GRAND FORKS - University of North Dakota pilots will be allowed to use their "Sioux" call sign when communicating with air traffic control towers nationwide, the Federal Aviation Administration says.

The FAA's decision is a reversal from last week, when the agency told the university it could no longer use the call sign outside of local air space, about a 40-mile radius around the university's flight school.

Elizabeth Isham Cory, a spokeswoman with the FAA's Great Lakes Region, said it was a safety issue and was not related UND's long debate over its Fighting Sioux nickname for athletic teams.

"There was a question at another FAA facility whether the (Sioux) call sign might be a bit of a tongue twister," Cory said. "Somebody heard 'Sioux' and thought it was 'two.'"

Cory said a survey then was conducted within the FAA and with pilots, and Sioux won out over the "November-Delta" call sign, signaling "North Dakota" aircraft.

Cory said the FAA now is encouraging UND pilots to use the Sioux call sign as much as possible so there is no confusion.