The FAA height waiver allows the park to build a structure as tall as 355 feet.
Iron Gwazi will be the world's fastest and steepest hybrid coaster when it opens in 2021.
SeaWorld will now be open Thursdays through Sept. 6.
The hard-ticket event will open only part of the park and six rides, including three coasters.
Busch Gardens Williamsburg is one of three SeaWorld-owned parks that remain closed.
Two Epcot area resorts are now set to remain closed until further notice.
On Feb. 15, Electric Umbrella and Pin Central at Epcot will close, followed by Agent P's World Showcase Adventure on Feb. 17.
The festival runs on Fridays, Saturdays, and Sundays from February 7 through May 5, but the concerts are limited to weekend evenings at the park’s Bayside Stadium starting at 6 p.m.
SeaWorld reported its first year-over-year drop in quarterly attendance since 2017, which the company blamed on Hurricane Dorian and bad weather.