Hi this was my first time making a quadcopter and unfortunately it crashed,.
It flew just fine for few days but this time, when I changed mode to RTL, It crashed.
Log attached
also what’s the unit of alt? (m or cm)
Hi there, welcome to the community.
There are many reasons that can cause a crash. But before we answer you, please do answer one question: why are you not using ArduCopter 4.5.7 ?
Well, that error is not solvable by fw update. But is avoidable by correct configuration of all relevant parameters. 
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