6 Echo 6 (Earth-2042)

6 Echo 2 was a civilian freighter. It, along with other transports, was used to evacuate both soldiers and civilians from New Harmony during the Fall of Reach.

During the evacuation, it was ordered not to take off due to heavy enemy fire. However, the pilot disregarded instructions and took off anyway, which resulted in the destruction of the ship and the death of everyone on board. Clone trooper personnel considered the deployment of search-and-rescue teams, but the situation was quickly written off as hopeless as the vessel sank into the bay.

Source

 * https://www.halopedia.org/6_Echo_2