Regional Jet 200 ER/LR (CRJ200)
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Procedure
Handed off to Departure Control. Departure cleared us to 10;000 feet and 'ON COURSE TO CTF.' The [previous 060] heading had taken us east of the 'on course' line from ZZZ to CTF so the First Officer and I agreed that ON COURSE; is not direct and we needed to come left a few degrees to intercept the on course route. We both agreed that on course and not direct was the clearance. After a minute or so the Departure Controller asked if we were direct CTF. I stated no we were joining the on course route. He turned us to 90 degrees for a minute and then cleared us 'ON COURSE DIRECT TO CTF.' He asked if we misunderstood his previous clearance and when I tried to explain the difference between ON COURSE; and DIRECT he did not agree and did not seem to understand that there is a difference. I do not know of any changes to those clearances and would certainly like to know if they have changed.
CRJ200 flight crew track deviation due to interpreting 'on course' to a VOR differently than Controller who believed it to mean the same thing as 'direct' to the VOR.