Complex sentence: Having witnessed a plane crash in 1912, Banič constructed a prototype of a parachute in 1913 and tested it in Washington, D.C. before U.S. Patent Office and military representatives, jumping first from a 15-storey building and subsequently from an airplane in 1914.
Split into simpler sentences: Having witnessed a plane crash in 1912, Banič constructed a prototype of a parachute in 1913. It is claimed that he tested it in Washington, D.C. jumping first from a 15-storey building and subsequently from an airplane in 1914.