▁Rosen ▁worked ▁in ▁Eth iop ia ▁as ▁the ▁chief ▁instruct or ▁for ▁the ▁Imperial ▁Eth iop ian ▁Air ▁Force . ▁After wards ▁von ▁Rosen ▁was ▁employed ▁by ▁the ▁Swedish ▁char ter ▁air line ▁Trans air . ▁The ▁company ▁was ▁engaged ▁by ▁the ▁UN ▁during ▁the ▁Congo ▁Cris is ▁ 1 9 6 0 . ▁Von ▁Rosen ▁also ▁served ▁as ▁the ▁pilot ▁for ▁the ▁second ▁Secretary - General ▁of ▁the ▁United ▁Nations , ▁D ag ▁Ham mar sk jö ld . ▁However , ▁von ▁Rosen ▁was ▁ground ed ▁by ▁ill ness ▁when ▁Ham mar sk jö ld ▁was ▁killed ▁in ▁an ▁air ▁crash ▁while ▁medi ating ▁in ▁the ▁Congo ▁Cris is . ▁ ▁B ia fran ▁War ▁Von ▁Rosen ' s ▁invol vement ▁in ▁Africa ▁did ▁not ▁end ▁with ▁the ▁Congo ▁Cris is . ▁He ▁gained ▁international ▁fame ▁seven ▁years ▁later ▁when ▁he ▁fle w ▁relief ▁miss ions ▁for ▁aid ▁organis ations ▁into ▁war ▁torn ▁B ia fra , ▁a ▁break away ▁republic ▁of ▁Niger ia . ▁These ▁fl ights ▁included ▁flying ▁a ▁DC - 7 ▁from ▁São ▁Tom é ▁to ▁U li ▁at ▁only ▁a ▁little ▁above ▁sea ▁level ▁in ▁August ▁ 1 9 6 8 . ▁ ▁Dis g usted ▁at ▁the ▁suffering ▁the ▁Niger ian ▁government ▁inf lic ted ▁on ▁the ▁B ia fr ans ▁and ▁the ▁continuous ▁har ass ment ▁of ▁international ▁relief ▁fl ights ▁by ▁the ▁Niger ian ▁Air ▁Force , ▁he ▁h atch ed ▁a ▁plan ▁in ▁collaboration ▁with ▁the ▁French ▁secret ▁service ▁to ▁strike ▁back ▁at ▁Niger