, the AR.Drone lands automatically.
Change or recharge the battery of the AR.Drone.
Emergency messages
Note: Flying is not possible with an emergency message on the screen.
Message
Explanation/Correction