[4] In 1982, Nilsson transferred to Linköping to become a test pilot at Defence Materiel Administration's Swedish Center for Experimental Research (Försökscentralen, FC) at Malmen Airbase.

He then completed the General Course at the Swedish Armed Forces Staff College from 1983 to 1984 and the young captain's success was rewarded with pilot training at the United States Naval Test Pilot School at the Naval Air Station Patuxent River in Maryland from 1984 to 1985,[1] where he finished first in his class.

[4] During his career, Nilsson has tested 35 different aircraft types, Swedish and foreign,[1] including, among others F-16 Fighting Falcon, F/A-18 Hornet and the Sukhoi Su-30.

[4] In early 2000, Nilsson served as head of the Planning Department of the Joint Operations Command (Operationsledningen, OPL) in the Swedish Armed Forces Headquarters in Stockholm.

[8] Nilsson was appointed First Marshal of the Court on 1 January 2012, in charge of planning the Swedish royal family's official program and representation.