2 9 ▁March ▁the ▁I AC ▁announced ▁that ▁pre lim inary ▁analysis ▁of ▁information ▁from ▁the ▁flight ▁record ers ▁showed ▁no ▁fail ures ▁of ▁any ▁aircraft ▁systems , ▁engines ▁or ▁other ▁components ▁had ▁been ▁discovered ▁to ▁date . ▁The ▁air worth iness ▁certificate ▁was ▁valid , ▁all ▁necessary ▁maintenance ▁history ▁was ▁in ▁good ▁order ▁at ▁the ▁time ▁of ▁departure . ▁A ▁trans cript ▁of ▁more ▁than ▁two ▁hours ▁of ▁the ▁last ▁crew ▁communic ations ▁was ▁prepared ▁but ▁was ▁not ▁released ▁to ▁the ▁press ▁as ▁international ▁and ▁Russian ▁rules ▁of ▁air ▁crash ▁investigation ▁forb id ▁publication . ▁The ▁I AC ▁requested ▁Bo eing ▁provide ▁technical ▁documentation ▁to ▁aid ▁in ▁assess ment ▁of ▁the ▁aircraft ' s ▁system ▁operations ▁and ▁about ▁all ▁similar ▁previous ▁inc idents ▁with ▁Bo eing ▁air frames . ▁ ▁In ▁August ▁ 2 0 1 8 , ▁the ▁I AC ▁began ▁re construct ing ▁data ▁from ▁the ▁head - up ▁display ▁( H UD ) ▁system . ▁ ▁On ▁ 2 6 ▁November ▁ 2 0 1 9 , ▁the ▁I AC ▁released ▁their ▁final ▁report ▁of ▁the ▁crash . ▁ ▁Pre lim inary ▁find ings ▁▁ ▁On ▁ 2 0 ▁April ▁ 2 0 1 6 , ▁a ▁first ▁inter im ▁report ▁was ▁published ▁by ▁the ▁I AC . ▁Find ings : ▁▁ ▁Both ▁approaches ▁were ▁conducted ▁in ▁flight ▁director ▁mode , ▁with ▁the ▁aut op il ot ▁and ▁aut oth rott les ▁dis eng aged . ▁There ▁were ▁no ▁significant ▁heading ▁or ▁alt itude ▁devi ations ▁from ▁the ▁pres