wings and less on the top. this is the relative wind the steep of the angle of attack occurs the more likely you will get a stall. >> reporter: in the case of 8501 already a possible critical information, air traffic control data showing the a 320 ascending shortly before radar. >> it's disturbing to me an attempt was paid at least so far, we haven't verified it with data that he was avoiding weatherly going up. that's not something you'd rather like to do you like to go left to right. >> reporter: air france in 2009 was flying from rio to paris in a powerful storm. ice formed on the plane's exterior. the tubes deliver quickal information to the computers. pilots had confusing signals as to what was happening with the plane. >> they were getting horns, readouts on their displays