Pic must have been taken before 1991 as this example headed off to Northwest and later Delta.  Amazing to think this aircraft is over 48 years old: built in 1968.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/130275500@N02">G B_NZ</a>
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/130275500@N02/28642235795/">SAS DC-9-41 at LHR</a>