747-400 United Airlines747 400 United Airlines airplane model. Experience the unparalleled innovation of the 747 400, released by Boeing in October 1985. After its first development flight on April 29, 1988, the aircraft was quickly awarded US certification in January of the following year. While externally similar to the 300, the 747 400 boasts significant improvements including a new, state of the art digital flight deck with six large CRT displays, winglets for enhanced