Timely: *Flying* Magazine, Feb. 2014
From Peter Garrison's *Flying* Magazine article, "A Violent Sky," p. 24, relating to a small aircraft (U.S. Utility category), but applicable in principle to Transport category aircraft as well:
"...Strength requirements for certification [of this category] are based on a 50 foot per second vertical gust. The effect of such a gust is both to increase the indicated airspeed slightly and, more important, to change the wing's angle of attack. An airplane moving horizontally at a true 170 knots would experience an effective increase in angle of attack of about 10 degrees. This would be equivalent to a 4.7 G pull-up--enough to wrinkle [the aircraft]..."