The 60-year-old man, David Alan Anderson, will be sentenced Tuesday in U.S. District Court in Salt Lake City.
Anderson pleaded guilty in January to possessing a dangerous weapon - a charge punishable by $250,000 in fines and up to 10 years in prison.
Prosecutors are dropping a second charge accusing Anderson of threatening police and FBI agents who pulled him off the plane for questioning.
Anderson was removed Sept. 18 from a Delta Air Lines flight to Las Vegas. Authorities said he threatened to slit his seatmate's throat in a dispute over a shared armrest.
Anderson was held in jail for a month and then released.
(Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)