Dash 8-200
Communication Breakdown; Training / Qualification
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Airspace Structure; Human Factors
ACR X was bound for Middleton (Harrisburg Int'l).  About 10 minutes later he asked for FL180 for a final; and I then issued it as his final.  He then asked for 'direct to the field'.  I paused and issued the pilot 'direct to Harrisburg'; then entered direct Harrisburg (HAR) in the computer. The Pilot read back 'direct Harrisburg'; and that was the end of it.  Later the Operations manager and my supervisor advised me that a controller in area 5 ( who works the Harrisburg airspace noticed that the aircraft was slightly off course; and asked the pilot if he was direct Harrisburg VOR; or Harrisburg Airport. The pilot said 'airport'.  The controller then turned the incident in to his supervisor; because (HAR was in the computer; not KMDT) the airport identifier.  The issue is: When I issued the pilot 'direct Harrisburg' (HAR); my intent was exactly that; to send the pilot to Harrisburg VOR.  I never said 'Harrisburg Airport'.  The pilot took the clearance as Harrisburg airport; and went direct to MDT.  His readback was 'direct Harrisburg'; not 'direct Harrisburg airport'.  Which would have prompted me correct him.  To my knowledge there were no other airspace violations or loss of separation as a result of this.  Management made me aware of the situation because I never realized I did anything incorrectly.  My knowledge of the rules was that if I wanted to send an aircraft to the airport; I specified 'airport'. Airports and their corresponding VORs should not have the same name.  This adds confusion between the pilots and controllers. I am aware this is an ongoing problem; that is happening regularly.  Pilots and controller should be on the same page.  If the intent is to send the aircraft to the airport; than 'airport should have to be stated and read-back.
ZOB Controller reported being surprised when a clearance 'direct Harrisburg' resulted in the aircraft proceeding to the airport instead of the VOR.