From Halopedia, the Halo wiki
During the Battle for Arcadia, Cargo 3, alongside Cargo 1 and Cargo 2, was used to transport civilians away from Arcadia. The male pilot requested help after being attacked by Covenant forces. After being attacked several times during the battle, the pilot went AWOL and disobeyed orders by trying to leave the planet without rescuing the incoming civilians. The transport was destroyed by Covenant Type-26 Banshees as it attempted to take off and all inside, as well as the civilians nearby, perished.
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