How will RTL react if copter armed before getting GPS lock

So I know if you have a GPS lock, the home position gets stored when the flight controller gets armed, but what if you arm and take off in a non-GPS flight mode before you get a GPS lock? Will it store the home position once it gets a GPS lock while in the air? Or does it always store the home position when you arm, even if you only have 4 satellites and an HDOP of 40? Or will it not store any home position?

I was just curious if you were to take off before having a GPS lock, would an RTL command be ignored, would it land instead of RTL (even if it has good GPS currently while in air), or would it try to RTL to some home position that might be 1000 meters away?

Thanks for helping me understand how this works a little better!

I posted this same question in the Arducopter group on DIYDrones. Randy responded with the following:


It stores the home position when it first get GPS lock and also whenever the vehicle is armed so as you suspect if you take-off without a GPS lock, it will record the home position (used for RTL) when it does finally get the lock.  It does this regardless of the HDOP so it's possible for that position to be off from the vehicle's actual position.  To close this loophole in future versions we will probably introduce the idea of an "Indoor mode" and an "outdoor mode" and if you arm without a GPS the vehicle will go into "indoor mode" and RTL and all other autonomous features will be disabled until the pilot lands and re-arms.  We need to make sure that it's obvious to the pilot which mode the vehicle is in and make sure we make things better instead of worse (in terms of safety and useability) so we still have some more thinking to do.

Here is a link to the post if you want to see all the replys: … g-gps-lock