MD-82
Human-Machine Interface
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
General None Reported / Taken
Human Factors
I loaded our flight plan into the GPS with a wrong fix; KA12Q vice KA21Q and missed the mistake. The 12Q fix is in the same general direction and is about the same distance. Maybe it would make sense to change the name of one of these fixes because it is very easy to transpose 12 and 21 while loading GPS and it is not an obvious mistake because of their proximity.This mistake will happen again if this change is not made.
An MD-82 pilot reported entering fix KA12Q vice KA21Q while entering the flight plan route in the GPS. Although unstated; it appears a track error resulted and was corrected by ATC.