An unruly Delta Airlines passenger who tried to open an emergency exit door, fought with a flight attendant midair and forced an emergency landing was ordered to spend 18 months behind bars. Mario Nikprelaj, 24, was sentenced Tuesday after pleading guilty to one count of interfering with flight crew members and attendants during a SkyWest flight from Nebraska to Detroit, Mich. last July, the US Attorney’s Office for the Northern District of Iowa announced. Nikprelaj, a Shelby Township, Mich. native, must also serve a two-year term of supervised release after completing his prison sentence.