Ruben Mitchell, of Stockton, Calif., was sentenced Monday by a federal judge in Pittsburgh.
Defense attorney William Kaczynski argued for a lesser sentence, saying Mitchell, 45, quit the drug business after he lost the bag on a Pittsburgh-bound flight in February 2009.
But Assistant U.S. Attorney Ross Lenhardt told the sentencing judge Mitchell "didn't quit, he was fired."
Investigators said a flight attendant put the bag in the plane's cargo hold because it wouldn't fit in an overhead luggage compartment.
The bag was then mistakenly unloaded during a layover in Las Vegas, where the drugs were found.