"He was found guilty on the two charges...and ordered to pay R5 000 or spend 10 months in jail," Guy Leitch said.
Swift, 52, was arrested at OR Tambo International Airport in February last year after officials saw him taking photos of landing planes.
He was found with a radio receiver that cannot transmit but is still illegal without a radio license under the Regulation of Interception of Communications and Provision of Communication-Related Information Act.
The Independent Communications Authority of SA requires an operator of a receiver to qualify as a radio amateur.
Leitch said air traffic communications were easily accessible via internet live-streaming or at the High Flyers Bar at the end of OR Tambo's airstrip.
Swift, therefore, was accessing information which was freely available and should never have been charged.
Planespotting is the observation and logging of an aircraft's registration numbers as a hobby. In many countries, planespotters co-operate with police in reporting anything suspicious as a measure to target terrorism.