A rally point is required, and none is close enough

What ArduPilot says:

• PreArm: Can't check rally without position
• PreArm: No sufficiently close rally point located
• PreArm: No rally library present

ARMING_MIS_ITEMS bit 5 demands a rally point (a place other than home that RTL may return to) near the aircraft. ArduPilot takes the nearest stored rally point. If none is stored, or RALLY_LIMIT_KM is above 0 and the nearest one is farther away than that, arming is refused. RALLY_LIMIT_KM is 0.3 km by default on Copter and 5 km on Plane. “Can't check rally without position” means there is no position yet to measure from. “No rally library present” means this firmware was built without rally points.

What to do, most likely first

1. No rally points are stored on the aircraft.

   CheckRALLY_TOTAL is 0, and reading the rally points in the ground station returns nothing.

   FixPlace a rally point in the ground station's Plan screen where a landing is safe, and write the rally points to the aircraft.

2. The stored rally points belong to another field: the nearest is farther than RALLY_LIMIT_KM.

   CheckRead the rally points back and measure on the map from the aircraft to the nearest one.

   FixPlace rally points for this field and upload them. Leave RALLY_LIMIT_KM alone: it is what stops a rally point left over from another field being used.

3. There is no GPS position yet, so the distance cannot be measured.

   FixWait for the GPS fix; the message then changes or goes away.

Parameters to look at

Where to do it:Mission Energy Check