▁air line ▁to ▁introduce ▁the ▁aircraft ▁into ▁service . ▁Since ▁the ▁A TR ▁ 7 2 ▁is ▁assemble d ▁on ▁the ▁same ▁production ▁line ▁as ▁the ▁smaller ▁A TR ▁ 4 2 , ▁along ▁with ▁sharing ▁the ▁majority ▁of ▁sub system s , ▁components , ▁and ▁manufact uring ▁techniques , ▁the ▁two ▁types ▁support ▁each ▁other ▁to ▁remain ▁in ▁production . ▁This ▁factor ▁may ▁have ▁been ▁cru cial ▁as , ▁by ▁ 2 0 1 5 , ▁the ▁A TR ▁ 4 2 ▁was ▁the ▁only ▁ 5 0 - se at ▁regional ▁aircraft ▁that ▁was ▁still ▁being ▁manufact ured . ▁ ▁During ▁ 2 0 0 0 , ▁the ▁combined ▁global ▁A TR ▁fleet ▁reached ▁its ▁ 1 0 , 0 0 0 , 0 0 0 th ▁flight , ▁during ▁which ▁a ▁distance ▁around ▁ 4 ▁billion ▁km ▁( 2 . 5 ▁billion ▁stat ute ▁miles ) ▁had ▁been ▁flow n ▁and ▁around ▁ 4 5 0 ▁million ▁passengers ▁had ▁flow n ▁on ▁board ▁A TR - built ▁aircraft . ▁The ▁ 2 0 0 7 ▁production ▁set ▁a ▁new ▁record ▁for ▁the ▁programme ' s ▁sales ; ▁a ▁total ▁of ▁ 1 1 3 ▁new ▁A TR ▁aircraft ▁had ▁been ▁ordered ▁during ▁a ▁single ▁year . ▁By ▁the ▁end ▁of ▁ 2 0 1 4 , ▁A TR ▁had ▁received ▁ 1 , 0 0 0 ▁orders ▁for ▁the ▁type ▁and ▁delivered ▁a ▁total ▁of ▁ 7 5 4 , ▁leaving ▁a ▁back log ▁of ▁ 2 4 6 ▁aircraft