▁when ▁the ▁Engineering ▁Division ▁was ▁re ass igned ▁to ▁McC ook ▁Field , ▁near ▁dow nt own ▁Day ton . ▁McC ook ▁field ▁was ▁the ▁Army ▁Air ▁Service ' s ▁experimental ▁test ▁field . ▁There ▁Harris ▁was ▁appointed ▁Chief , ▁Fl ight ▁Test ▁Branch , ▁Engineering ▁Division , ▁US ▁Army ▁Air ▁Service . ▁At ▁McC ook ▁Field , ▁Harris ▁became ▁one ▁of ▁the ▁Army ' s ▁most ▁important ▁experimental ▁test ▁pil ots . ▁ ▁On ▁June ▁ 8 , ▁ 1 9 2 1 ▁Harris ▁became ▁the ▁first ▁pilot ▁to ▁fly ▁a ▁press ur ized ▁aircraft ▁when ▁he ▁successfully ▁fle w ▁a ▁Day ton - W right ▁US D - 9 A ▁with ▁an ▁experimental ▁press ur ized ▁co ck pit . ▁Two ▁McC ook ▁Field ▁test ▁pil ots ▁had ▁previously ▁tried ▁to ▁fly ▁the ▁aircraft ▁without ▁success , ▁including ▁test ▁pilot ▁John ▁A . ▁Mac ready , ▁who ▁held ▁the ▁world ▁alt itude ▁record ▁in ▁an ▁o xygen ▁equ ipped ▁un press ur ized ▁aircraft . ▁On ▁August ▁ 1 1 , ▁ 1 9 2 1 , ▁Harold ▁R . ▁Harris ▁fle w ▁the ▁first ▁air mail ▁aircraft ▁designed ▁to ▁pick ▁up ▁air mail ▁s acks ▁from ▁the ▁ground . ▁ ▁On ▁October ▁ 2 0 , ▁ 1 9 2 2 ▁Harris ▁made ▁history ▁as ▁the ▁first ▁pilot ▁to ▁b ail ▁out ▁of ▁a ▁str icken ▁aircraft ▁using ▁a ▁free - fall ▁par ach ute . ▁Harris ▁was ▁flying ▁a ▁Lo ening ▁mon op lane ▁with ▁a ▁modified ▁a iler