"Hi, I flew my multicopter about 50m under the home altitude. You need to change in the FLIGHT PLAN tab the "Alt Warn" value to -500 for example, then you are able to fly up to this relative altitude.
Best Regards,
Luis"

"Hi Christopher,
I have a few question...if you can help me:

1.- Which version of Piksi did you use? "Piski multi" or only "Piksi"
2.- How accurate is it? many say centimeter accurate, but 1cm - 10cm - 50 cm aprox?
3.- How much time does it take to…"