The aircraft with manufacturer serial number 21508 and line number 518 is a Boeing 737-291. It had its maiden flight on 1978-04-27. The last recordered registration was N977UA. The airframe is scrapped.
History:
Frontier Airlines, from 12th of May 1978, registered as N7391F United Airlines returned, from October 1985, registered as N977UA Sky King, from 16th of October 2003