Narrative:

At approximately XA50, upon handoff from den departure control to ZDV, request was made for clearance direct slurb intersection. Center requested that flight temporarily continue as filed for traffic sep. At approximately XB00 clearance was received for an approach to the avon stolport. After acknowledgement, flight was immediately turned toward slurb which is IAF for the MLS runway 28 approach to the avon stolport. After approximately 2 mins ZDV called stating that we were 8 NM ese of patwo intersection, and off course. I explained that we were proceeding direct to slurb. We were then cleared for the approach and told to maintain 16300' or above until established on the 30 mi arc. As we approached patwo intersection and were descending, ZDV announced that radar contact was lost and that we should contact eagle approach. Being below FL180 and with VMC conditions and with VFR route authority, I cancelled IFR and the flight was completed VFR. Confusion is in the clearance: 'cleared for an approach.' this is the only approach to avon. There are 2 IAF's. If a certain IAF is to be used, it should be stated in the clearance. Otherwise, either approach fix is acceptable. Callback conversation with reporter revealed the following: confirmed that filed route was over patwo. Counseled that clearance for approach did not permit deviation from filed route, but only that flight could start descent at discretion as long as MEA not violated. Reporter stated that since they had requested direct they had misinterp clearance as also clearance direct to requested point. Was reviewed with controller and now understands requirement.

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Original NASA ASRS Text

Title: ACR MDT TRACK DEVIATION WHEN CLEARED FOR APCH ENROUTE.

Narrative: AT APPROX XA50, UPON HDOF FROM DEN DEP CTL TO ZDV, REQUEST WAS MADE FOR CLRNC DIRECT SLURB INTXN. CENTER REQUESTED THAT FLT TEMPORARILY CONTINUE AS FILED FOR TFC SEP. AT APPROX XB00 CLRNC WAS RECEIVED FOR AN APCH TO THE AVON STOLPORT. AFTER ACKNOWLEDGEMENT, FLT WAS IMMEDIATELY TURNED TOWARD SLURB WHICH IS IAF FOR THE MLS RWY 28 APCH TO THE AVON STOLPORT. AFTER APPROX 2 MINS ZDV CALLED STATING THAT WE WERE 8 NM ESE OF PATWO INTXN, AND OFF COURSE. I EXPLAINED THAT WE WERE PROCEEDING DIRECT TO SLURB. WE WERE THEN CLRED FOR THE APCH AND TOLD TO MAINTAIN 16300' OR ABOVE UNTIL ESTABLISHED ON THE 30 MI ARC. AS WE APCHED PATWO INTXN AND WERE DSNDING, ZDV ANNOUNCED THAT RADAR CONTACT WAS LOST AND THAT WE SHOULD CONTACT EAGLE APCH. BEING BELOW FL180 AND WITH VMC CONDITIONS AND WITH VFR ROUTE AUTHORITY, I CANCELLED IFR AND THE FLT WAS COMPLETED VFR. CONFUSION IS IN THE CLRNC: 'CLRED FOR AN APCH.' THIS IS THE ONLY APCH TO AVON. THERE ARE 2 IAF'S. IF A CERTAIN IAF IS TO BE USED, IT SHOULD BE STATED IN THE CLRNC. OTHERWISE, EITHER APCH FIX IS ACCEPTABLE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: CONFIRMED THAT FILED ROUTE WAS OVER PATWO. COUNSELED THAT CLRNC FOR APCH DID NOT PERMIT DEVIATION FROM FILED ROUTE, BUT ONLY THAT FLT COULD START DSCNT AT DISCRETION AS LONG AS MEA NOT VIOLATED. RPTR STATED THAT SINCE THEY HAD REQUESTED DIRECT THEY HAD MISINTERP CLRNC AS ALSO CLRNC DIRECT TO REQUESTED POINT. WAS REVIEWED WITH CTLR AND NOW UNDERSTANDS REQUIREMENT.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.