Echo 051 was a UNSC Pelican dropship in service in late 2552, during the final battles of the Human-Covenant War.
That year, the Pelican was used during the Second Battle of Earth, and the Second Battle of New Mombasa. There, Echo 051 and another unknown Pelican were sent to retrieve the Master Chief and the Arbiter as well as Sergeant Major Avery Johnson and several Marines. Unfortunately, the two Pelicans were ambushed by Covenant Banshees and Phantoms piloted by the Brutes. Echo 051 was able to maneuver away from the fire, even though it took a direct hit on its front right engine as it was loading soldiers, spinning out of control and crashing upside down near a cliff where its survivors, including Sergeant Johnson, were captured by the Brutes. Its unknown wingman spun in the same direction but crashed in the river, sinking to the bottom. Though, this is just speculation.
Kilo 023 was later sent to retrieve the survivors of the crash of Echo 051, Master Chief, and the Arbiter. [1].
References
- It is in halo 3 the first lvl.