[填空题]
A pilot performs an evasive maneuver by dividrw e.gf;rbi-1iv*i 6ng vertically at 310c4uy 1*xbl g2v $\mathrm{~m} / \mathrm{s}$ . If he can withstand an acceleration of 9.0 g 's without blacking out, at what altitude must he begin to pull out of the dive to avoid crashing into the sea?
