Over time, users may encounter pre-arm errors that will prevent takeoff. Usually the user will take note of pre-arm errors in the bottom center of the screen, displayed with a yellow dialog box. The user can also view a log of errors via the megaphone icon on the icon bar at the top of the screen. The icon has two states: no alerts and unread alerts. No alerts will be displayed as a megaphone icon, and unread alerts will display as a triangular warning icon.
Below a list of pre-arm errors that the user may encounter during general operations has been compiled, along with actions the user can take to resolve them.
No GPS Lock - Check the number of satellites you’re receiving, which can be done by viewing the number next to the satellite icon on the icon bar at the top of WISPR Ground Control. If there are less than 13, reboot the drone. If that doesn’t clear the error, try moving the drone to a different location- ideally wherever offers the maximum clearance between the GPS and the sky. Obstructions can have a significant impact on satellite detection. You will know you have achieved GPS lock when the LED lights on the sides of the GPS are blinking green and continue to do so.
GPS High HDOP - This triggers based off of a function that measures position accuracy, and can appear in flight modes where GPS is necessary. Allow a small amount of time to elapse in order for the GPS to settle, as sometimes this error can clear itself without need for action. If the error persists, try either rebooting the drone, or moving the drone to different location especially away from metal objects. Even rebar directly underneath concrete the drone is resting on could potentially trigger this.
GPS Glitch - This occurs when the GPS is not reading the correct coordinates for more than 5 seconds. This usually will resolve itself by waiting for the number of satellites to increase. If it doesn’t clear on its own, move the drone to a different location, paying heed to metal nearby. A reboot can potentially solve this as well if you seem to be unable to find ideal positioning. If the error persists, the GPS needs to be inspected- and likely recalibrated.
Need 3D Fix - This error occurs when the drone is in a mode where it requires a GPS signal to take off, but the GPS signal isn’t strong enough. It is handled in much the same way as the GPS Glitch and High HDOP errors, as they are all GPS centric. This can almost always be solved by moving the drone a few feet over from its current position. A common cause of this is the presence of metal in the ground beneath where the drone rests. If that does not fix it, a simple reboot should fix it. If neither of these work, it may be time to look at the GPS for hardware issues.
Battery Below Arming Voltage - You will receive this error if the drone detects the voltage output of the currently equipped battery is too low. This occurs to prevent beginning a flight with a battery that may deplete too quickly and result in a crash. Charge the battery completely before flying, or swap to a fresh battery.
Pre-Arm: Waiting for Terrain Data -
Check that you have the terrain data tiles downloaded for the area you are flying.
When downloading maps, be sure to have the “terrain data” option checked to ensure that terrain data is download alongside the map you download. If the download of the terrain data is unsuccessful, or if you have terrain data but are still encountering this error and subsequently are unable to take off, then you may disable the “Enable terrain follow during RTL and Land” in WISPR General Settings. Simply uncheck this box to fix the pre-arm warning. Keep in mind this will not use terrain data when you RTL or while landing.
For a guide with information relevant to this error, check out this link:
Downloading Maps While Offline and Setting Terrain Follow
Pre-Arm: Check Proximity Sensor - There may be an object too close to the sensor, or the sensor may be malfunctioning. Generally the best practice is moving the drone to a spot where it is less likely to pick up anything that will cause the pre-arm, but sometimes this issue won’t resolve itself until a reboot occurs. Occasionally, allowing some time to elapse will let the sensor recognize a falsely detected obstruction, and it will clear the error. Try these approaches multiple times. If the sensor continues displaying the error, the option to disable it exists in the general tab of the WISPR Ground Control settings. You can find this by tapping the WISPR logo in the top left corner of WISPR Ground Control.
If you opt to do this, please exercise extreme caution when flying. With this setting disabled, the drone has no collision avoidance active and nothing will prevent the drone from flying directly into an obstacle or bystander.
Compasses Inconsistent - This is caused from reading the Internal and External compasses as pointing in different directions. Reboot the drone. If the same pre-arm error continually appears, a compass calibration should fix this.
Pre-Arm: ESC Temp Over Threshold. False Reading Detected - This error occurs when temperatures are very cold. The values for the ESC temps range from 0-255 degrees Celsius. When the value is read as below 0 from the cold, it will cause a false reading that registers the ESC temps as maximum. This error appearing just confirms the drone has detected the false reading. Do not be alarmed by this error, as it will not alter the drone’s behavior and should have no impact on pending operations. If you see this, you may safely close the message box and continue.
Low Battery Failsafe RTL - This means the drones has calculated how far it is from home and how much battery it will take to get back to home safely. This sequence should never be cancelled unless in an emergency, in which case the drone should be landed immediately.