throughout the summer of 1911,cooke practiced in the black diamond several times a day and made his exhibition flying debut at the walnut creek grape festival on october 6,7 1911. on 19 december 1911 cooke was the first person to overfly mount tamalpais in marin county, california in the black diamond. the flight ended in mill valley, california in-route to oakland after an engine failure and glide to landing from 2000 ft of altitude.