I had a recent interesting behaviour when operating in a jungle situation near a waterfall in Malaysia. The waterfall was quite enclosed by steep rocks and overhead trees which meant that a GPS signal was almost impossible at ground level. I am reasonably experienced so decided to take off and fly in atti mode. Take off was fine but the spark would not go higher than about 3m. I assume this to be caused by the indoor height limitations. So how does the Spark decide it indoors? Thanks for any help