| 25/08/1986 | N521US | roll out. |
| 14/11/1986 | N521US | first flight. |
| 01/12/1986 | N521US | del Northwest Airlines; '5521'; named "City of Denver". |
| 29/12/1986 | N521US | bt Potomac Capital Invetment Company; opb Northwest Airlines on lease. |
| 00/01/1987 | N521US | bt First National Bank of Boston, Boston, MA; opb Northwest Airlines on lease. |
| 04/02/1997 | N521US | bt State Street Bank & Trust Company, Boston, MA; opb Northwest Airlines on lease. |
| 12/02/2004 | N521US | bt Northwest Airlines Inc. |
| 13/02/2004 | N521US | rgd to Northwest Airlines Inc. |
| 00/03/2007 | N521US | at Las Vegas in 2003 Northwest Airlines c/s (repainted after 01/09/2006). |
| 29/10/2008 | N521US | Northwest Airlines merged into Delta Air Lines. |
| 19/06/2010 | N521US | at Boston in 2007 Delta Air Lines c/s with "Delta" titles (repainted after 17/05/2010). |
| 29/09/2014 | N521US | last service: Austin-Atlanta as DAL1308. |
| 01/10/2014 | N521US | ferried Atlanta-Marana as DAL9931 (TT: 86181 hours; 37648 cycles); for storage. |
| 28/03/2015 | N521US | at Marana; stored. |
