Wikipedia agrees with my perception...so I must be correct.
"A pejorative term for a person who lives at lower altitude, used by those living at higher altitudes."
The urban dictionary is more humerous (and less "G" rated so check out the link: (hope it works)
"http://www.urbandictionary.com/define.php?term=flat+lander"
(not really a link..you need to cut and paste...I hate technology)